On November 19, 2001, a case of inhalational anthrax was identified in a 94-year-old Connecticut woman, who later died. We conducted intensive surveillance for additional anthrax cases, which included collecting data from hospitals, emergency departments, private practitioners, death certificates, postal facilities, veterinarians, and the state medical examiner. No additional cases of anthrax were identified. The absence of additional anthrax cases argued against an intentional environmental release of Bacillus anthracis in Connecticut and suggested that, if the source of anthrax had been cross-contaminated mail, the risk for anthrax in this setting was very low. This surveillance system provides a model that can be adapted for use in similar emergency settings.

TOC summary: Decreased hospitalization rates suggest decline in complications from Helicobacter pylori infection.

Infection with Helicobacter pylori increases the risk for peptic ulcer disease (PUD) and its complications. To determine whether hospitalization rates for PUD have declined since antimicrobial drugs to eradicate H. pylori became available, we examined 1998–2005 hospitalization records (using the Nationwide Inpatient Sample) in which the primary discharge diagnosis was PUD. Hospitalizations for which the diagnosis was H. pylori infection were also considered. The age-adjusted hospitalization rate for PUD decreased 21% from 71.1/100,000 population (95% confidence interval [CI] 68.9–73.4) in 1998 to 56.5/100,000 in 2005 (95% CI 54.6–58.3). The hospitalization rate for PUD was highest for adults >65 years of age and was higher for men than for women. The age-adjusted rate was lowest for whites and declined for all racial/ethnic groups, except Hispanics. The age-adjusted H. pylori hospitalization rate also decreased. The decrease in PUD hospitalization rates suggests that the incidence of complications caused by H. pylori infection has declined.

Pneumococcal prevention strategies should be emphasized during future influenza pandemics.

A critical issue during the 2009 influenza A (H1N1) pandemic was determining the appropriate duration of time individuals with influenza-like illness (ILI) should remain isolated to reduce onward transmission while limiting societal disruption. Ideally this is based on knowledge of the relative infectiousness of ill individuals at each point during the course of the infection. Data on 261 clinically apparent pH1N1 infector-infectee pairs in households, from 7 epidemiological studies conducted in the United States early in 2009, were analyzed to estimate the distribution of times from symptom onset in an infector to symptom onset in the household contacts they infect (mean, 2.9 days, not correcting for tertiary transmission). Only 5% of transmission events were estimated to take place >3 days after the onset of clinical symptoms among those ill with pH1N1 virus. These results will inform future recommendations on duration of isolation of individuals with ILI.

Rocky Mountain spotted fever (RMSF), a potentially fatal tick-borne infection caused by Rickettsia rickettsii, is considered a notifiable condition in the United States. During 2000 to 2007, the annual reported incidence of RMSF increased from 1.7 to 7 cases per million persons from 2000 to 2007, the highest rate ever recorded. American Indians had a significantly higher incidence than other race groups. Children 5–9 years of age appeared at highest risk for fatal outcome. Enzyme-linked immunosorbent assays became more widely available beginning in 2004 and were used to diagnose 38% of cases during 2005–2007. The proportion of cases classified as confirmed RMSF decreased from 15% in 2000 to 4% in 2007. Concomitantly, case fatality decreased from 2.2% to 0.3%. The decreasing proportion of confirmed cases and cases with fatal outcome suggests that changes in diagnostic and surveillance practices may be influencing the observed increase in reported incidence rates.

Summary: Seafood is part of a healthful diet, but seafood consumption is not risk-free. Seafood is responsible for an important proportion of food-borne illnesses and outbreaks in the United States. Seafood-associated infections are caused by a variety of bacteria, viruses, and parasites; this diverse group of pathogens results in a wide variety of clinical syndromes, each with its own epidemiology. Some seafood commodities are inherently more risky than others, owing to many factors, including the nature of the environment from which they come, their mode of feeding, the season during which they are harvested, and how they are prepared and served. Prevention of seafood-associated infections requires an understanding not only of the etiologic agents and seafood commodities associated with illness but also of the mechanisms of contamination that are amenable to control. Defining these problem areas, which relies on surveillance of seafood-associated infections through outbreak and case reporting, can lead to targeted research and help to guide control efforts. Coordinated efforts are necessary to further reduce the risk of seafood-associated illnesses. Continued surveillance will be important to assess the effectiveness of current and future prevention strategies.

Through July 2009, a total of 43,677 laboratory-confirmed cases of influenza A pandemic (H1N1) 2009 were reported in the United States, which is likely a substantial underestimate of the true number. Correcting for under-ascertainment using a multiplier model, we estimate that 1.8 million–5.7 million cases occurred, including 9,000–21,000 hospitalizations.

Infected persons had slept in an infested cabin.

In February 2006, a diagnosis of sylvatic epidemic typhus in a counselor at a wilderness camp in Pennsylvania prompted a retrospective investigation. From January 2004 through January 2006, 3 more cases were identified. All had been counselors at the camp and had experienced febrile illness with myalgia, chills, and sweats; 2 had been hospitalized. All patients had slept in the same cabin and reported having seen and heard flying squirrels inside the wall adjacent to their bed. Serum from each patient had evidence of infection with Rickettsia prowazekii. Analysis of blood and tissue from 14 southern flying squirrels trapped in the woodlands around the cabin indicated that 71% were infected with R. prowazekii. Education and control measures to exclude flying squirrels from housing are essential to reduce the likelihood of sylvatic epidemic typhus.

Postexposure prophylaxis may avert Q fever illness and death when the probability of exposure is above the population-specific threshold point.

Coxiella burnetii is a category B bioterrorism agent. We numerically evaluated the risks and benefits from postexposure prophylaxis (PEP) after an intentional release of C. burnetii to the general population, pregnant women, and other high-risk populations. For each group, we constructed a decision tree to estimate illness and deaths averted by use of PEP/100,000 population. We calculated the threshold points at which the number of PEP-related adverse events was equal to the cases averted. PEP was defined as doxycycline (100 mg 2×/day for 5 days), except for pregnant women, where we assumed a PEP of trimethoprim-sulfamethoxazole (160 mg/800 mg 2×/day) for the duration of the pregnancy. PEP would begin 8–12 days postexposure. On the basis of upper-bound probability estimates of PEP-related adverse events for doxycycline, we concluded that the risk for Q fever illness outweighs the risk for antimicrobial drug–related adverse events when the probability of C. burnetii exposure is >7% (pregnant women using trimethoprim-sulfamethoxazole = 16%).

Scrub typhus is likely endemic in Palau.

Scrub typhus, caused by Orientia tsutsugamushi, is a severe febrile illness transmitted to humans by trombiculid mites, which normally feed on rodents. The first known outbreak of scrub typhus in Palau occurred in 2001 to 2003 among residents of the remote southwest islands. To determine the extent of scrub typhus distribution in Palau, we tested serum samples from humans and rodents for antibodies to O. tsutsugamushi. Of 212 Palau residents surveyed in 2003, 101 (47.6%) had immunoglobulin G (IgG) antibody titers >1:64, and 56 (26.4%) had concurrent IgG and IgM antibody titers >1:512 and 1:64, respectively. Of 635 banked serum samples collected from Palau residents in 1995, 34 (5.4%) had IgG antibody titers >1:64. Sera collected from rodents (Rattus norvegicus and R. rattus) in 2003 and 2005 were tested, and 18 (28.6%) of 63 had IgG antibody titers >1:64. These findings suggest that scrub typhus is endemic in Palau.

Surveillance data from 350 U.S. outbreaks of Escherichia coli O157:H7 are analyzed.

Escherichia coli O157:H7 causes 73,000 illnesses in the United States annually. We reviewed E. coli O157 outbreaks reported to Centers for Disease Control and Prevention (CDC) to better understand the epidemiology of E. coli O157. E. coli O157 outbreaks (≥2 cases of E. coli O157 infection with a common epidemiologic exposure) reported to CDC from 1982 to 2002 were reviewed. In that period, 49 states reported 350 outbreaks, representing 8,598 cases, 1,493 (17%) hospitalizations, 354 (4%) hemolytic uremic syndrome cases, and 40 (0.5%) deaths. Transmission route for 183 (52%) was foodborne, 74 (21%) unknown, 50 (14%) person-to-person, 31 (9%) waterborne, 11 (3%) animal contact, and 1 (0.3%) laboratory-related. The food vehicle for 75 (41%) foodborne outbreaks was ground beef, and for 38 (21%) outbreaks, produce.

Salmonella enterica serotype Enteritidis emerged as an important illness during the 1980s. Investigations showed that consumption of undercooked eggs was the major risk factor for disease, and a variety of prevention and control efforts were initiated during the 1990s. We describe sporadic infections and outbreaks of S. Enteritidis in the United States from 1985 through 1999 and discuss prevention and control efforts. After reaching a high of 3.9 per 100,000 population in 1995, S. Enteritidis infections declined to 1.98 per 100,000 in 1999. While the total number of outbreaks decreased by half, those in the western states tripled. Outbreaks of S. Enteritidis phage type 4 infections accounted for 49% of outbreaks in 1999. Outbreak-associated deaths in health facilities decreased from 14 in 1987 to 0 in 1999. Overall, rates of sporadic S. Enteritidis infection, outbreaks, and deaths have declined dramatically. For further reductions, control measures should continue to be applied along the entire farm-to-table continuum.

On November 20, 2001, inhalational anthrax was confirmed in an elderly woman from rural Connecticut. To determine her exposure source, we conducted an extensive epidemiologic, environmental, and laboratory investigation. Molecular subtyping showed that her isolate was indistinguishable from isolates associated with intentionally contaminated letters. No samples from her home or community yielded Bacillus anthracis, and she received no first-class letters from facilities known to have processed intentionally contaminated letters. Environmental sampling in the regional Connecticut postal facility yielded B. anthracis spores from 4 (31%) of 13 sorting machines. One extensively contaminated machine primarily processes bulk mail. A second machine that does final sorting of bulk mail for her zip code yielded B. anthracis on the column of bins for her carrier route. The evidence suggests she was exposed through a cross-contaminated bulk mail letter. Such cross-contamination of letters and postal facilities has implications for managing the response to future B. anthracis–contaminated mailings.

The U.S. food supply is characterized increasingly by centralized production and wide distribution of products, and more foodborne disease outbreaks are dispersed over broad geographic areas. Such outbreaks may present as a gradual, diffuse, and initially unapparent increase in sporadic cases. Recognition and reporting by clinicians and local public health officials and the ordering of laboratory tests by clinicians continue to be cornerstones of detecting all outbreaks. New methods--such as active laboratory-based surveillance, automated algorithms for detecting increases in infection rates, and molecular subtyping--facilitate detection of diffuse outbreaks. Routines have evolved for the investigation of multistate outbreaks; they are characterized by rapid communication between local, state, and federal public health officials; timely review of epidemiologic data by expert panels; collaboration on tracebacks with food safety regulatory agencies; and communication with the public and media. Rapid, efficient investigation of multistate outbreaks may result in control of acute public health emergencies, identification and correction of hazardous food production and processing practices, and consequent improvement in food safety.

After inhalational anthrax was diagnosed in a Connecticut woman on November 20, 2001, postexposure prophylaxis was recommended for postal workers at the regional mail facility serving the patient’s area. Although environmental testing at the facility yielded negative results, subsequent testing confirmed the presence of Bacillus anthracis. We distributed questionnaires to 100 randomly selected postal workers within 20 days of initial prophylaxis. Ninety-four workers obtained antibiotics, 68 of whom started postexposure prophylaxis and 21 discontinued. Postal workers who stopped or never started taking prophylaxis cited as reasons disbelief regarding anthrax exposure, problems with adverse events, and initial reports of negative cultures. Postal workers with adverse events reported predominant symptoms of gastrointestinal distress and headache. The influence of these concerns on adherence suggests that communication about risks of acquiring anthrax, education about adverse events, and careful management of adverse events are essential elements in increasing adherence.

On November 11, 2001, following the bioterrorism-related anthrax attacks, the U.S. Postal Service collected samples at the Southern Connecticut Processing and Distribution Center; all samples were negative for Bacillus anthracis. After a patient in Connecticut died from inhalational anthrax on November 19, the center was sampled again on November 21 and 25 by using dry and wet swabs. All samples were again negative for B. anthracis. On November 28, guided by information from epidemiologic investigation, we sampled the site extensively with wet wipes and surface vacuum sock samples (using HEPA vacuum). Of 212 samples, 6 (3%) were positive, including one from a highly contaminated sorter. Subsequently B. anthracis was also detected in mail-sorting bins used for the patient’s carrier route. These results suggest cross-contaminated mail as a possible source of anthrax for the inhalational anthrax patient in Connecticut. In future such investigations, extensive sampling guided by epidemiologic data is imperative.

In October 1998, the Centers for Disease Control and Prevention (CDC) assisted in an investigation of an outbreak of campylobacteriosis at a school in Salina, Kansas. Twenty-two isolates were submitted from the Kansas state public health laboratory to CDC, 9 associated with the outbreak and 13 epidemiologically unrelated sporadic isolates. Pulsed-field gel electrophoresis (PFGE) using SmaI and SalI was initially used to validate the epidemiologic data. We then tested the ability of other subtyping techniques to distinguish the outbreak-associated isolates from unrelated sporadic isolates. The methods employed were somatic O serotyping, PCR-restriction fragment length polymorphism (RFLP) analysis of flaA, DNA sequence analysis of 582 bp of flaA that included the short variable region (SVR), and sequencing of the entire flaA gene. PFGE was the most discriminatory technique, yielding 11 SmaI and 10 SalI restriction profiles. All outbreak isolates were indistinguishable by PFGE, somatic O serotyping, and sequencing of the 582-bp region of the flaA gene. fla typing by PCR-RFLP grouped one sporadic isolate with the outbreak strain. Analysis of the DNA sequence of a 582-bp segment of flaA produced strain groupings similar to that generated by PCR-RFLP but further differentiated two flaA PCR-RFLP types (with a 1-bp difference in the 582-bp region). Two sporadic strains were distinct by flaA PCR-RFLP but differed only by a single base substitution in the 582-bp region. The entire flaA gene was sequenced from strains differing by a single base pair in the 582-bp region, and the data revealed that additional discrimination may in some cases be obtained by sequencing outside the SVR. PFGE was superior to all other typing methods tested for strain discrimination; it was crucial for understanding the Kansas outbreak and, when SmaI was used, provided adequate discrimination between unrelated isolates.

We evaluated the Meridian IC-STAT direct fecal and broth culture antigen detection methods with samples from children infected with Escherichia coli O157:H7 and correlated the antigen detection results with the culture results. Stools of 16 children who had recently had stool cultures positive for this pathogen (population A) and 102 children with diarrhea of unknown cause (population B) were tested with the IC-STAT device (direct testing). Fecal broth cultures were also tested with this device (broth testing). The results were correlated to a standard of the combined yield from direct culture of stools on sorbitol-MacConkey (SMAC) agar and culture of broth on SMAC agar. Eleven (69%) of the population A stool specimens yielded E. coli O157:H7 when plated directly on SMAC agar. Two more specimens yielded this pathogen when the broth culture was similarly plated. Of these 13 stool specimens, 8 and 13 were positive by direct and broth testing (respective sensitivities, 62 and 100%). Compared to the sensitivity of a simultaneously performed SMAC agar culture, the sensitivity of direct testing was 73%. Three (3%) of the population B stool specimens contained E. coli O157:H7 on SMAC agar culture; one and three of these stool specimens were positive by direct and broth testing, respectively. The direct and broth IC-STAT tests were 100% specific with samples from children from population B. Direct IC-STAT testing of stools is rapid, easily performed, and specific but is insufficiently sensitive to exclude the possibility of infection with E. coli O157:H7. Performing the IC-STAT test with a broth culture increases its sensitivity. However, attempts to recover E. coli O157:H7 by culture should not be abandoned but, rather, should be increased when the IC-STAT test result is positive.

Background

In May 2008, PulseNet detected a multistate outbreak of Salmonella enterica serotype Saintpaul infections. Initial investigations identified an epidemiologic association between illness and consumption of raw tomatoes, yet cases continued. In mid-June, we investigated two clusters of outbreak strain infections in Texas among patrons of Restaurant A and two establishments of Restaurant Chain B to determine the outbreak's source.

Methodology/Principal Findings

We conducted independent case-control studies of Restaurant A and B patrons. Patients were matched to well controls by meal date. We conducted restaurant environmental investigations and traced the origin of implicated products. Forty-seven case-patients and 40 controls were enrolled in the Restaurant A study. Thirty case-patients and 31 controls were enrolled in the Restaurant Chain B study. In both studies, illness was independently associated with only one menu item, fresh salsa (Restaurant A: matched odds ratio [mOR], 37; 95% confidence interval [CI], 7.2–386; Restaurant B: mOR, 13; 95% CI 1.3–infinity). The only ingredient in common between the two salsas was raw jalapeño peppers. Cultures of jalapeño peppers collected from an importer that supplied Restaurant Chain B and serrano peppers and irrigation water from a Mexican farm that supplied that importer with jalapeño and serrano peppers grew the outbreak strain.

Conclusions/Significance

Jalapeño peppers, contaminated before arrival at the restaurants and served in uncooked fresh salsas, were the source of these infections. Our investigations, critical in understanding the broader multistate outbreak, exemplify an effective approach to investigating large foodborne outbreaks. Additional measures are needed to reduce produce contamination.

In October 2001, the first inhalational anthrax case in the United States since 1976 was identified in a media company worker in Florida. A national investigation was initiated to identify additional cases and determine possible exposures to Bacillus anthracis. Surveillance was enhanced through health-care facilities, laboratories, and other means to identify cases, which were defined as clinically compatible illness with laboratory-confirmed B. anthracis infection. From October 4 to November 20, 2001, 22 cases of anthrax (11 inhalational, 11 cutaneous) were identified; 5 of the inhalational cases were fatal. Twenty (91%) case-patients were either mail handlers or were exposed to worksites where contaminated mail was processed or received. B. anthracis isolates from four powder-containing envelopes, 17 specimens from patients, and 106 environmental samples were indistinguishable by molecular subtyping. Illness and death occurred not only at targeted worksites, but also along the path of mail and in other settings. Continued vigilance for cases is needed among health-care providers and members of the public health and law enforcement communities.