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1.  Gastro-enteritis outbreak among Nordic patients with psoriasis in a health centre in Gran Canaria, Spain: a cohort study 
Between November 2 and 10, 2002 several patients with psoriasis and personnel staying in the health centre in Gran Canaria, Spain fell ill with diarrhoea, vomiting or both. Patient original came from Norway, Sweden and Finland. The patient group was scheduled to stay until 8 November. A new group of patients were due to arrive from 7 November.
A retrospective cohort study was conducted to assess the extent of the outbreak, to identify the source and mode of transmission and to prevent similar problems in the following group.
Altogether 41% (48/116) of persons staying at the centre fell ill. Norovirus infection was suspected based on clinical presentations and the fact that no bacteria were identified. Kaplan criteria were met. Five persons in this outbreak were hospitalised and the mean duration of diarrhoea was 3 days. The consequences of the illness were more severe compared to many other norovirus outbreaks, possibly because many of the cases suffered from chronic diseases and were treated with drugs reported to affect the immunity (methotrexate or steroids).
During the two first days of the outbreak, the attack rate was higher in residents who had consumed dried fruit (adjusted RR = 3.1; 95% CI: 1.4–7.1) and strawberry jam (adjusted RR = 1.9; 95% CI: 0.9–4.1) than those who did not. In the following days, no association was found. The investigation suggests two modes of transmission: a common source for those who fell ill during the two first days of the outbreak and thereafter mainly person to person transmission. This is supported by a lower risk associated with the two food items at the end of the outbreak.
We believe that the food items were contaminated by foodhandlers who reported sick before the outbreak started. Control measures were successfully implemented; food buffets were banned, strict hygiene measures were implemented and sick personnel stayed at home >48 hours after last symptoms.
PMCID: PMC529448  PMID: 15511300
2.  Outbreak of SRSV gastroenteritis at an international conference traced to food handled by a post-symptomatic caterer. 
Epidemiology and Infection  1993;111(1):157-162.
In an outbreak of small round structured virus (SRSV) gastroenteritis at an international AIDS conference 67 people were ill with diarrhoea or vomiting, one requiring admission to hospital. Epidemiological investigations demonstrated that the vehicle of infection was food prepared by a foodhandler who was recovering from a mild gastrointestinal illness. The food most strongly associated with illness, coronation chicken, was prepared by the food handler on the second day after symptoms ceased. The investigation confirms the view that foodhandlers may contaminate food with SRSVs after cessation of symptoms and should remain off work until at least 48 h after recovery.
PMCID: PMC2271183  PMID: 8394241
3.  Hand Sanitiser Provision for Reducing Illness Absences in Primary School Children: A Cluster Randomised Trial 
PLoS Medicine  2014;11(8):e1001700.
In a cluster randomized trial, Patricia Priest and colleagues find that providing hand sanitizer along with hand hygiene education in primary school classrooms, compared with hand hygiene alone, does not reduce school absences.
Please see later in the article for the Editors' Summary
The potential for transmission of infectious diseases offered by the school environment are likely to be an important contributor to the rates of infectious disease experienced by children. This study aimed to test whether the addition of hand sanitiser in primary school classrooms compared with usual hand hygiene would reduce illness absences in primary school children in New Zealand.
Methods and Findings
This parallel-group cluster randomised trial took place in 68 primary schools, where schools were allocated using restricted randomisation (1∶1 ratio) to the intervention or control group. All children (aged 5 to 11 y) in attendance at participating schools received an in-class hand hygiene education session. Schools in the intervention group were provided with alcohol-based hand sanitiser dispensers in classrooms for the winter school terms (27 April to 25 September 2009). Control schools received only the hand hygiene education session. The primary outcome was the number of absence episodes due to any illness among 2,443 follow-up children whose caregivers were telephoned after each absence from school. Secondary outcomes measured among follow-up children were the number of absence episodes due to specific illness (respiratory or gastrointestinal), length of illness and illness absence episodes, and number of episodes where at least one other member of the household became ill subsequently (child or adult). We also examined whether provision of sanitiser was associated with experience of a skin reaction. The number of absences for any reason and the length of the absence episode were measured in all primary school children enrolled at the schools. Children, school administrative staff, and the school liaison research assistants were not blind to group allocation. Outcome assessors of follow-up children were blind to group allocation. Of the 1,301 and 1,142 follow-up children in the hand sanitiser and control groups, respectively, the rate of absence episodes due to illness per 100 child-days was similar (1.21 and 1.16, respectively, incidence rate ratio 1.06, 95% CI 0.94 to 1.18). The provision of an alcohol-based hand sanitiser dispenser in classrooms was not effective in reducing rates of absence episodes due to respiratory or gastrointestinal illness, the length of illness or illness absence episodes, or the rate of subsequent infection for other members of the household in these children. The percentage of children experiencing a skin reaction was similar (10.4% hand sanitiser versus 10.3% control, risk ratio 1.01, 95% CI 0.78 to 1.30). The rate or length of absence episodes for any reason measured for all children also did not differ between groups. Limitations of the study include that the study was conducted during an influenza pandemic, with associated public health messaging about hand hygiene, which may have increased hand hygiene among all children and thereby reduced any additional effectiveness of sanitiser provision. We did not quite achieve the planned sample size of 1,350 follow-up children per group, although we still obtained precise estimates of the intervention effects. Also, it is possible that follow-up children were healthier than non-participating eligible children, with therefore less to gain from improved hand hygiene. However, lack of effectiveness of hand sanitiser provision on the rate of absences among all children suggests that this may not be the explanation.
The provision of hand sanitiser in addition to usual hand hygiene in primary schools in New Zealand did not prevent disease of severity sufficient to cause school absence.
Trial registration
Australian New Zealand Clinical Trials Registry ACTRN12609000478213
Please see later in the article for the Editors' Summary
Editors' Summary
Throughout human history, infectious diseases have been major killers. In the 1300 s, for example, the black death killed a third of the European population. Other diseases such as smallpox and cholera have also devastated human populations. Now, though, a better understanding of the bacteria, viruses, and other microbes that cause infectious diseases and the availability of effective vaccines and antibiotics mean that, for the first time in human history, non-communicable (chronic) diseases such as heart attacks and strokes are killing and disabling more people around the world than infectious diseases. But this does not mean that we can be complacent about infectious diseases. The control of infectious diseases remains important, even in high-income countries, because of the contribution of infectious diseases to ill-health and because we need to manage the risk of epidemics and pandemics (disease outbreaks that affect a large proportion of the population of a country or the world, respectively) of influenza and other diseases.
Why Was This Study Done?
The control of infectious disease transmission in children is a particularly important component of disease control because children tend to have high rates of infectious disease and to have more physical contact with peers and with adults than other age groups, particularly in the school environment. It might be possible, therefore, to reduce the occurrence of many infectious respiratory and gastrointestinal diseases in communities by interrupting the transmission of infectious diseases between children at school, but how can this be achieved? In health care settings, good hand hygiene is a key component of infectious disease control, so, here, the researchers undertake a cluster randomized trial among primary school children in New Zealand to investigate whether the promotion of extra hand cleaning through the provision of alcohol-based hand sanitizer in classrooms can reduce illness absences among school children compared with normal hand hygiene (washing with soap and water, mainly in school bathrooms). A cluster randomized trial compares the outcomes of groups of participants (in this case, schools) chosen randomly to receive different interventions.
What Did the Researchers Do and Find?
The researchers randomly assigned 68 city primary schools to the intervention or control group. All the children (aged 5–11 years) attending the participating schools received a thirty-minute in-class hand hygiene education session. Alcohol-based hand sanitizer dispensers were installed in the classrooms of the intervention schools during the winter term, and the children were asked to use the dispensers after coughing or sneezing and on the way out of the classroom for morning break and lunch. The researchers report that the trial's primary outcome—the rate of absence episodes per 100 child-days due to any illness among “follow-up” children, individuals whose caregivers agreed to be asked about the reason for any absence—was similar in the intervention and control groups. Moreover, among the follow-up children, the provision of hand sanitizer did not reduce the number of absences due to a specific illness (respiratory or gastrointestinal), the length of illness and length of absence from school, or the number of episodes in which at least one other family member became ill. Finally, the number of absences for any reason, and length of absence episodes, in all the children enrolled at the participating schools did not differ between the intervention and control groups.
What Do These Findings Mean?
These findings suggest that the provision of hand sanitizer in addition to usual hand hygiene in primary schools in New Zealand did not prevent any infectious diseases severe enough to warrant school absence. Because the trial was undertaken during an influenza epidemic, influenza-related public health messages about good hand hygiene may have increased hand hygiene among all the children in the study and lessened the intervention's effectiveness. Other study limitations—including that only a third of caregivers agreed to be contacted about their child's absences, and these may have been caregivers who had already taught their children good hand hygiene—may also affect the accuracy of these findings and their generalizability to other high-income countries. However, these findings suggest that, in high-income countries where clean water for hand washing is readily available, putting resources into extra hand hygiene by providing hand sanitizer in classrooms may not be an effective way to break the child-to-child transmission of infectious diseases.
Additional Information
Please access these websites via the online version of this summary at
The US Centers for Disease Control and Prevention has information about hand-washing, when and how to wash your hands and use sanitizer, and hand-washing as a family activity; it also provides information about the importance of hand hygiene in health care settings
Public Health England provides information about hand-washing; its webpage about hand-washing in primary schools contains links to lesson plans about hand-washing for children aged 5–7 years and to e-Bug, a web-based student resource about infectious diseases and their prevention for children aged 7–14 years
Kidshealth, a US-based not-for-profit organization, also provides information about the importance of hand-washing for parents, kids, and teens (in English and Spanish)
PMCID: PMC4130492  PMID: 25117155
4.  A foodborne outbreak of Aeromonas hydrophila in a college, Xingyi City, Guizhou, China, 2012 
On 12 May 2012, over 200 college students with acute diarrhoea were reported to the Guizhou Center for Disease Control and Prevention. We conducted an investigation to identify the agent and mode of transmission and to recommend control measures.
A suspected case was a person at the college with onset of ≥ two of the following symptoms: diarrhoea (more than three loose stools in 24 hours), abdominal pain, vomiting or fever (> 37.5C) between 6 and 15 May 2012. A confirmed case also had a positive Aeromonas hydrophila culture from a stool sample. A retrospective-cohort study of 902 students compared attack rates (AR) by dining place, meals and food history. We reviewed the implicated premise, its processes and preparation of implicated food.
We identified 349 suspected cases (AR = 14%) and isolated Aeromonas hydrophila from three stools of 15 cases. Students who ate in cafeteria A were more likely to be ill compared to those eating in other places (relative risk [RR]: 3.1, 95% confidence interval [CI]: 2.0–4.8). The cohort study implicated cold cucumber (RR: 2.6, 95% CI: 2.0–3.3) and houttuynia dishes (RR: 1.8, 95% CI: 1.4–2.3). Environmental investigation showed that vegetables were washed in polluted water from a tank close to the sewage ditch, then left at 30 °C for two hours before serving. The Escherichia coli count of the tank was well above the standard for drinking-water.
This outbreak of Aeromonas hydrophila was most probably caused by salad ingredients washed in contaminated tank water. We recommended enhancing training of foodhandlers, ensuring tanks and sewerage systems comply with appropriate standards and adequate monitoring of drinking-water sources.
PMCID: PMC3729099  PMID: 23908938
5.  Food safety in hospital: knowledge, attitudes and practices of nursing staff of two hospitals in Sicily, Italy 
Food hygiene in hospital poses peculiar problems, particularly given the presence of patients who could be more vulnerable than healthy subjects to microbiological and nutritional risks. Moreover, in nosocomial outbreaks of infectious intestinal disease, the mortality risk has been proved to be significantly higher than the community outbreaks and highest for foodborne outbreaks. On the other hand, the common involvement in the role of food handlers of nurses or domestic staff, not specifically trained about food hygiene and HACCP, may represent a further cause of concern.
The purpose of this study was to evaluate knowledge, attitudes, and practices concerning food safety of the nursing staff of two hospitals in Palermo, Italy. Association with some demographic and work-related determinants was also investigated.
The survey was conducted, by using a semi-structured questionnaire, in March-November 2005 in an acute general hospital and a paediatric hospital, where nursing staff is routinely involved in food service functions.
Overall, 401 nurses (279, 37.1%, of the General Hospital and 122, 53.5%, of the Paediatric Hospital, respectively) answered. Among the respondents there was a generalized lack of knowledge about etiologic agents and food vehicles associated to foodborne diseases and proper temperatures of storage of hot and cold ready to eat foods. A general positive attitude towards temperature control and using clothing and gloves, when handling food, was shared by the respondents nurses, but questions about cross-contamination, refreezing and handling unwrapped food with cuts or abrasions on hands were frequently answered incorrectly. The practice section performed better, though sharing of utensils for raw and uncooked foods and thawing of frozen foods at room temperatures proved to be widely frequent among the respondents. Age, gender, educational level and length of service were inconsistently associated with the answer pattern.
More than 80% of the respondent nurses did not attend any educational course on food hygiene. Those who attended at least one training course fared significantly better about some knowledge issues, but no difference was detected in both the attitude and practice sections.
Results strongly emphasize the need for a safer management of catering in the hospitals, where non professional food handlers, like nursing or domestic staff, are involved in food service functions.
PMCID: PMC1852552  PMID: 17407582
6.  An Epidemiological Network Model for Disease Outbreak Detection 
PLoS Medicine  2007;4(6):e210.
Advanced disease-surveillance systems have been deployed worldwide to provide early detection of infectious disease outbreaks and bioterrorist attacks. New methods that improve the overall detection capabilities of these systems can have a broad practical impact. Furthermore, most current generation surveillance systems are vulnerable to dramatic and unpredictable shifts in the health-care data that they monitor. These shifts can occur during major public events, such as the Olympics, as a result of population surges and public closures. Shifts can also occur during epidemics and pandemics as a result of quarantines, the worried-well flooding emergency departments or, conversely, the public staying away from hospitals for fear of nosocomial infection. Most surveillance systems are not robust to such shifts in health-care utilization, either because they do not adjust baselines and alert-thresholds to new utilization levels, or because the utilization shifts themselves may trigger an alarm. As a result, public-health crises and major public events threaten to undermine health-surveillance systems at the very times they are needed most.
Methods and Findings
To address this challenge, we introduce a class of epidemiological network models that monitor the relationships among different health-care data streams instead of monitoring the data streams themselves. By extracting the extra information present in the relationships between the data streams, these models have the potential to improve the detection capabilities of a system. Furthermore, the models' relational nature has the potential to increase a system's robustness to unpredictable baseline shifts. We implemented these models and evaluated their effectiveness using historical emergency department data from five hospitals in a single metropolitan area, recorded over a period of 4.5 y by the Automated Epidemiological Geotemporal Integrated Surveillance real-time public health–surveillance system, developed by the Children's Hospital Informatics Program at the Harvard-MIT Division of Health Sciences and Technology on behalf of the Massachusetts Department of Public Health. We performed experiments with semi-synthetic outbreaks of different magnitudes and simulated baseline shifts of different types and magnitudes. The results show that the network models provide better detection of localized outbreaks, and greater robustness to unpredictable shifts than a reference time-series modeling approach.
The integrated network models of epidemiological data streams and their interrelationships have the potential to improve current surveillance efforts, providing better localized outbreak detection under normal circumstances, as well as more robust performance in the face of shifts in health-care utilization during epidemics and major public events.
Most surveillance systems are not robust to shifts in health care utilization. Ben Reis and colleagues developed network models that detected localized outbreaks better and were more robust to unpredictable shifts.
Editors' Summary
The main task of public-health officials is to promote health in communities around the world. To do this, they need to monitor human health continually, so that any outbreaks (epidemics) of infectious diseases (particularly global epidemics or pandemics) or any bioterrorist attacks can be detected and dealt with quickly. In recent years, advanced disease-surveillance systems have been introduced that analyze data on hospital visits, purchases of drugs, and the use of laboratory tests to look for tell-tale signs of disease outbreaks. These surveillance systems work by comparing current data on the use of health-care resources with historical data or by identifying sudden increases in the use of these resources. So, for example, more doctors asking for tests for salmonella than in the past might presage an outbreak of food poisoning, and a sudden rise in people buying over-the-counter flu remedies might indicate the start of an influenza pandemic.
Why Was This Study Done?
Existing disease-surveillance systems don't always detect disease outbreaks, particularly in situations where there are shifts in the baseline patterns of health-care use. For example, during an epidemic, people might stay away from hospitals because of the fear of becoming infected, whereas after a suspected bioterrorist attack with an infectious agent, hospitals might be flooded with “worried well” (healthy people who think they have been exposed to the agent). Baseline shifts like these might prevent the detection of increased illness caused by the epidemic or the bioterrorist attack. Localized population surges associated with major public events (for example, the Olympics) are also likely to reduce the ability of existing surveillance systems to detect infectious disease outbreaks. In this study, the researchers developed a new class of surveillance systems called “epidemiological network models.” These systems aim to improve the detection of disease outbreaks by monitoring fluctuations in the relationships between information detailing the use of various health-care resources over time (data streams).
What Did the Researchers Do and Find?
The researchers used data collected over a 3-y period from five Boston hospitals on visits for respiratory (breathing) problems and for gastrointestinal (stomach and gut) problems, and on total visits (15 data streams in total), to construct a network model that included all the possible pair-wise comparisons between the data streams. They tested this model by comparing its ability to detect simulated disease outbreaks implanted into data collected over an additional year with that of a reference model based on individual data streams. The network approach, they report, was better at detecting localized outbreaks of respiratory and gastrointestinal disease than the reference approach. To investigate how well the network model dealt with baseline shifts in the use of health-care resources, the researchers then added in a large population surge. The detection performance of the reference model decreased in this test, but the performance of the complete network model and of models that included relationships between only some of the data streams remained stable. Finally, the researchers tested what would happen in a situation where there were large numbers of “worried well.” Again, the network models detected disease outbreaks consistently better than the reference model.
What Do These Findings Mean?
These findings suggest that epidemiological network systems that monitor the relationships between health-care resource-utilization data streams might detect disease outbreaks better than current systems under normal conditions and might be less affected by unpredictable shifts in the baseline data. However, because the tests of the new class of surveillance system reported here used simulated infectious disease outbreaks and baseline shifts, the network models may behave differently in real-life situations or if built using data from other hospitals. Nevertheless, these findings strongly suggest that public-health officials, provided they have sufficient computer power at their disposal, might improve their ability to detect disease outbreaks by using epidemiological network systems alongside their current disease-surveillance systems.
Additional Information.
Please access these Web sites via the online version of this summary at
Wikipedia pages on public health (note that Wikipedia is a free online encyclopedia that anyone can edit, and is available in several languages)
A brief description from the World Health Organization of public-health surveillance (in English, French, Spanish, Russian, Arabic, and Chinese)
A detailed report from the US Centers for Disease Control and Prevention called “Framework for Evaluating Public Health Surveillance Systems for the Early Detection of Outbreaks”
The International Society for Disease Surveillance Web site
PMCID: PMC1896205  PMID: 17593895
7.  Food-borne outbreak of group G streptococcal sore throat in an Israeli military base. 
Epidemiology and Infection  1987;99(2):249-255.
A food-borne outbreak of sore throat caused by Lancefield group G beta-haemolytic streptococci and involving 50 persons occurred in May 1983 in an Israeli military camp. All of the patients available for clinical examination had sore throat and difficulty in swallowing. Exudative tonsillitis occurred in 46% of the patients and the body temperature was above 37.5 degrees C in 81%. The pattern of attack was uniform over the base and 37 became ill during the night and morning of the 5 May. Thirty-two (84%) of the throat cultures taken from 37 patients grew group G beta-haemolytic streptococci. Eight of 29 contacts were positive for group G beta-haemolytic streptococci and 6 of the 28 foodhandlers examined had positive cultures of the same group. The organism was also isolated from one food sample. The epidemiological and laboratory investigations indicated that a food handler, a convalescent carrier of group G streptococci, might have been the source of infection. Assumptions on the potential of non-group A streptococci to cause epidemics are discussed.
PMCID: PMC2249277  PMID: 3678389
8.  Identification of a carrier by using Vi enzyme-linked immunosorbent assay serology in an outbreak of typhoid fever on an Indian reservation. 
Journal of Clinical Microbiology  1983;18(6):1320-1322.
In May 1981 an outbreak of typhoid fever occurred in a small village on a southwestern United States Indian reservation. Five of the six culture-proven cases, but only 2 of 15 community, age-matched controls, had eaten food prepared for a party held in the village on 20 April (chi-square = 4.3; P less than 0.05). Food histories obtained from 16 persons who ate food at the party suggested that chicken with chili (P = 0.03) and potato salad (P = 0.09) were possible vehicles. Eleven adults who attended the party, 5 of whom helped prepare an implicated food, were studied with one or more stool cultures and serum for Vi antibody by using enzyme-linked immunosorbent assay (ELISA) and hemagglutination techniques. All initial stool cultures were negative for Salmonella typhi; however, one subject, a 70-year-old female foodhandler, had a Vi antibody titer of 1:320 by ELISA. Subsequent cultures from this subject were positive for S. typhi. ELISA for Vi antibody directed the investigators to a single individual as the most probable carrier source and obviated the need for multiple fecal cultures from the other potential carriers identified by the epidemiological investigation.
PMCID: PMC272900  PMID: 6655039
9.  The Effect of Handwashing at Recommended Times with Water Alone and With Soap on Child Diarrhea in Rural Bangladesh: An Observational Study 
PLoS Medicine  2011;8(6):e1001052.
By observing handwashing behavior in 347 households from 50 villages across rural Bangladesh in 2007, Stephen Luby and colleagues found that hand washing with soap or hand rinsing without soap before food preparation can both reduce the burden of childhood diarrhea.
Standard public health interventions to improve hand hygiene in communities with high levels of child mortality encourage community residents to wash their hands with soap at five separate key times, a recommendation that would require mothers living in impoverished households to typically wash hands with soap more than ten times per day. We analyzed data from households that received no intervention in a large prospective project evaluation to assess the relationship between observed handwashing behavior and subsequent diarrhea.
Methods and Findings
Fieldworkers conducted a 5-hour structured observation and a cross-sectional survey in 347 households from 50 villages across rural Bangladesh in 2007. For the subsequent 2 years, a trained community resident visited each of the enrolled households every month and collected information on the occurrence of diarrhea in the preceding 48 hours among household residents under the age of 5 years. Compared with children living in households where persons prepared food without washing their hands, children living in households where the food preparer washed at least one hand with water only (odds ratio [OR] = 0.78; 95% confidence interval [CI] = 0.57–1.05), washed both hands with water only (OR = 0.67; 95% CI = 0.51–0.89), or washed at least one hand with soap (OR = 0.30; 95% CI = 0.19–0.47) had less diarrhea. In households where residents washed at least one hand with soap after defecation, children had less diarrhea (OR = 0.45; 95% CI = 0.26–0.77). There was no significant association between handwashing with or without soap before feeding a child, before eating, or after cleaning a child's anus who defecated and subsequent child diarrhea.
These observations suggest that handwashing before preparing food is a particularly important opportunity to prevent childhood diarrhea, and that handwashing with water alone can significantly reduce childhood diarrhea.
Please see later in the article for the Editors' Summary
Editors' Summary
The resurgence of donor interest in regarding water and sanitation as fundamental public health issues has been a welcome step forward and will do much to improve the health of the 1.1 billion people world-wide without access to clean water and the 2.4 billion without access to improved sanitation. However, improving hygiene practices is also very important—studies have consistently shown that handwashing with soap reduces childhood diarrheal disease—but in reality is particularly difficult to do as this activity involves complex behavioral changes. Therefore although public health programs in communities with high child mortality commonly promote handwashing with soap, this practice is still uncommon and washing hands with water only is still common practice—partly because of the high cost of soap relative to income, the risk that conveniently placed soap would be stolen or wasted, and the inconvenience of fetching soap.
Handwashing promotion programs often focus on five “key times” for handwashing with soap—after defecation, after handling child feces or cleaning a child's anus, before preparing food, before feeding a child, and before eating—which would require requesting busy impoverished mothers to wash their hands with soap more than ten times a day.
Why Was This Study Done?
In addition to encouraging handwashing only at the most critical times, clarifying whether handwashing with water alone, a behavior that is seemingly much easier for people to practice, but for which there is little evidence, may be a way forward. In order to guide more focused and evidence-based recommendations, the researchers evaluated the control group of a large handwashing, hygiene/sanitation, and water quality improvement program—Sanitation, Hygiene Education and Water supply-Bangladesh (SHEWA-B), organized and supported by the Bangladesh Government, UNICEF, and the UK's Department for International Development. The researchers analyzed the relationship between handwashing behavior as observed at baseline and the subsequent experience of child diarrhea in participating households to identify which specific handwashing behaviors were associated with less diarrhea in young children.
What Did the Researchers Do and Find?
The SHEWA-B intervention targeted 19.6 million people in rural Bangladesh in 68 subdistricts. In this study and with community and household consent, the researchers organized trained field workers, using a pretested instrument, to note handwashing behavior at key times and recorded handwashing behavior of all observed household at baseline in 50 randomly selected villages that served as nonintervention control households to compare with outcomes to communities receiving the SHEWA-B program. The fieldworkers recruited community monitors, female village residents who completed 3 days training on how to administer the monthly diarrhea survey, to record the frequency of diarrhea in children aged less than 3 years in control households for the subsequent two years. The researchers used statistical models to evaluate the association between the exposure variables (household characteristics and observed handwashing) and diarrhea.
Using these methods, the researchers found that compared to no handwashing at all before food preparation, children living in households where the food preparer washed at least one hand with water only, washed both hands with water only, or washed at least one hand with soap, had less diarrhea with odds ratios (ORs) of 0.78, 0.67, and 0.19, respectively. In households where residents washed at least one hand with soap after defecation, children had less diarrhea (OR = 0.45), but there was no significant association between handwashing with or without soap before feeding a child, before eating, or after cleaning a child's anus, and subsequent child diarrhea.
What Do These Findings Mean?
These findings from 50 villages across rural Bangladesh where fecal environmental contamination, undernutrition, and diarrhea are common, suggest that handwashing before preparing food is a particularly important opportunity to prevent childhood diarrhea, and also that handwashing with water alone can significantly reduce childhood diarrhea. In contrast to current standard recommendations, these results suggest that promoting handwashing exclusively with soap may be unwarranted. Handwashing with water alone might be seen as a step on the handwashing ladder: handwashing with water is good; handwashing with soap is better. Therefore, handwashing promotion programs in rural Bangladesh should not attempt to modify handwashing behavior at all five key times, but rather, should focus primarily on handwashing after defecation and before food preparation. Furthermore, research to develop and evaluate handwashing messages that account for the limited time and soap supplies available for low-income families, and are focused on those behaviors where there is the strongest evidence for a health benefit could help identify more effective strategies.
Additional Information
Please access these Web sites via the online version of this summary at
A four-part collection of Policy Forum articles published in November 2010 in PLoS Medicine, called “Water and Sanitation,” provides information on water, sanitation, and hygiene
Hygiene Central provides information on improving hygiene practices
PMCID: PMC3125291  PMID: 21738452
10.  Epidemiology of Foodborne Norovirus Outbreak in Incheon, Korea 
Journal of Korean Medical Science  2010;25(8):1128-1133.
On June 14, 2008, an outbreak of gastroenteritis occurred among elementary school students in Incheon. We conducted an investigation to identify the source and described the extent of the outbreak. We performed a retrospective cohort study among students, teachers and food handlers exposed to canteen food in the elementary school. Using self-administered questionnaires we collected information on symptoms, days of canteen food eaten, food items consumed. Stool samples were collected from 131 symptomatic people and 11 food handlers. The catering kitchen was inspected and food samples were taken. Of the 1,560 people who ate canteen food, 117 were symptomatic cases, and the attack rate was 7.5%. Consumption of cucumber-crown daisy salad (RR=2.71), fresh cabbage mix (RR=2.23), dried radish salad (RR=3.04) and young radish kimchi (RR=2.52) were associated with illness. Sixty-four (45%) of the 142 stool specimens were positive for Norovirus. Norovirus was detected in 2 food handlers. Interviews with kitchen staff indicated the likelihood of contamination from an infected food handler to the dried radish salad during food processing. The excretion of Norovirus from asymptomatic food handlers may be an infection source of Norovirus outbreaks.
PMCID: PMC2908779  PMID: 20676321
Disease Outbreaks; Norovirus
11.  Food safety and foodborne disease in 21st century homes 
Over the past decade there has been a growing recognition of the involvement of the home in several public health and hygiene issues. Perhaps the best understood of these issues is the role of the home in the transmission and acquisition of foodborne disease. The incidence of foodborne disease is increasing globally. Although foodborne disease data collection systems often miss the mass of home-based outbreaks of sporadic infection, it is now accepted that many cases of foodborne illness occur as a result of improper food handling and preparation by consumers in their own kitchens. Some of the most compelling evidence has come from the international data on Salmonella species and Campylobacter species infections.
By its very nature, the home is a multifunctional setting and this directly impacts upon the need for better food safety in the home. In particular, the growing population of elderly and other immnocompromised individuals living at home who are likely to be more vulnerable to the impact of foodborne disease is an important aspect to consider. In addition, some developed nations are currently undergoing a dramatic shift in healthcare delivery, resulting in millions of patients nursed at home. Other aspects of the home that are unique in terms of food safety are the use of the home as a daycare centre for preschool age children, the presence of domestic animals in the home and the use of the domestic kitchen for small-scale commercial catering operations. At the global level, domestic food safety issues for the 21st century include the continued globalization of the food supply, the impact of international travel and tourism, and the impact of foodborne disease on developing nations.
A number of countries have launched national campaigns to reduce the burden of foodborne disease, including alerting consumers to the need to practice food safety at home. Home hygiene practice and consumer hygiene products are being refined and targeted to areas of risk, including preventing the onward transmission of foodborne illness via the inanimate environment. It has been said that food safety in the home is the last line of defense against foodborne disease, and it is likely that this will remain true for the global population in the foreseeable future.
PMCID: PMC2094945  PMID: 18159469
Food safety; Foodborne disease; Home
12.  A review of interventions triggered by hepatitis A infected food-handlers in Canada 
In countries with low hepatitis A (HA) endemicity, infected food handlers are the source of most reported foodborne outbreaks. In Canada, accessible data repositories of infected food handler incidents are not available. We undertook a systematic review of such incidents to evaluate the extent of viral transmission through food contamination and the scope of post-exposure prophylaxis (PEP) interventions.
A systematic search of MEDLINE and EMBASE was conducted to identify published reports of incidents in Canada. An expanded search of a news repository (i.e., transcripts from newspapers and newscasts) was also conducted to identify the location and timing of an incident, which was used to retrieve the related report by contacting local public health departments. Data pertaining to case identification, public health risk, PEP interventions, and associated costs was independently abstracted by two reviewers and summarized according to incidents with and without large PEP interventions.
A total of 16 incidents were identified from 1998–2004. There were approximately 3 incidents requiring public notification per year. Only 12.5% of incidents were described in published reports, indicating that published data significantly underestimated the number of incidents and PEP interventions. Data pertaining to the remaining incidents was unpublished, sparse and highly dispersed at the local public health level.
Six of the 16 incidents required large PEP interventions to immunize on average 5000 potentially exposed individuals. Secondary transmission was low. Characteristics of incidents requiring large PEP interventions included potentially infectious food handlers working with uncooked food for a prolonged duration in high-volume grocery stores in high-density urban areas.
Infected food handlers with hepatitis A virus (HAV) requiring public notification are not infrequent in Canada. Published data severely underestimated the burden of PEP intervention. Better and consistent reporting at the local and national level as well as a national data repository should be considered for the management of future incidents.
PMCID: PMC1702355  PMID: 17156461
13.  Year-Round Prevalence of Norovirus in the Environment of Catering Companies without a Recently Reported Outbreak of Gastroenteritis▿ 
Food handlers play an important role in the transmission of norovirus (NoV) in food-borne outbreaks of gastroenteritis (GE). In a year-round prevalence study, the prevalence of NoV in catering companies without recently reported outbreaks of GE was investigated and compared to the observed prevalence in catering companies with recently reported outbreaks. Swab samples were collected from surfaces in the kitchens and (staff) bathrooms in 832 randomly chosen companies and analyzed for the presence of NoV RNA. In total, 42 (1.7%) out of 2,496 environmental swabs from 35 (4.2%) catering companies tested positive. In contrast, NoV was detected in 147 (39.7%) of the 370 samples for 44 (61.1%) of the 72 establishments associated with outbreaks of gastroenteritis. NoV-positive swabs were more frequently found in winter, in specific types of companies (elderly homes and lunchrooms), and in establishments with separate bathrooms for staff. We found a borderline association with population density but no relation to the number of employees. Sequence analysis showed that environmental strains were interspersed with strains found in outbreaks of illness in humans. Thus, the presence of NoV in catering companies seemed to mirror the presence in the population but was strongly increased when associated with food-borne GE. Swabs may therefore serve as a valuable tool in outbreak investigations for the identification of the causative agent, although results should be interpreted with care, taking into account all other epidemiological data.
PMCID: PMC3126400  PMID: 21378056
14.  Outbreak of Infection with Hepatitis A Virus (HAV) Associated with a Foodhandler and Confirmed by Sequence Analysis Reveals a New HAV Genotype IB Variant 
Journal of Clinical Microbiology  2004;42(6):2825-2828.
An outbreak of infection with hepatitis A virus associated with a foodhandler and involving 26 subjects occurred in Southern Italy. Sequence analysis of the VP3-VP1 and VP1-P2A junctions confirmed that the outbreak was due to a point source and allowed the identification of a new genotype IB variant. This report confirms the usefulness of sequence-based molecular fingerprinting during outbreaks.
PMCID: PMC427829  PMID: 15184483
15.  Profile of catering staff at a tertiary care hospital in Mumbai 
The Australasian Medical Journal  2011;4(3):148-154.
Food borne illnesses, even today, continue to be a major public health problem in both developing and developed nations. Food handlers play an important role in ensuring food safety throughout the chain of production, processing, storage and preparation.Health of food handlers is of great importance for maintaining hygienic quality of food prepared and served by them. Thus, the present study was conducted to study socio-demographic characteristics, morbidity pattern and immunization status of catering staff at a tertiary care hospital in Mumbai
A cross sectional study was conducted from August 2010 to November 2010. Out of the total of 162 food handlers working in 11 food service establishments, 137 were interviewed face to face using a semi-structured questionnaire, while remaining 25 food handlers were excluded because of either their absence or not giving consent. The food handlers were assessed clinically for personal hygiene and investigated for hemoglobin, stool routine and sputum AFB examination.
82 (59.8%) food handlers were from the age group 10 - 29 years, 113 (82.5%) male, 95 (69%) married, 59 (43.1%) educated up to primary level. Only 7 (5.1%) had ever received a dose of typhoid vaccine. 103 (75.2%) had an addiction, majority consuming gutkha 59 (57.3%). Dental caries 32 (23.4%) was the most common morbidity identified. Entamoeba histolytica was isolated in 13 (9.5%) subjects.
This study has confirmed an association between educational status and personal hygiene suggesting the need for greater personal hygiene in this group. Preemployment and periodical medical examination should be encouraged.
PMCID: PMC3562963  PMID: 23390464
Food handler; personal hygiene; dental caries; periodic medical examination
16.  An outbreak of cyclosporiasis in 1996 associated with consumption of fresh berries- Ontario 
A large foodborne outbreak of cyclosporiasis occurred in North America in 1996. An index cluster of cases associated with a catered event on May 11, 1996, in Ontario sparked the recognition of this outbreak in Canada.
To describe the Ontario experience with the North American outbreak of cyclosporiasis in 1996.
Public health units investigated the index and subsequent event-associated clusters. Investigations included retrospective cohort studies of clusters, traceback of suspect foods and a case-control study of sporadic cases. These activities, coordinated with those in the United States, were part of an international investigation.
In Ontario, 232 cases of cyclosporiasis (20 laboratory-confirmed and 72 clinically defined cases associated with seven events plus 140 additional laboratory-confirmed sporadic cases) were identified between May 1 and July 30, 1996. For the index cluster, a strawberry flan with raspberries and blueberries was the only significant exposure (relative risk 2.16, P=0.02). Fresh berries were served at all seven events associated with clusters of cases. Raspberries were definitely served at three events, possibly served at three events, and not served at one event. Only imported berries were available in Ontario in May 1996, when initial clusters and sporadic cases were identified. The raspberries served at the two events with well documented traceback data came from Guatemala. Univariate analyses of the matched case-control study demonstrated that illness was associated with consumption of raspberries (matched odds ratio 21.0, 95% CI 3.48 to 448) and strawberries (matched odds ratio 28.5, 95% CI 4.02 to 478). Further evidence amassed by the international investigation compellingly implicated Guatemalan raspberries as the vehicle of the outbreak.
Cyclosporiasis may be acquired domestically from the consumption of contaminated produce. The scope and vehicle of this international foodborne outbreak were recognized through a coordinated public health response.
PMCID: PMC2094747  PMID: 18159270
Canada; Cyclosporiasis; Cyclospora cayetanensis; Foodborne outbreak
17.  Hepatitis A vaccine should receive priority in National Immunization Schedule in India 
Human Vaccines & Immunotherapeutics  2012;8(8):1132-1134.
Hepatitis A is an acute, usually self-limiting infection of the liver caused by a virus known as hepatitis A virus (HAV). Humans are the only reservoir of the virus; transmission occurs primarily through the fecal-oral route and is closely associated with poor sanitary conditions. The virus has a worldwide distribution and causes about 1.5 million cases of clinical hepatitis each year. The risk of developing symptomatic illness following HAV infection is directly correlated with age. As many 85% of children below 2 y and 50% of those between 2–5 y infected with HAV are anicteric, and among older children and adults, infection usually causes clinical disease, with jaundice occurring in more than 70% of cases. The infection is usually self-limiting with occasional fulminant hepatic failure and mortality. In most developing countries in Asia and Africa, hepatitis A is highly endemic such that a large proportion of the population acquires immunity through asymptomatic infection early in life. HAV is endemic in India; most of the population is infected asymptomatically in early childhood with life-long immunity. Several outbreaks of hepatitis A in various parts of India have been recorded in the past decade such that anti-HAV positivity varied from 26 to 85%. Almost 50% of children of ages 1–5 y were found to be susceptible to HAV. Any one of the licensed vaccines may be used since all have nearly similar efficacy and safety profiles (except for post-exposure prophylaxis / immunocompromised patients, where only inactivated vaccines may be used). Two doses 6 mo apart are recommended for all vaccines. All Hepatitis A vaccines are licensed for use in children aged 1 y or older. However in the Indian scenario, it is preferable to administer the vaccines at age 18 mo or more when maternal antibodies have completely declined. Vaccination at this age is preferable to later since it is easier to integrate with the existing schedule, protects those who have no antibodies, and protects children by the time they attend day care. In India the vaccine against hepatitis A is available for the people who can afford it, but the government of India should give this vaccine as a priority in the national immunization schedule.
PMCID: PMC3551887  PMID: 22854671
hepatitis A virus; immunity; jaundice; outbreak; vaccines
18.  An outbreak of Bacillus cereus food poisoning--are caterers supervised sufficiently. 
Public Health Reports  1992;107(4):477-480.
Bacillus cereus is an uncommonly reported cause of foodborne illness in the United States. In May 1989, an outbreak of B. cereus gastroenteritis occurred among 140 guests who had attended a catered wedding reception in Napa, CA. Investigation established Cornish game hens served at the event as the vehicle for disease transmission (OR = 29, P = 0.0001). Although the spores of B. cereus are ubiquitous, large numbers of toxin-producing organisms (more than 10(5) per gram of food) are required for illness to occur. In the Napa outbreak, bacterial multiplication was facilitated at several points during the preparation and transportation of the food. While a licensed restaurant kitchen was used, the facilities were clearly inadequate for the event. At present, the California Health and Safety Code does not address the scope of catering operations. As caterers increase in number, there will be a growing need for governmental oversight to ensure that food production on a large scale is conducted safely.
PMCID: PMC1403681  PMID: 1641447
19.  Epidemiology of Campylobacter jejuni Outbreak in a Middle School in Incheon, Korea 
Journal of Korean Medical Science  2010;25(11):1595-1600.
On July 6, 2009, an outbreak of gastroenteritis occurred among middle school students in Incheon. An investigation to identify the source and describe the extent of the outbreak was conducted. A retrospective cohort study among students, teachers, and food handlers exposed to canteen food in the middle school was performed. Using self-administered questionnaires, information was collected concerning on symptoms, days that canteen food was consumed, and food items consumed. Stool samples were collected from 66 patients and 11 food handlers. The catering kitchen was inspected and food samples were taken. Of the 791 people who ate canteen food, 92 cases became ill, representing an attack rate of 11.6%. Thirty-one (40.3%) of the 77 stool specimens were positive for Campylobacter jejuni. Interviews with kitchen staff indicated the likelihood that undercooked chicken was provided. This is the first recognized major C. jejuni outbreak associated with contaminated chicken documented in Korea.
PMCID: PMC2966996  PMID: 21060748
Campylobacter; Epidemiology; Disease Outbreaks
20.  Lessons from Norovirus Outbreak in Warsaw, Poland, December 2012 
Food and Environmental Virology  2014;6(4):276-281.
Efficient foodborne outbreak investigations are important for identification of gaps in food safety and public health practice. This article reports on an investigation of a gastroenteritis outbreak linked to catering food following a Christmas reception at the National Institute of Public Health-National Institute of Hygiene (NIPH-NIH) in Warsaw in December 2012. Of 192 employees eating food at the catering event, 97 (50.5 %) developed symptoms. Persons eating dishes with recipes containing frozen carrots were five times more likely to develop gastrointestinal symptoms compared to those who did not eat carrots. Laboratory analysis identified norovirus in stool samples taken from symptomatic persons. Leftover food was not available for testing. The investigators did not collect stool specimens from food handlers and did not conduct trace backs for the suspected food ingredients. This investigation underlines the need for a revision of an existing procedures and importance of their complementation with detailed instructions for the local public health authorities for effective completion of foodborne outbreaks investigations in Poland.
PMCID: PMC4228110  PMID: 25326199
Outbreak investigation; Foodborne; Viral disease; Norovirus; Poland
21.  Multidisciplinary Prospective Study of Mother-to-Child Chikungunya Virus Infections on the Island of La Réunion 
PLoS Medicine  2008;5(3):e60.
An outbreak of chikungunya virus affected over one-third of the population of La Réunion Island between March 2005 and December 2006. In June 2005, we identified the first case of mother-to-child chikungunya virus transmission at the Groupe Hospitalier Sud-Réunion level-3 maternity department. The goal of this prospective study was to characterize the epidemiological, clinical, biological, and radiological features and outcomes of all the cases of vertically transmitted chikungunya infections recorded at our institution during this outbreak.
Methods and Findings
Over 22 mo, 7,504 women delivered 7,629 viable neonates; 678 (9.0%) of these parturient women were infected (positive RT-PCR or IgM serology) during antepartum, and 61 (0.8%) in pre- or intrapartum. With the exception of three early fetal deaths, vertical transmission was exclusively observed in near-term deliveries (median duration of gestation: 38 wk, range 35–40 wk) in the context of intrapartum viremia (19 cases of vertical transmission out of 39 women with intrapartum viremia, prevalence rate 0.25%, vertical transmission rate 48.7%). Cesarean section had no protective effect on transmission. All infected neonates were asymptomatic at birth, and median onset of neonatal disease was 4 d (range 3–7 d). Pain, prostration, and fever were present in 100% of cases and thrombocytopenia in 89%. Severe illness was observed in ten cases (52.6%) and mainly consisted of encephalopathy (n = 9; 90%). These nine children had pathologic MRI findings (brain swelling, n = 9; cerebral hemorrhages, n = 2), and four evolved towards persistent disabilities.
Mother-to-child chikungunya virus transmission is frequent in the context of intrapartum maternal viremia, and often leads to severe neonatal infection. Chikungunya represents a substantial risk for neonates born to viremic parturients that should be taken into account by clinicians and public health authorities in the event of a chikungunya outbreak.
In a prospective study on the island of La Réunion, Marc Lecuit and colleagues find frequent transmission of Chikungunya virus by viremic mothers giving birth during an outbreak, resulting in serious infant illness.
Editors' Summary
Chikungunya virus, an emerging infectious agent that is transmitted by day-biting mosquitoes, was first isolated from a patient in Tanzania in the early 1950s. Since then, major outbreaks of chikungunya fever have occurred throughout sub-Saharan Africa and in Southeast Asia, India, and the Western Pacific, usually at intervals of about 7–8 years. The virus causes fever, rash, severe joint and muscle pains, and sometimes arthritis (joint inflammation). These symptoms develop within 3–7 days of being bitten by an infected mosquito. Most people recover fully within a few weeks, but joint pain can sometimes continue for years. There is no treatment for chikungunya fever, but the symptoms can be eased with anti-inflammatory drugs. Preventative measures include covering arms and legs and using insecticides to avoid insect bites and depriving the mosquitoes of their breeding sites by draining standing water from man-made containers near human dwellings.
Why Was This Study Done?
In 2005, chikungunya fever appeared for the first time on several islands in the Indian Ocean. On La Réunion Island, the disease affected 300,000 people—more than one-third of the population—between March 2005 and December 2006. In June 2005, clinicians identified the first case of mother-to-child chikungunya virus transmission (vertical transmission). Public-health officials and clinicians need to know more about how often vertical transmission occurs and its clinical implications to help them prepare for future chikungunya fever outbreaks. In this study, the researchers identify and characterize all the cases of vertical chikungunya virus transmission that occurred at the largest hospital on La Réunion Island during the 2005–6 outbreak.
What Did the Researchers Do and Find?
The researchers enrolled all 7,504 women who gave birth at the hospital during the outbreak and their 7,629 children into their study. They then used “RT-PCR” (which detects the genome of virus particles during an active infection) and “IgM serology” (which looks for an immune response to recent infection) to determine which women had been infected with chikungunya virus during their pregnancy. 678 of the new mothers had been infected sometime between conception and a week before delivery, 22 mothers had been infected between 7 and 3 days before delivery, and 39 had been infected 2 days either side of delivery (the “intrapartum” period). Except for three early fetal deaths that were associated with chikungunya virus infections, vertical transmission was seen only in babies born to mothers infected with the virus intrapartum. 19 of the babies born to these women were infected with the virus—a vertical transmission rate of nearly 50%. The women who transmitted the virus to their offspring had more virus in their placenta than those who did not transmit the infection. Delivery by emergency cesarean section did not prevent transmission. All the infected babies were born healthy but developed fever, weakness, and pain within 3–7 days. In many of them, the number of platelets (clot-forming particles) in their blood also dropped dramatically. Ten babies became seriously ill—nine of them developed brain swelling; two had bleeding into their brain. Four children had lasting disabilities at the end of the study.
What Do These Findings Mean?
These findings show that mother-to-child transmission of chikungunya virus occurs frequently when women are infected with the virus at the time of delivery and that newborn children infected by this route can become very ill. Although these results do not find that cesarean section reduces infection rates, 90% of cesarean sections involving infected infants were performed urgently, rather than planned. The study also provides no information about whether delaying delivery, provided that no fetal distress is observed, until the mother's viral load has decreased might be beneficial. More studies are needed to provide a complete description of both the short-term and long-term effects of chikungunya virus infection in newborn babies, but it is clear that clinicians should monitor babies exposed to chikungunya virus during delivery for a week after their birth. Most importantly, clinicians and public-health officials will need to take account of the threat that the chikungunya virus poses to newborn children whenever and wherever it emerges.
Additional Information.
Please access these Web sites via the online version of this summary at
Read the related PLoS Medicine 10.1371/journal.pmed.0050068
The World Health Organization provides information about chikungunya fever and a brief description of the recent chikungunya outbreak in the Indian Ocean (in English, French, Spanish, Arabic, Chinese, and Russian)
The US Centers for Disease Control and Prevention has a fact sheet on chikungunya fever
The UK Health Protection Agency also provides information about chikungunya virus, including news on recent outbreaks
The French Institut de Veille Sanitaire (Institute for Public Health Surveillance) has a Web page on chikungunya (in French)
The Institut Pasteur has a Web page on chikungunya research (in French and English)
PMCID: PMC2267812  PMID: 18351797
22.  Food-borne norovirus-outbreak at a military base, Germany, 2009 
Norovirus is often transmitted from person-to-person. Transmission may also be food-borne, but only few norovirus outbreak investigations have identified food items as likely vehicles of norovirus transmission through an analytical epidemiological study.
During 7-9 January, 2009, 36 persons at a military base in Germany fell ill with acute gastroenteritis. Food from the military base's canteen was suspected as vehicle of infection, norovirus as the pathogen causing the illnesses. An investigation was initiated to describe the outbreak's extent, to verify the pathogen, and to identify modes of transmission and source of infection to prevent further cases.
For descriptive analysis, ill persons were defined as members of the military base with acute onset of diarrhoea or vomiting between 24 December 2008, and 3 February 2009, without detection of a pathogen other than norovirus in stools. We conducted a retrospective cohort study within the headquarters company. Cases were military base members with onset of diarrhoea or vomiting during 5-9 January. We collected information on demographics, food items eaten at the canteen and contact to ill persons or vomit, using a self-administered questionnaire. We compared attack rates (AR) in exposed and unexposed persons, using bivariable and multivariable logistic regression modelling. Stool specimens of ill persons and canteen employees, canteen food served during 5-7 January and environmental swabs were investigated by laboratory analysis.
Overall, 101/815 (AR 12.4%) persons fell ill between 24 December 2008 and 3 February 2009. None were canteen employees. Most persons (n = 49) had disease onset during 7-9 January. Ill persons were a median of 22 years old, 92.9% were male. The response for the cohort study was 178/274 (72.1%). Of 27 cases (AR 15.2%), 25 had eaten at the canteen and 21 had consumed salad. Salad consumption on 6 January (aOR: 8.1; 95%CI: 1.5-45.4) and 7 January (aOR: 15.7; 95%CI: 2.2-74.1) were independently associated with increased risk of disease.
Norovirus was detected in 8/28 ill persons' and 4/25 canteen employees' stools, 6/55 environmental swabs and 0/33 food items. Sequences were identical in environmental and stool samples (subtype II.4 2006b), except for those of canteen employees. Control measures comprised cohort isolation of symptomatic persons, exclusion of norovirus-positive canteen employees from work and disinfection of the canteen's kitchen.
Our investigation indicated that consumption of norovirus-contaminated salad caused the peak of the outbreak on 7-9 January. Strict personal hygiene and proper disinfection of environmental surfaces remain crucial to prevent norovirus transmission.
PMCID: PMC2831023  PMID: 20163705
23.  An outbreak of acute norovirus gastroenteritis in a boarding school in Shanghai: a retrospective cohort study 
BMC Public Health  2014;14(1):1092.
More than 200 students and teachers at a boarding school in Shanghai developed acute gastroenteritis in December, 2012. The transmission mode remained largely unknown. An immediate epidemiological investigation was conducted to identify it.
Using a retrospective cohort design, we investigated demographic characteristics, school environment, and previous contacts with people who had diarrhea and/or vomiting, drinking water conditions, recalls of food consumption in the school cafeteria, hand-washing habits and eating habits. Rectal swabs of the new cases and food handlers as well as water and food samples were collected to test potential bacteria and viruses. Norovirus was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR).
A total of 278 cases developed gastrointestinal symptoms in this outbreak, and the overall attack rate was 13.9%. The main symptoms included vomiting (50.0%), abdominal cramps (40.3%), nausea (27.0%), diarrhea (6.8%) and fever (6.8%). Twenty rectal swab samples were detected as Norovirus–positive, including 11 from student cases and 9 from asymptomatic food handlers (non-cases). Among environmental surface samples from the kitchen, 8 samples were also detected as Norovirus-positive. The genotypes of viral strains were the same (GII) in patients, asymptomatic food handlers and environmental surfaces. Other samples, including rectal swabs, water samples and food samples were negative for any bacteria and other tested viruses. Asymptomatic food handlers may have contaminated the cooked food during the food preparation.
The study detected that the outbreak was caused by Norovirus and should be controlled by thorough disinfection and excluding asymptomatic food handlers from food preparation. Early identification of the predominant mode of transmission in this outbreak was necessary to prevent new cases. Furthermore, good hygiene practices such as regular hand washing and efficient daily disinfection should be promoted to prevent such infection and outbreaks.
PMCID: PMC4221699  PMID: 25335780
Norovirus; Acute gastroenteritis; Outbreak; Asymptomatic food handler
24.  Decline in HAV-associated fulminant hepatic failure and liver transplant in children in Argentina after the introduction of a universal hepatitis A vaccination program 
Hepatitis A virus (HAV) infection is a vaccine-preventable disease. The most severe complication in children is fulminant hepatic failure (FHF), estimated to occur in 0.4% of cases; patients with FHF often require a liver transplant (LT). Following another outbreak of HAV infection in Argentina during 2003–2004, a one-dose HAV universal immunization (UI) program was started in 2005, resulting in a reduction in the incidence of HAV infection. We have investigated the impact of HAV UI on the trends in the occurrence of FHF and LT in children.
All pediatric cases of FHF admitted to four pediatric centers in Buenos Aires during March 1993–July 2005 were retrospectively reviewed, and data of cases during August 2005–December 2008 were collected. Information about demography, HAV infections and vaccination status, diagnostic data for FHF using the Pediatric Acute Liver Failure criteria, clinical laboratory results, encephalopathy, the severity of liver disease using the Pediatric End Stage Liver Disease score, assessment of patients on the LT waiting list using King’s College Criteria for LT, treatment given for FHF (pre- and post-transplant), and clinical outcome were collected using a case report form. The frequency and outcomes of HAV-associated FHF and LT cases before and after UI were analyzed.
During the pre-immunization period, March 1993–July 2005, 54.6% (N = 165) of FHF cases were caused by HAV; HAV-associated FHF cases peaked during 2003–2004. During the post-immunization period, August 2005–December 2008, only 27.7% (N = 18) of FHF cases were caused by HAV infection; only one of these patients had received the HAV vaccine (one dose only). The number of HAV-associated FHF cases decreased from 2005, and no cases were reported from November 2006–December 2008. Multivariate analyses showed that the association of FHF with HAV infection rather than other etiologies decreased with increasing age (P = 0.03), UI against HAV (P = 0.002), and anti-actin antibodies (P = 0.002), and increased with increasing weight (P = 0.0004).
The number of children with HAV-associated FHF in Argentina has strongly decreased since the initiation of the UI program. Further monitoring is required to confirm the long-term health and economic benefits of UI against HAV infection.
PMCID: PMC3846416  PMID: 24367225
hepatitis A vaccine; fulminant hepatic failure; immunization
25.  Reducing the Impact of the Next Influenza Pandemic Using Household-Based Public Health Interventions 
PLoS Medicine  2006;3(9):e361.
The outbreak of highly pathogenic H5N1 influenza in domestic poultry and wild birds has caused global concern over the possible evolution of a novel human strain [1]. If such a strain emerges, and is not controlled at source [2,3], a pandemic is likely to result. Health policy in most countries will then be focused on reducing morbidity and mortality.
Methods and Findings
We estimate the expected reduction in primary attack rates for different household-based interventions using a mathematical model of influenza transmission within and between households. We show that, for lower transmissibility strains [2,4], the combination of household-based quarantine, isolation of cases outside the household, and targeted prophylactic use of anti-virals will be highly effective and likely feasible across a range of plausible transmission scenarios. For example, for a basic reproductive number (the average number of people infected by a typically infectious individual in an otherwise susceptible population) of 1.8, assuming only 50% compliance, this combination could reduce the infection (symptomatic) attack rate from 74% (49%) to 40% (27%), requiring peak quarantine and isolation levels of 6.2% and 0.8% of the population, respectively, and an overall anti-viral stockpile of 3.9 doses per member of the population. Although contact tracing may be additionally effective, the resources required make it impractical in most scenarios.
National influenza pandemic preparedness plans currently focus on reducing the impact associated with a constant attack rate, rather than on reducing transmission. Our findings suggest that the additional benefits and resource requirements of household-based interventions in reducing average levels of transmission should also be considered, even when expected levels of compliance are only moderate.
Voluntary household-based quarantine and external isolation are likely to be effective in limiting the morbidity and mortality of an influenza pandemic, even if such a pandemic cannot be entirely prevented, and even if compliance with these interventions is moderate.
Editors' Summary
Naturally occurring variation in the influenza virus can lead both to localized annual epidemics and to less frequent global pandemics of catastrophic proportions. The most destructive of the three influenza pandemics of the 20th century, the so-called Spanish flu of 1918–1919, is estimated to have caused 20 million deaths. As evidenced by ongoing tracking efforts and news media coverage of H5N1 avian influenza, contemporary approaches to monitoring and communications can be expected to alert health officials and the general public of the emergence of new, potentially pandemic strains before they spread globally.
Why Was This Study Done?
In order to act most effectively on advance notice of an approaching influenza pandemic, public health workers need to know which available interventions are likely to be most effective. This study was done to estimate the effectiveness of specific preventive measures that communities might implement to reduce the impact of pandemic flu. In particular, the study evaluates methods to reduce person-to-person transmission of influenza, in the likely scenario that complete control cannot be achieved by mass vaccination and anti-viral treatment alone.
What Did the Researchers Do and Find?
The researchers developed a mathematical model—essentially a computer simulation—to simulate the course of pandemic influenza in a hypothetical population at risk for infection at home, through external peer networks such as schools and workplaces, and through general community transmission. Parameters such as the distribution of household sizes, the rate at which individuals develop symptoms from nonpandemic viruses, and the risk of infection within households were derived from demographic and epidemiologic data from Hong Kong, as well as empirical studies of influenza transmission. A model based on these parameters was then used to calculate the effects of interventions including voluntary household quarantine, voluntary individual isolation in a facility outside the home, and contact tracing (that is, asking infectious individuals to identify people whom they may have infected and then warning those people) on the spread of pandemic influenza through the population. The model also took into account the anti-viral treatment of exposed, asymptomatic household members and of individuals in isolation, and assumed that all intervention strategies were put into place before the arrival of individuals infected with the pandemic virus.
  Using this model, the authors predicted that even if only half of the population were to comply with public health interventions, the proportion infected during the first year of an influenza pandemic could be substantially reduced by a combination of household-based quarantine, isolation of actively infected individuals in a location outside the household, and targeted prophylactic treatment of exposed individuals with anti-viral drugs. Based on an influenza-associated mortality rate of 0.5% (as has been estimated for New York City in the 1918–1919 pandemic), the magnitude of the predicted benefit of these interventions is a reduction from 49% to 27% in the proportion of the population who become ill in the first year of the pandemic, which would correspond to 16,000 fewer deaths in a city the size of Hong Kong (6.8 million people). In the model, anti-viral treatment appeared to be about as effective as isolation when each was used in combination with household quarantine, but would require stockpiling 3.9 doses of anti-viral for each member of the population. Contact tracing was predicted to provide a modest additional benefit over quarantine and isolation, but also to increase considerably the proportion of the population in quarantine.
What Do These Findings Mean?
This study predicts that voluntary household-based quarantine and external isolation can be effective in limiting the morbidity and mortality of an influenza pandemic, even if such a pandemic cannot be entirely prevented, and even if compliance with these interventions is far from uniform. These simulations can therefore inform preparedness plans in the absence of data from actual intervention trials, which would be impossible outside (and impractical within) the context of an actual pandemic. Like all mathematical models, however, the one presented in this study relies on a number of assumptions regarding the characteristics and circumstances of the situation that it is intended to represent. For example, the authors found that the efficacy of policies to reduce the rate of infection vary according to the ease with which a given virus spreads from person to person. Because this parameter (known as the basic reproductive ratio, R0) cannot be reliably predicted for a new viral strain based on past epidemics, the authors note that in an actual influenza pandemic rapid determinations of R0 in areas already involved would be necessary to finalize public health responses in threatened areas. Further, the implementation of the interventions that appear beneficial in this model would require devoting attention and resources to practical considerations, such as how to staff isolation centers and provide food and water to those in household quarantine. However accurate the scientific data and predictive models may be, their effectiveness can only be realized through well-coordinated local, as well as international, efforts.
Additional Information.
Please access these Web sites via the online version of this summary at
• World Health Organization influenza pandemic preparedness page
• US Department of Health and Human Services avian and pandemic flu information site
• Pandemic influenza page from the Public Health Agency of Canada
• Emergency planning page on pandemic flu from the England Department of Health
• Wikipedia entry on pandemic influenza with links to individual country resources (note: Wikipedia is a free Internet encyclopedia that anyone can edit)
PMCID: PMC1526768  PMID: 16881729

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