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1.  Prevalence case-control study of epilepsy in three Burkina Faso villages 
Acta neurologica Scandinavica  2012;126(4):270-278.
To estimate the association between the prevalence of epilepsy and potential risk factors in three Burkina Faso villages.
Three villages were selected based on local reports of high numbers of epilepsy cases and pig-rearing practices. One person aged 7 or older was selected at random from all households of selected concessions for epilepsy screening and blood sampling. Epilepsy was confirmed by a physician using the ILAE definition. The cross-sectional associations between epilepsy and selected factors and sero-response to the antigens of Taenia solium were estimated using a Bayesian hierarchical logistic regression. Prevalence odds ratios (POR) and their 95% Credible Intervals (95%BCI) were estimated.
Of 888 individuals interviewed, 39 of 70 screened positive were confirmed to have epilepsy for a lifetime prevalence of 4.5% (95%CI: 3.3–6.0). The prevalence of epilepsy was associated with a positive reaction to cysticercosis Ag-ELISA serology (POR=3.1, 95% BCI= 1.0;8.3), past pork consumption (POR=9.7, 95% BCI=2.5;37.9), and being salaried or a trader compared to a farmer or housewife (POR=2.9, 95% BCI= 1.2;6.4).
Several factors were associated with prevalent epilepsy, with Ag-ELISA suggesting the presence of neurocysticercosis. The association of epilepsy and some occupations may reflect differences in local attitudes toward epilepsy and should be further explored.
PMCID: PMC4187350  PMID: 22289127
epidemiology; epilepsy; cross-sectional study; cysticercosis; Sub-Saharan Africa
2.  Cystic Echinococcosis in the Province of Álava, North Spain: The Monetary Burden of a Disease No Longer under Surveillance 
Cystic echinococcosis (CE) is endemic in Spain but has been considered non-endemic in the province of Álava, Northern Spain, since 1997. However, Álava is surrounded by autonomous regions with some of the highest CE prevalence proportions in the nation, casting doubts about the current classification. The purpose of this study is to estimate the frequency of CE in humans and animals and to use this data to determine the societal cost incurred due to CE in the Álava population in 2005. We have identified epidemiological and clinical data from surveillance and hospital records, prevalence data in intermediate (sheep and cattle) host species from abattoir records, and economical data from national and regional official institutions. Direct costs (diagnosis, treatment, medical care in humans and condemnation of offal in livestock species) and indirect costs (productivity losses in humans and reduction in growth, fecundity and milk production in livestock) were modelled using the Latin hypercube method under five different scenarios reflecting different assumptions regarding the prevalence of asymptomatic cases and associated productivity losses in humans. A total of 13 human CE cases were reported in 2005. The median total cost (95% credible interval) of CE in humans and animals in Álava in 2005 was estimated to range between €61,864 (95%CI%: €47,304–€76,590) and €360,466 (95%CI: €76,424–€752,469), with human-associated losses ranging from 57% to 93% of the total losses, depending on the scenario used. Our data provide evidence that CE is still very well present in Álava and incurs important cost to the province every year. We expect this information to prove valuable for public health agencies and policy-makers, as it seems advisable to reinstate appropriate surveillance and monitoring systems and to implement effective control measures that avoid the spread and recrudescence of the disease.
Author Summary
Historically, cystic echinococcosis (CE) is one of the most important zoonotic diseases in Spain. The initiation of a number of control campaigns in the second half of the 1980s has led to a substantial reduction of the number of CE infections both in humans and livestock species. As a consequence of this initial success, obligation to report human CE cases was revoked in 1997 in a number of Spanish autonomous regions that were consequently considered non-endemic for CE. This policy has not been translated to livestock species, where the identification of hydatid cysts and the reporting of prevalence data remain compulsory in all national slaughterhouses. We present here an estimation of the human and animal CE associated monetary losses in the province of Álava, North Spain, for the year 2005. Obtained economic data corroborate the epidemiological findings and demonstrate that CE has important socio-economic consequences in Álava. Taking together, our data suggest that surveillance status of CE in Álava (and very likely in other Spanish regions currently classified as non-endemic areas) should be reassessed. The situation also indicates that more accurate and effective methods for detecting and reporting the disease at the regional and national level are greatly needed.
PMCID: PMC4125306  PMID: 25102173
4.  A Systematic Review of the Literature on Cystic Echinococcosis Frequency Worldwide and Its Associated Clinical Manifestations 
A systematic literature review of cystic echinoccocosis (CE) frequency and symptoms was conducted. Studies without denominators, original data, or using one serological test were excluded. Random-effect log-binomial models were run for CE frequency and proportion of reported symptoms where appropriate. A total of 45 and 25 articles on CE frequency and symptoms met all inclusion criteria. Prevalence of CE ranged from 1% to 7% in community-based studies and incidence rates ranged from 0 to 32 cases per 100,000 in hospital-based studies. The CE prevalence was higher in females (Prevalence Proportion Ratio: 1.35 [95% Bayesian Credible Interval: 1.16–1.53]) and increased with age. The most common manifestations of hepatic and pulmonary CE were abdominal pain (57.3% [95% confidence interval [CI]: 37.3–76.1%]) and cough (51.3% [95% CI: 35.7–66.7%]), respectively. The results are limited by the small number of unbiased studies. Nonetheless, the age/gender prevalence differences could be used to inform future models of CE burden.
PMCID: PMC3752796  PMID: 23546806
5.  Is bisphenol-A exposure during pregnancy associated with blood glucose levels or diagnosis of gestational diabetes? 
Recent epidemiological studies indicate bisphenol-A (BPA), an estrogenic chemical used in production of epoxy, polycarbonate and plastic may increase risk of insulin resistance and type 2 diabetes. Exposure to BPA during pregnancy may contribute to development of gestational diabetes mellitus (GDM), a precursor to type 2 diabetes in women. This pilot study examined the association between BPA exposure, fasting blood glucose levels (FBG) and GDM diagnosis during pregnancy. Banked urine samples from 22 cases of GDM and 72 controls were analyzed for total (free BPA + conjugates) urinary BPA concentrations (μg/L). FBG levels (mg/dl) were obtained from 1 h 50 g glucose tolerance tests (GTT) that women underwent for routine GDM screening (mean gestational age=26.6 weeks sd=3.8). Those with an initial screening value ≥135 mg/dl underwent 3-hr 100 g oral GTT. GDM diagnoses were made when the initial screening value was ≥ 200 mg/dl or when values at ≥ 2 time points exceeded 3-hr oral GTT thresholds. Among controls, median FBG levels (mg/dL) did not differ across exposure tertiles, defined according to the distribution of total specific-gravity adjusted urinary BPA concentrations. Logistic regression models controlling for race/ethnicity did not provide evidence of association between BPA exposure and case status across increasing tertiles of BPA exposure (number of GDM cases/controls in tertile 1: 13/24, tertile 2: 6/24 tertile 3: 3/24).. Findings do not support a relationship between total urinary BPA concentrations and altered glucose metabolism during pregnancy. However, due to study limitations findings need to be interpreted with caution.
PMCID: PMC3801171  PMID: 24053363
bisphenol-A; gestational diabetes; glucose; pregnancy
6.  Quality of Life in Patients with Neurocysticercosis in Mexico 
The objective of this study was to compare quality of life measures in patients with neurocysticercosis (NCC) to those of a matched control group. The NCC outpatients and their controls were recruited from two neurology referral hospitals in Mexico City, Mexico during 2007–2008. The quality of life of 224 NCC patients was compared with 224 age-sex-hospital-day matched controls using the short form 12 v2 (SF-12 v2) quality of life survey. Medical chart reviews were also conducted for the NCC outpatients to evaluate presenting clinical manifestations. Compared with the controls, NCC patients had a significantly lower score for each of the eight domains of health evaluated and significantly lower Physical and Mental Component Summary scores. Chart reviews indicated that hydrocephalus (48%), severe headaches (47%), and epilepsy (31%) were the most common clinical manifestations in these NCC outpatients.
PMCID: PMC3083747  PMID: 21540389
7.  Estimating the Non-Monetary Burden of Neurocysticercosis in Mexico 
Neurocysticercosis (NCC) is a major public health problem in many developing countries where health education, sanitation, and meat inspection infrastructure are insufficient. The condition occurs when humans ingest eggs of the pork tapeworm Taenia solium, which then develop into larvae in the central nervous system. Although NCC is endemic in many areas of the world and is associated with considerable socio-economic losses, the burden of NCC remains largely unknown. This study provides the first estimate of disability adjusted life years (DALYs) associated with NCC in Mexico.
DALYs lost for symptomatic cases of NCC in Mexico were estimated by incorporating morbidity and mortality due to NCC-associated epilepsy, and morbidity due to NCC-associated severe chronic headaches. Latin hypercube sampling methods were employed to sample the distributions of uncertain parameters and to estimate 95% credible regions (95% CRs).
In Mexico, 144,433 and 98,520 individuals are estimated to suffer from NCC-associated epilepsy and NCC-associated severe chronic headaches, respectively. A total of 25,341 (95% CR: 12,569–46,640) DALYs were estimated to be lost due to these clinical manifestations, with 0.25 (95% CR: 0.12–0.46) DALY lost per 1,000 person-years of which 90% was due to NCC-associated epilepsy.
This is the first estimate of DALYs associated with NCC in Mexico. However, this value is likely to be underestimated since only the clinical manifestations of epilepsy and severe chronic headaches were included. In addition, due to limited country specific data, some parameters used in the analysis were based on systematic reviews of the literature or primary research from other geographic locations. Even with these limitations, our estimates suggest that healthy years of life are being lost due to NCC in Mexico.
Author Summary
Neurocysticercosis (NCC) is a major public health problem caused by the larvae of the parasite Taenia solium. The condition occurs when humans ingest eggs of the pork tapeworm Taenia solium, which then develop into larvae in the central nervous system. The disease is predominantly found and considered important in Latin American, Asian, and African countries and is associated with a large social and economic burden. Very few studies have been conducted to evaluate the burden of NCC and there are no estimates from Mexico. We estimated the disability adjusted life years (DALYs) lost due to NCC in Mexico incorporating morbidity and mortality due to NCC-associated epilepsy, and morbidity due to NCC-associated severe chronic headaches. NCC-associated epilepsy and severe chronic headaches were estimated to cause a loss of approximately 0.25 healthy year of life per 1,000 persons annually in Mexico. This is the first estimate of DALYs associated with NCC in Mexico. However, this value is likely to be underestimated since only the clinical manifestations of epilepsy and severe chronic headaches were included.
PMCID: PMC3283554  PMID: 22363827
8.  Clinical Manifestations Associated with Neurocysticercosis: A Systematic Review 
The clinical manifestations of neurocysticercosis (NCC) are poorly understood. This systematic review aims to estimate the frequencies of different manifestations, complications and disabilities associated with NCC.
A systematic search of the literature published from January 1, 1990, to June 1, 2008, in 24 different electronic databases and 8 languages was conducted. Meta-analyses were conducted when appropriate.
A total of 1569 documents were identified, and 21 included in the analysis. Among patients seen in neurology clinics, seizures/epilepsy were the most common manifestations (78.8%, 95%CI: 65.1%–89.7%) followed by headaches (37.9%, 95%CI: 23.3%–53.7%), focal deficits (16.0%, 95%CI: 9.7%–23.6%) and signs of increased intracranial pressure (11.7%, 95%CI: 6.0%–18.9%). All other manifestations occurred in less than 10% of symptomatic NCC patients. Only four studies reported on the mortality rate of NCC.
NCC is a pleomorphic disease linked to a range of manifestations. Although definitions of manifestations were very rarely provided, and varied from study to study, the proportion of NCC cases with seizures/epilepsy and the proportion of headaches were consistent across studies. These estimates are only applicable to patients who are ill enough to seek care in neurology clinics and likely over estimate the frequency of manifestations among all NCC cases.
Author Summary
Neurocysticercosis is an infection of the brain with the flatworm Taenia solium which is normally transmitted between humans and pigs. Sometimes, humans can infect other humans and the larva of the parasite can go the brain, causing the disease neurocysticercosis. There has never been a systematic review of what clinical signs are found among people with neurocysticercosis. We conducted a thorough review of the literature to answer this question. We reviewed 1569 and 21 were of a sufficient quality to be included in the final analysis. Among neurocysticercosis patients who are seeking care in neurology clinics, about 79% have seizures/epilepsy, 38% severe headaches, 16% focal deficits and 12% signs of increased intracranial pressure. Several other symptoms were also reported in less than 10% of patients. People with neurocysticercosis who seek care in neurology clinics show a whole range of manifestations. Clinicians should be encouraged to consider neurocysticercosis in their differential diagnosis when a patient presented with one of the symptoms described in this review. This would ultimately improve the estimates of the frequency of symptoms associated with neurocysticercosis.
PMCID: PMC3101170  PMID: 21629722
9.  Assessing the Impact of Misclassification Error on an Epidemiological Association between Two Helminthic Infections 
Polyparasitism can lead to severe disability in endemic populations. Yet, the association between soil-transmitted helminth (STH) and the cumulative incidence of Schistosoma japonicum infection has not been described. The aim of this work was to quantify the effect of misclassification error, which occurs when less than 100% accurate tests are used, in STH and S. japonicum infection status on the estimation of this association.
Methodology/Principal Findings
Longitudinal data from 2276 participants in 50 villages in Samar province, Philippines treated at baseline for S. japonicum infection and followed for one year, served as the basis for this analysis. Participants provided 1–3 stool samples at baseline and 12 months later (2004–2005) to detect infections with STH and S. japonicum using the Kato-Katz technique. Variation from day-to-day in the excretion of eggs in feces introduces individual variations in the sensitivity and specificity of the Kato-Katz to detect infection. Bayesian logit models were used to take this variation into account and to investigate the impact of misclassification error on the association between these infections. Uniform priors for sensitivity and specificity of the diagnostic test to detect the three STH and S. japonicum were used. All results were adjusted for age, sex, occupation, and village-level clustering. Without correction for misclassification error, the odds ratios (ORs) between hookworm, Ascaris lumbricoides, and Trichuris trichiura, and S. japonicum infections were 1.28 (95% Bayesian credible intervals: 0.93, 1.76), 0.91 (95% BCI: 0.66, 1.26), and 1.11 (95% BCI: 0.80, 1.55), respectively, and 2.13 (95% BCI: 1.16, 4.08), 0.74 (95% BCI: 0.43, 1.25), and 1.32 (95% BCI: 0.80, 2.27), respectively, after correction for misclassification error for both exposure and outcome.
The misclassification bias increased with decreasing test accuracy. Hookworm infection was found to be associated with increased 12-month cumulative incidence of S. japonicum infection after correction for misclassification error. Such important associations might be missed in analyses which do not adjust for misclassification errors.
Author Summary
Hookworm, roundworm, and whipworm are collectively known as soil-transmitted helminths. These worms are prevalent in most of the developing countries along with another parasitic infection called schistosomiasis. The tests commonly used to detect infection with these worms are less than 100% accurate. This leads to misclassification of infection status since these tests cannot always correctly indentify infection. We conducted an epidemiological study where such a test, the Kato-Katz technique, was used. In our study we tried to show how misclassification error can influence the association between soil-transmitted helminth infection and schistosomiasis in humans. We used a statistical technique to calculate epidemiological measures of association after correcting for the inaccuracy of the test. Our results show that there is a major difference between epidemiological measures of association before and after the correction of the inaccuracy of the test. After correction of the inaccuracy of the test, soil-transmitted helminth infection was found to be associated with increased risk of acquiring schistosomiasis. This has major public health implications since effective control of one worm can lead to reduction in the occurrence of another and help to reduce the overall burden of worm infection in affected regions.
PMCID: PMC3066162  PMID: 21468317
10.  Factors Associated with the Prevalence of Circulating Antigens to Porcine Cysticercosis in Three Villages of Burkina Faso 
Little is known about porcine cysticercosis in Burkina Faso. We conducted a pilot study to estimate the prevalence of antigens of Taenia solium cysticercosis and to identify associated factors in pigs of three villages in Burkina Faso, selected to represent different pig management practices: one village where pigs are allowed to roam freely (Batondo), one village where pigs are penned part of the time (Pabré) and one village with limited pig farming (Nyonyogo).
Methods/Principal Findings
A clustered random sampling design was used. Data on socio-demographic characteristics (source of drinking water, presence of latrines in the household, type and number of breeding animals) and pig management practices were collected using a standardized questionnaire. Blood samples were collected from one pig per household to determine the presence of antigens of the larval stages of T. solium by the B158/B60 Ag-ELISA. The associations between seropositivity and socio-demographic and pig management practices were estimated using logistic regression. Proportions of 32.5% (95% CI 25.4–40.3), 39.6% (31.9–47.8), and 0% of pigs, were found positive for the presence of circulating antigens of T. solium in Batondo, Pabré, and Nyonyogo, respectively. The results of the logistic regression analyses suggested that people acquire knowledge on porcine cysticercosis following the contamination of their animals. The presence of antigens in the pigs' sera was not associated with the absence of latrines in the household, the source of drinking water or the status of infection in humans but was associated with pig rearing practices during the rainy season.
The results suggest that education of pig farmers is urgently needed to reduce the prevalence of this infection.
Author Summary
Taenia solium cysticercosis is a neglected tropical infection transmitted between humans and pigs. This infection is particularly common in areas where sanitation, hygiene and pig management practices are poor, and can sometimes lead to epilepsy in humans. There is very little information about the importance of this infection in Burkina Faso, even though pork meat is widely consumed in many villages. We conducted a pilot study in three villages: two villages where pig rearing and pork consumption are common (Batondo and Pabré) but with different pig management practices, and one village with limited pig farming and pork consumption (Nyonyogo). Blood tests were done on pigs and information on pig raising was collected from farmers. Our study demonstrated that at least one third of pigs are infected with cysticercosis in villages where they are raised, and, particularly when pigs are left to roam some or all of the time. It also demonstrated that farmers may not be aware of this disease until one of their animals is found to be infected. Thus, the study concluded that there is an urgent need for improving education in order to control this tropical disease.
PMCID: PMC3014946  PMID: 21245913
11.  A Systematic Review of the Frequency of Neurocyticercosis with a Focus on People with Epilepsy 
The objective of this study is to conduct a systematic review of studies reporting the frequency of neurocysticercosis (NCC) worldwide.
Methods/Principal Findings
PubMed, Commonwealth Agricultural Bureau (CAB) abstracts and 23 international databases were systematically searched for articles published from January 1, 1990 to June 1, 2008. Articles were evaluated for inclusion by at least two researchers focusing on study design and methods. Data were extracted independently using standardized forms. A random-effects binomial model was used to estimate the proportion of NCC among people with epilepsy (PWE). Overall, 565 articles were retrieved and 290 (51%) selected for further analysis. After a second analytic phase, only 4.5% of articles, all of which used neuroimaging for the diagnosis of NCC, were reviewed. Only two studies, both from the US, estimated an incidence rate of NCC using hospital discharge data. The prevalence of NCC in a random sample of village residents was reported from one study where 9.1% of the population harboured brain lesions of NCC. The proportion of NCC among different study populations varied widely. However, the proportion of NCC in PWE was a lot more consistent. The pooled estimate for this population was 29.0% (95%CI: 22.9%–35.5%). These results were not sensitive to the inclusion or exclusion of any particular study.
Only one study has estimated the prevalence of NCC in a random sample of all residents. Hence, the prevalence of NCC worldwide remains unknown. However, the pooled estimate for the proportion of NCC among PWE was very robust and could be used, in conjunction with estimates of the prevalence and incidence of epilepsy, to estimate this component of the burden of NCC in endemic areas. The previously recommended guidelines for the diagnostic process and for declaring NCC an international reportable disease would improve the knowledge on the global frequency of NCC.
Author Summary
Neurocysticercosis (NCC) is a parasitic infection of the brain caused by the tapeworm Taenia solium, which infects humans and pigs. There have been increasing case reports and epidemiological studies on this disease, but its global frequency has never been determined, partly due to the fact that blood tests are not very good for the diagnosis of NCC. We present here a systematic review of the literature on the frequency of NCC diagnosed with neuroimaging worldwide. Overall, 565 articles were retrieved and 290 (51%) selected for further review. Of those, only 26 had information valid enough to estimate the frequency of NCC in various populations. Only one study estimated the prevalence of NCC in the general population. The most striking finding was that the proportion of NCC among persons with epilepsy was very consistent and estimated at 29.6% (95%CI: 23.5%–36.1%) from 12 studies conducted in Latin America, Sub-Saharan Africa and Southeast Asia. A reinforcement of the suggested universal guidelines for the diagnostic process, declaring NCC an international reportable disease and standardizing procedures for data collection could improve our understanding of the frequency of NCC worldwide and hence its global burden.
PMCID: PMC2970544  PMID: 21072231
12.  Agriculture Emergencies: A Primer for First Responders 
Over the past several years, the primary focus of emergency preparedness has been on terrorism, and how a CBRNE event would directly affect human health. Limited emphasis has been placed on the direct (eg, zoonotic infections) and indirect (eg, mental health, financial loss) effects that an agricultural emergency event can have on human health outcomes, and how they relate to emergency preparedness. We critically reviewed the resources and information readily accessible to our target audience, emergency responders; the resources included military and civilian books, personal communications, internet sites, GAO reports, and peer-reviewed journals. Among more than 2,000 bioterrorism-related articles, we found 51 that addressed either agroterrorism and/or veterinary public health: 2 cross-sectional studies, 28 review papers, and 21 commentary papers. In order to properly respond to future agriculture emergencies, emergency response professionals need to understand the nature and implications of the event as well as their roles and responsibilities, but the availability of educational and training opportunities is limited. The results of our review are consistent with the hypothesis that more resources, education, and training opportunities should be available to responders as well as to producers, importers and shippers, international travelers, and the general public. Increased education and training will raise awareness among these groups of the relationship between animal and human health.
PMCID: PMC2995339  PMID: 19635003
13.  Spatial Clustering of Porcine Cysticercosis in Mbulu District, Northern Tanzania 
Porcine cysticercosis is caused by a zoonotic tapeworm, Taenia solium, which causes serious disease syndromes in human. Effective control of the parasite requires knowledge on the burden and pattern of the infections in order to properly direct limited resources. The objective of this study was to establish the spatial distribution of porcine cysticercosis in Mbulu district, northern Tanzania, to guide control strategies.
Methodology/Principal Findings
This study is a secondary analysis of data collected during the baseline and follow-up periods of a randomized community trial aiming at reducing the incidence rate of porcine cysticercosis through an educational program. At baseline, 784 randomly selected pig-keeping households located in 42 villages in 14 wards were included. Lingual examination of indigenous pigs aged 2–12 (median 8) months, one randomly selected from each household, were conducted. Data from the control group of the randomized trial that included 21 of the 42 villages were used for the incidence study. A total of 295 pig-keeping households were provided with sentinel pigs (one each) and reassessed for cysticercosis incidence once or twice for 2–9 (median 4) months using lingual examination and antigen ELISA. Prevalence of porcine cysticercosis was computed in Epi Info 3.5. The prevalence and incidence of porcine cysticercosis were mapped at household level using ArcView 3.2. K functions were computed in R software to assess general clustering of porcine cysticercosis. Spatial scan statistics were computed in SatScan to identify local clusters of the infection. The overall prevalence of porcine cysticercosis was 7.3% (95% CI: 5.6, 9.4; n = 784). The K functions revealed a significant overall clustering of porcine cysticercosis incidence for all distances between 600 m and 5 km from a randomly chosen case household based on Ag-ELISA. Lingual examination revealed clustering from 650 m to 6 km and between 7.5 and 10 km. The prevalence study did not reveal any significant clustering by this method. Spatial scan statistics found one significant cluster of porcine cysticercosis prevalence (P = 0.0036; n = 370). In addition, the analysis found one large cluster of porcine cysticercosis incidence based on Ag-ELISA (P = 0.0010; n = 236) and two relatively small clusters of incidence based on lingual examination (P = 0.0012 and P = 0.0026; n = 241). These clusters had similar spatial location and included six wards, four of which were identified as high risk areas of porcine cysticercosis.
This study has identified local clusters of porcine cysticercosis in Mbulu district, northern Tanzania, where limited resources for control of T. solium could be directed. Further studies are needed to establish causes of clustering to institute appropriate interventions.
Author Summary
Taenia solium is a tapeworm that causes two different disease conditions. In its adult stage, it inhabits the small intestine of human, a condition known as taeniosis, which is characterised by mild symptoms including abdominal disconfort. In the larval stage, T. solium can infect humans and various animal species, mainly pigs, causing cysticercosis. Taeniosis is acquired through consumption of inadequately cooked infected meat, while cysticercosis is acquired through ingestion of tapeworm eggs in foodstuffs contaminated with faeces from a human tapeworm carrier. Cysticercosis of human central nervous tissues (neurocysticercosis) causes serious syndromes such as epilepsy. Transmission of T. solium is facilitated by several factors such as presence of tapeworm carriers, poor sanitation and poor pig husbandry, which allow pigs to access human faeces. Nevertheless, the role of these factors in parasite transmission may vary with different cultural settings. Following an incidence and a prevalence studies in a rural area of northern Tanzania, there was a significant spatial clustering of porcine cysticerocis, suggesting focal distribution of transmission risk factors, which could be targeted for interventions. The study also revealed that despite the low sensitivity of the lingual examination method to detect porcine cysticercosis, it could highlight the potential ‘hotspots’ of the infection.
PMCID: PMC2850315  PMID: 20386601
14.  Accuracy of Serological Testing for the Diagnosis of Prevalent Neurocysticercosis in Outpatients with Epilepsy, Eastern Cape Province, South Africa 
Few studies have estimated prevalence of neurocysticercosis (NCC) among persons with epilepsy in sub-Saharan Africa. While the limitations of serological testing in identification of NCC are well known, the characteristics of persons who are misdiagnosed based on serology have not been explored. The first objective of this pilot study was to estimate the prevalence of NCC in epilepsy outpatients from an area of South Africa endemic for cysticercosis. The second objective was to estimate the accuracy of serological testing in detecting NCC in these outpatients and characterize sources of disagreement between serology and neuroimaging.
Methodology/Principal Findings
All out-patients aged 5 or older attending the epilepsy clinic of St. Elizabeth's Hospital in Lusikisiki, Eastern Cape Province, between July 2004 and April 2005 were invited to participate. Epidemiological data were collected by local study staff using a standardized questionnaire. Blood samples were tested by ELISA for antibody and antigen for Taenia solium. Four randomly chosen, consenting participants were transported each week to Mthatha for brain CT scan. The proportion of persons with epilepsy attending St. Elizabeth clinic with CT-confirmed NCC was 37% (95% CI: 27%–48%). Using CT as the gold standard, the sensitivity and specificity of antibody testing for identifying NCC were 54.5% (36.4%–71.9%) and 69.2% (52.4%–83.0%), respectively. Sensitivity improved to 78.6% (49.2%–95.3%) for those with active lesions. Sensitivity and specificity of antigen testing were considerably poorer. Compared to false negatives, true positives more often had active lesions. False positives were more likely to keep pigs and to have seizure onset within the past year than were true negatives.
The prevalence of NCC in South African outpatients with epilepsy is similar to that observed in other countries where cysticercosis is prevalent. Errors in classification of NCC using serology alone may reflect the natural history of NCC.
Author Summary
Epilepsy is a significant contributor to morbidity world-wide in persons of all ages. Little is known, however, about its causes. In the developing world, parasitic infections of the brain, in particular Taenia solium neurocysticercosis (NCC) are thought to be important factors. Determining whether or not there is infection in the brain is difficult since to be certain, specialized imaging studies, such as CT scans, are required. These are expensive and not widely available. In addition, they are not appropriate for use in large, population-based studies. Thus, blood tests for evidence of infection with T. solium are often done instead to estimate the presence of NCC. In this study's population of persons with epilepsy being seen at a hospital out-patient clinic in South Africa, 37% had CT evidence of NCC, a percentage similar to that reported in other developing countries. The study also found that blood tests were not generally useful compared to CT for correctly identifying those persons who did or did not have NCC, and thus, they cannot be relied upon for field studies of NCC.
PMCID: PMC2780704  PMID: 19997629
15.  Seroprevalence to the Antigens of Taenia solium Cysticercosis among Residents of Three Villages in Burkina Faso: A Cross-Sectional Study 
There is limited published information on the prevalence of human cysticercosis in West Africa. The aim of this pilot study was to estimate the prevalence of Taenia solium cysticercosis antigens in residents of three villages in Burkina Faso.
Methods/Principal Findings
Three villages were selected: The village of Batondo, selected to represent villages where pigs are allowed to roam freely; the village of Pabré, selected to represent villages where pigs are usually confined; and the village of Nyonyogo, selected because of a high proportion of Muslims and limited pig farming. Clustered random sampling was used to select the participants. All participants were asked to answer an interview questionnaire on socio-demographic characteristics and to provide a blood sample. The sera were analysed using an AgELISA. The prevalence of “strong” seropositive results to the presence of antigens of the larval stages of T. solium was estimated as 10.3% (95%CI: 7.1%–14.3%), 1.4% (0.4%–3.5%) and 0.0% (0.0%–2.1%) in the 763 participants who provided a blood sample in Batondo, Pabré and Nyonyogo, respectively. The prevalence of “weak” seropositive test results to the presence of antigens of the larval stages of T. solium was 1.3% (0.3%–3.2%), 0.3% (0.0%–1.9%) and 4.5% (2.0%–8.8%) in Batondo, Pabré and Nyonyogo, respectively. The multivariate logistic regression, which included only Batondo and Pabré, showed that village, gender, and pork consumption history were associated with AgELISA seroprevalence.
This study illustrates two major points: 1) there can be large variation in the prevalence of human seropositivity to the presence of the larval stages of T. solium cysticercosis among rural areas of the same country, and 2) the serological level of the antigen, not just whether it is positive or negative, must be considered when assessing prevalence of human cysticercosis antigens.
Author Summary
Taenia solium cysticercosis is a neglected tropical zoonosis transmitted between humans and pigs. This infection is particularly prevalent in areas where sanitation, hygiene and pig management practices are poor. There is very little information about the importance of this infection in West Africa, even though pork meat is widely consumed in many areas. This pilot study, conducted in three villages of Burkina Faso, demonstrated that people living in areas where pigs are raised were more likely to be infected with cysticercosis than people living in a Muslim village in which there were very few pigs. It also demonstrated variation in the level of infection between the two villages where pigs were raised. Finally, the results suggest that the source of infection in these three villages may differ. These results are significant because they show that there is clustering of infection within villages, even if they are geographically very close to one another. This should encourage future researchers not to combine data from several villages into one summary value. In addition, more work is needed to better describe different potential sources of infection among villages.
PMCID: PMC2775160  PMID: 19936298
16.  The Disease Burden of Taenia solium Cysticercosis in Cameroon 
Taenia solium cysticercosis is an important zoonosis in many developing countries. Human neurocysticercosis is recognised as an important cause of epilepsy in regions where the parasite occurs. However, it is largely underreported and there is a lack of data about the disease burden. Because a body of information on human and porcine cysticercosis in Cameroon is becoming available, the present study was undertaken to calculate the impact of this neglected zoonosis.
Both the cost and Disability Adjusted Life Year (DALY) estimations were applied. All necessary parameters were collected and imported in R software. Different distributions were used according to the type of information available for each of the parameters.
Based on a prevalence of epilepsy of 3.6%, the number of people with neurocysticercosis-associated epilepsy was estimated at 50,326 (95% CR 37,299–65,924), representing 1.0% of the local population, whereas the number of pigs diagnosed with cysticercosis was estimated at 15,961 (95% CR 12,320–20,044), which corresponds to 5.6% of the local pig population. The total annual costs due to T. solium cysticercosis in West Cameroon were estimated at 10,255,202 Euro (95% CR 6,889,048–14,754,044), of which 4.7% were due to losses in pig husbandry and 95.3% to direct and indirect losses caused by human cysticercosis. The monetary burden per case of cysticercosis amounts to 194 Euro (95% CR 147–253). The average number of DALYs lost was 9.0 per thousand persons per year (95% CR 2.8–20.4).
This study provides an estimation of the costs due to T. solium cysticercosis using country-specific parameters and including the human as well as the animal burden of the zoonotic disease. A comparison with a study in South Africa indicates that the cost of inactivity, influenced by salaries, plays a predominant role in the monetary burden of T. solium cysticercosis. Therefore, knowing the salary levels and the prevalence of the disease might allow a rapid indication of the total cost of T. solium cysticercosis in a country. Ascertaining this finding with additional studies in cysticercosis-endemic countries could eventually allow the estimation of the global disease burden of cysticercosis. The estimated number of DALYs lost due to the disease was higher than estimates already available for some other neglected tropical diseases. The total estimated cost and number of DALYs lost probably underestimate the real values because the estimations have been based on epilepsy as the only symptom of cysticercosis.
Author Summary
Taenia solium cysticercosis is a zoonotic disease occurring in many developing countries. A relatively high prevalence in humans and pigs has been reported in several parts of the world, but insufficient data are available on the disease burden. Disease impact assessment needs detailed information on well-defined epidemiological and economic parameters. Our work conducted in West Cameroon over several years allowed us to collect the necessary information to estimate the impact of the parasite on the human and animal populations in this area using both cost and Disability Adjusted Life Year (DALY) estimations. This study identified the professional inactivity caused by the disease as the major loss factor in comparison to the cost of health care and losses due to infected pigs. These findings should allow a simpler estimation of the global disease burden based on information on salary levels and human cysticercosis prevalence in endemic areas of the world. In addition, the number of DALYs lost was higher than estimates already available for some other neglected tropical diseases in sub-Saharan Africa.
PMCID: PMC2656639  PMID: 19333365
17.  Prevalence of Schistosoma japonicum infection of Oncomelania quadrasi snail colonies in 50 irrigated and rain-fed villages of Samar Province, the Philippines 
Acta tropica  2007;105(3):235-241.
A cross-sectional survey of Oncomelania quadrasi, the intermediate host for Schistosoma japonicum, was conducted between 2004 and 2005 in 50 villages of the Province of Samar, the Philippines. The villages were classified as rain-fed (25) or with some man-made irrigation system (25). The primary objective was to identify all snail colony sites in the 50 villages and to compare snail population density and S. japonicum infection prevalence between the two types of villages. The presence of snail colonies was surveyed along streams, springs, various canals and swampy areas or grass land. A total of 198 colony sites were identified out of the 845 sites surveyed. Of these, a sufficient number of O. quadrasi snails were identified to measure density and infection in 147 sites. Density of O. quadrasi was remarkably uniform across habitats and there were no significant differences across habitats and between village type. The prevalence of infected snails showed more variability among habitats. Indeed, there was an interaction between the type of habitat and the type of village with irrigated villages being associated with a prevalence proportion ratio of 5.76 (1.31, 25.42) as compared to rain-fed villages among streams and springs. No such association was found among other habitats. The results suggest that once a suitable habitat exists, O. quadrasi populations establish and reach a plateau density. These results are discussed in light of possible ecological measures of control.
PMCID: PMC2293956  PMID: 18207119
Oncomelania; schistosomiasis; irrigation; the Philippines
18.  Population Genetics of Schistosoma japonicum within the Philippines Suggest High Levels of Transmission between Humans and Dogs 
Schistosoma japonicum, which remains a major public health problem in the Philippines and mainland China, is the only schistosome species for which zoonotic transmission is considered important. While bovines are suspected as the main zoonotic reservoir in parts of China, the relative contributions of various non-human mammals to S. japonicum transmission in the Philippines remain to be determined. We examined the population genetics of S. japonicum in the Philippines in order to elucidate transmission patterns across host species and geographic areas.
Methodology/Principal Findings
S. japonicum miracidia (hatched from eggs within fecal samples) from humans, dogs, pigs and rats, and cercariae shed from snail-intermediate hosts, were collected across two geographic areas of Samar Province. Individual isolates were then genotyped using seven multiplexed microsatellite loci. Wright's FST values and phylogenetic trees calculated for parasite populations suggest a high frequency of parasite gene-flow across definitive host species, particularly between dogs and humans. Parasite genetic differentiation between areas was not evident at the definitive host level, possibly suggesting frequent import and export of infections between villages, although there was some evidence of geographic structuring at the snail–intermediate host level.
These results suggest very high levels of transmission across host species, and indicate that the role of dogs should be considered when planning control programs. Furthermore, a regional approach to treatment programs is recommended where human migration is extensive.
Author Summary
Schistosomiasis is a disease caused by parasitic worms known as schistosomes, which infect about 200 million people worldwide. In the Philippines, as in China, the species of schistosome (Schistosoma japonicum) which causes the disease infects not only humans, but also many other species of mammals. In China, bovines are thought to be particularly important for harboring and transmitting S. japonicum, whereas in the Philippines infections in bovines are relatively rare. However, dogs, rats and pigs are often infected with S. japonicum in the Philippines, although the extent to which infections in these animals may give rise to human infections is unclear. To help answer this question, we characterized the genetic variation of the parasite in Samar province of the Philippines, and found that S. japonicum samples from humans, dogs, rats and pigs were genetically very similar, with no significant genetic difference between samples from humans and dogs. This suggests that in the Philippines this parasite is frequently transmitted between different mammalian species, particularly between dogs and humans. Reducing levels of infections in dogs may therefore help to reduce infections in humans. The results also suggest high levels of transmission between geographic areas, thus regional co-ordination of treatment programs is recommended.
PMCID: PMC2582952  PMID: 19030225
19.  Decision-Model Estimation of the Age-Specific Disability Weight for Schistosomiasis Japonica: A Systematic Review of the Literature 
Schistosomiasis is among the most prevalent parasitic infections worldwide. However, current Global Burden of Disease (GBD) disability-adjusted life year estimates indicate that its population-level impact is negligible. Recent studies suggest that GBD methodologies may significantly underestimate the burden of parasitic diseases, including schistosomiasis. Furthermore, strain-specific disability weights have not been established for schistosomiasis, and the magnitude of human disease burden due to Schistosoma japonicum remains controversial. We used a decision model to quantify an alternative disability weight estimate of the burden of human disease due to S. japonicum. We reviewed S. japonicum morbidity data, and constructed decision trees for all infected persons and two age-specific strata, <15 years (y) and ≥15 y. We conducted stochastic and probabilistic sensitivity analyses for each model. Infection with S. japonicum was associated with an average disability weight of 0.132, with age-specific disability weights of 0.098 (<15 y) and 0.186 (≥15 y). Re-estimated disability weights were seven to 46 times greater than current GBD measures; no simulations produced disability weight estimates lower than 0.009. Nutritional morbidities had the greatest contribution to the S. japonicum disability weight in the <15 y model, whereas major organ pathologies were the most critical variables in the older age group. GBD disability weights for schistosomiasis urgently need to be revised, and species-specific disability weights should be established. Even a marginal increase in current estimates would result in a substantial rise in the estimated global burden of schistosomiasis, and have considerable implications for public health prioritization and resource allocation for schistosomiasis research, monitoring, and control.
Author Summary
Schistosomiasis is a parasitic infection caused by a flatworm that disproportionately affects the world's poorest populations. Schistosomiasis is one of the most common infections worldwide, affecting over 207 million people in 76 countries. Current international estimates indicate that schistosomiasis has a minimal impact at the population level. This has contributed to its low prioritization in global health and subsequent resource allocation for disease control. However, recent studies indicate that these measures underestimate the extent of neglected tropical diseases, including schistosomiasis. Despite World Health Organization recommendations, the burden of schistosomiasis has not been re-examined in over a decade, and there are no established estimates for different types of schistosomiasis. The impact of symptoms associated with the Asian strain, Schistosoma japonicum, remains controversial. This study was conducted to provide an alternate measure of the burden of S. japonicum. We reviewed the literature and calculated a summary estimate for S. japonicum which was seven to 46 times greater than current measures for schistosomiasis. Findings suggest that current measures severely underestimate the extent of schistosomiasis, and urgently need to be revised. Further research is needed to examine the burden of schistosomiasis and other forgotten tropical diseases affecting the world's poorest people in endemic countries.
PMCID: PMC2254314  PMID: 18320018
20.  Multi-Host Transmission Dynamics of Schistosoma japonicum in Samar Province, the Philippines 
PLoS Medicine  2008;5(1):e18.
Among the 6.7 million people living in areas of the Philippines where infection with Schistosoma japonicum is considered endemic, even within small geographical areas levels of infection vary considerably. In general, the ecological drivers of this variability are not well described. Unlike other schistosomes, S. japonicum is known to infect several mammalian hosts. However, the relative contribution of different hosts to the transmission cycle is not well understood. Here, we characterize the transmission dynamics of S. japonicum using data from an extensive field study and a mathematical transmission model.
Methods and Findings
In this study, stool samples were obtained from 5,623 humans and 5,899 potential nonhuman mammalian hosts in 50 villages in the Province of Samar, the Philippines. These data, with variable numbers of samples per individual, were adjusted for known specificities and sensitivities of the measurement techniques before being used to estimate the parameters of a mathematical transmission model, under the assumption that the dynamic transmission processes of infection and recovery were in a steady state in each village. The model was structured to allow variable rates of transmission from different mammals (humans, dogs, cats, pigs, domesticated water buffalo, and rats) to snails and from snails to mammals. First, we held transmission parameters constant for all villages and found that no combination of mammalian population size and prevalence of infectivity could explain the observed variability in prevalence of infection between villages. We then allowed either the underlying rate of transmission (a) from snails to mammals or (b) from mammals to snails to vary by village. Our data provided substantially more support for model structure (a) than for model structure (b). Fitted values for the village-level transmission intensity from snails to mammals appeared to be strongly spatially correlated, which is consistent with results from descriptive hierarchical analyses.
Our results suggest that the process of acquiring mammalian S. japonicum infection is more important in explaining differences in prevalence of infection between villages than the process of snails becoming infected. Also, the contribution from water buffaloes to human S. japonicum infection in the Philippines is less important than has been recently observed for bovines in China. These findings have implications for the prioritization of mitigating interventions against S. japonicum transmission.
Obtaining schistosome infection data from thousands of humans and mammalian hosts in the Philippines, Steven Riley and colleagues find that mammalian acquisition, rather than transmission to snails, drives prevalence.
Editors' Summary
Parasitic worms called schistosomes infect about 200 million people worldwide. Different schistosome species are common in different parts of the world. Schistosoma japonicum, for example, is restricted to the Pacific region. In the Philippines, 6.7 million people live in areas where this parasite is endemic (constantly present). S. japonicum has a complex life cycle that starts with the parasite reproducing in freshwater snails. Free-swimming infectious parasites emerge from the snails and which burrow into the skin of people and other mammals (most schistosome species infect only people) when they swim in infected water. The parasites migrate to the veins draining the gut, where they mature into adult worms, mate, and lay eggs, some of which pass into the feces and back into the water where they hatch and infect fresh snails. Infection with S. japonicum does not kill many people but it causes serious health problems, including liver, lung, and gut damage.
Why Was This Study Done?
Schistosome infections can be cured with inexpensive drugs, but people living in endemic countries usually become reinfected. The only way to avoid this problem is to eliminate the parasite in the environment, but to do so the relative contributions of snails, people, and other mammals to the transmission cycle need to be understood. Villages in the Philippines have very different levels of infection with S. japonicum. This variation suggests that the location of snail colonies and water courses and the behavior of the parasite's mammalian hosts (for example, their contact with water and their sanitary habits) affect the efficiency of S. japonicum transmission. Knowing which of these factors are the most important would help public-health officials instigate effective interventions to reduce infection rates. In this study, the researchers devise a mathematical model of S. japonicum transmission and use information on the number of people and other mammals infected in several villages in the Philippines to find out what drives inter-village variability in infection.
What Did the Researchers Do and Find?
The researchers counted schistosome eggs in human and nonhuman mammalian feces collected in 50 villages in the Philippines (about 11,500 samples in total) and used these counts to estimate the parameters (values such as the rate of transmission from snails to people) for an S. japonicum transmission model. They then asked whether the proportion of the human population infected with S. japonicum predicted by the model matched actual data on infection levels in the villages. When they assumed that the transmission parameters were the same in all the villages, the variation in the number of mammalian hosts in each village could not explain the observed variation among villages in human infection levels. The researchers, therefore, tested two slightly more complex models in which the underlying rate of transmission from snails to mammals or from mammals to snails varied between villages to reflect different environmental conditions in each village. The first of these models fitted the available data best and also showed that cats, dogs, pigs, and water buffalo were less susceptible to infection with S. japonicum than people but that rats were more susceptible.
What Do These Findings Mean?
These findings suggest that the snail-to-mammal side of the S. japonicum life cycle affects the inter-village variability in human schistosome infection more than the mammal-to-snail side. The findings also indicate that the contribution of water buffaloes to human S. japonicum infection in the Philippines is not particularly important. This contrasts with a recent study that identified water buffaloes as the major mammalian reservoir for S. japonicum in China. As with all mathematical models, the findings of this one depend on the assumptions made to build the model. Nevertheless, they suggest that interventions to reduce the size of the snail population and the exposure of mammals to parasite-containing water might reduce human infection levels more effectively than interventions that interrupt other parts of the parasite's life cycle. These results also suggest that further studies of the transmission of S. japonicum by water buffalo are needed before efforts are dedicated to treat or vaccinate water buffalo as a control measure against human S. japonicum infection.
Additional Information.
Please access these Web sites via the online version of this summary at
The MedlinePlus encyclopedia has a page on schistosomiasis (in English and Spanish)
The US Centers for Disease Control and Prevention provides information for the public and professionals on schistosomiasis
The World Health Organization provides information on schistosomiasis and research into its control
PMCID: PMC2211559  PMID: 18215106
21.  A cross-sectional study of the prevalence of intensity of infection with Schistosoma japonicum in 50 irrigated and rain-fed villages in Samar Province, the Philippines 
BMC Public Health  2006;6:61.
Few studies have described heterogeneity in Schistosoma japonicum infection intensity, and none were done in Philippines. The purpose of this report is to describe the village-to-village variation in the prevalence of two levels of infection intensity across 50 villages of Samar Province, the Philippines.
This cross-sectional study was conducted in 25 rain-fed and 25 irrigated villages endemic for S. japonicum between August 2003 and November 2004. Villages were selected based on irrigation and farming criteria. A maximum of 35 eligible households were selected per village. Each participant was asked to provide stool samples on three consecutive days. All those who provided at least one stool sample were included in the analysis. A Bayesian three category outcome hierarchical cumulative logit regression model with adjustment for age, sex, occupation and measurement error of the Kato-Katz technique was used for analysis.
A total of 1427 households and 6917 individuals agreed to participate in the study. A total of 5624 (81.3%) participants provided at least one stool sample. The prevalences of those lightly and at least moderately infected varied from 0% (95% Bayesian credible interval (BCI): 0%–3.1%) to 45.2% (95% BCI: 36.5%–53.9%) and 0% to 23.0% (95% BCI: 16.4%–31.2%) from village-to-village, respectively. Using the 0–7 year old group as a reference category, the highest odds ratio (OR) among males and females were that of being aged 17–40-year old (OR = 8.76; 95% BCI: 6.03–12.47) and 11–16-year old (OR = 8.59; 95% BCI: 4.74–14.28), respectively. People who did not work on a rice farm had a lower prevalence of infection than those working full time on a rice farm. The OR for irrigated villages compared to rain-fed villages was 1.41 (95% BCI: 0.50–3.21).
We found very important village-to-village variation in prevalence of infection intensity. This variation is probably due to village-level variables other than that explained by a crude classification of villages into the irrigated and non-irrigated categories. We are planning to capture this spatial heterogeneity by updating our initial transmission dynamics model with the data reported here combined with 1-year post-treatment follow-up of study participants.
PMCID: PMC1421391  PMID: 16526960
22.  Towards an understanding of barriers to condom use in rural Benin using the Health Belief Model: A cross sectional survey 
BMC Public Health  2005;5:8.
HIV/AIDS is the most dramatic epidemic of the century that has claimed over two decade more than 3 million deaths. Sub Saharan Africa is heavily affected and accounts for nearly 70% of all cases. Despite awareness campaigns, prevention measures and more recently promotion of anti viral regimens, the prevalence of cases and deaths is still rising and the prevalence of systematic condom use remains low, especially in rural areas. This study identifies barriers to condom use based on the Health Belief Model (HBM) in Benin, West Africa.
The study was a cross-sectional survey conducted from June to July 2002. Two hundred fifty one (251) individuals were interviewed using a structured questionnaire adapted from a standardized WHO/GAP questionnaire. A logistic regression was used to identify factors associated with condom use.
In spite of satisfactory knowledge on HIV/AIDS transmission, participants are still at high risk of contracting the infection. Sixty three (63) percents of the interviewees reported being able to recognize infected people, and condom use during the last occasional intercourse was declared by only 36.8% of males and 47.5% of females. Based on the HBM, failure to use condom was related to its perceived lack of efficacy [OR = 9.76 (3.71–30.0)] and perceived quality [OR = 3.61 (1.31–9.91)].
This study identifies perceived efficacy (incomplete protective effect) and perceived utilization-related problem (any reported problem using condoms) as the main barriers to condom use. Hence, preventions strategies based on increasing perceived risk, perceived severity or adequate knowledge about HIV/AIDS may not be sufficient to induce condom use. These data will be useful in designing and improving HIV/AIDS prevention outreach programs in Sub Saharan Africa.
PMCID: PMC547902  PMID: 15663784
23.  The average cost of measles cases and adverse events following vaccination in industrialised countries 
BMC Public Health  2002;2:22.
Even though the annual incidence rate of measles has dramatically decreased in industrialised countries since the implementation of universal immunisation programmes, cases continue to occur in countries where endemic measles transmission has been interrupted and in countries where adequate levels of immunisation coverage have not been maintained. The objective of this study is to develop a model to estimate the average cost per measles case and per adverse event following measles immunisation using the Netherlands (NL), the United Kingdom (UK) and Canada as examples.
Parameter estimates were based on a review of the published literature. A decision tree was built to represent the complications associated with measles cases and adverse events following imminisation. Monte-Carlo Simulation techniques were used to account for uncertainty.
From the perspective of society, we estimated the average cost per measles case to be US$276, US$307 and US$254 for the NL, the UK and Canada, respectively, and the average cost of adverse events following immunisation per vaccinee to be US$1.43, US$1.93 and US$1.51 for the NL, UK and Canada, respectively.
These average cost estimates could be combined with incidence estimates and costs of immunisation programmes to provide estimates of the cost of measles to industrialised countries. Such estimates could be used as a basis to estimate the potential economic gains of global measles eradication.
PMCID: PMC128813  PMID: 12241559
24.  Comparison of methods of sampling for Toxocara species and fecal coliforms in an outdoor day care environment 
To compare three sampling methods and to pretest methods for the determination of fecal coliform (FC) counts and Toxocara species from sand in the day care outdoor environment.
The sand samples were obtained from the play area and the sandbox of a day care centre and examined for the presence of FC and Toxocara species, the common roundworm of dogs and cats. The sampling methods included random selection and two types of judgement methods. The latter included one method where domestic animals were judged to be likely to defecate and the other where children would be likely to be playing. In addition, to obtain a global estimate of contamination, the entire areas of both the sandbox and the play area were sampled on the last day.
Outdoor day care environment.
The most representative levels of bacterial contamination and Toxocara species originated from the combined sample of the entire surface areas rather than from any separate random or judgement method of sampling. FCs were found in all sampled areas of the sandbox (median 910 FCs/g of sand) and of the play area (median 350 FCs/g of sand). Toxocara species were recovered from a number of areas in both the sandbox and the play area.
Research on environmental microbial contamination of outdoor day care settings would benefit from the application of standardized and validated sampling and laboratory methods.
PMCID: PMC3250911  PMID: 22346537
Contamination; Day care centre; Environment; Fecal coliforms; Methodology; Toxocara species

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