A multistate, foodborne outbreak of hepatitis A. National Hepatitis A Investigation Team.
BACKGROUND: We investigated a large, foodborne outbreak of hepatitis A that occurred in February and March 1997 in Michigan and then extended the investigation to determine whether it was related to sporadic cases reported in other states among persons who had consumed frozen strawberries, the food suspected of causing the outbreak. METHODS: The cases of hepatitis A were serologically confirmed. Epidemiologic studies were conducted in the two states with sufficient numbers of cases, Michigan and Maine. Hepatitis A virus RNA detected in clinical specimens was sequenced to determine the relatedness of the virus from outbreak-related cases and other cases. RESULTS: A total of 213 cases of hepatitis A were reported from 23 schools in Michigan and 29 cases from 13 schools in Maine, with the median rate of attack ranging from 0.2 to 14 percent. Hepatitis A was associated with the consumption of frozen strawberries in a case-control study (odds ratio for the disease, 8.3; 95 percent confidence interval, 2.1 to 33) and a cohort study (relative risk of infection, 7.5; 95 percent confidence interval, 1.1 to 53) in Michigan and in a case-control study in Maine (odds ratio for infection, 3.4; 95 percent confidence interval, 1.0 to 14). The genetic sequences of viruses from 126 patients in Michigan and Maine were identical to one another and to those from 5 patients in Wisconsin and 7 patients in Arizona, all of whom attended schools where frozen strawberries from the same processor had been served, and to those in 2 patients from Louisiana, both of whom had consumed commercially prepared products containing frozen strawberries from the same processor. CONCLUSIONS: We describe a large outbreak of hepatitis A in Michigan that was associated with the consumption of frozen strawberries. We found apparently sporadic cases in other states that could be linked to the same source by viral genetic analysis. (+info)
Changing epidemiology of hepatitis A in the 1990s in Sydney, Australia.
Surveillance of hepatitis A in residents of Eastern Sydney Health Area identified substantial epidemics in homosexual males in 1991-2 with a peak rate of 520 per 100,000 recorded in males aged 25-29 years, and again in 1995-6, with a peak rate of 405 per 100,000 per year in males aged 30-34 years. During 1994-5 an epidemic was detected among disadvantaged youth associated with injecting drug use; peak rates of 200 per 100,000 per year were reported in males aged 25-29 years and of 64 per 100,000 per year among females aged 20-24 years. The epidemiology of hepatitis A in these inner suburbs of Sydney is characterized by very few childhood cases and recurrent epidemics among homosexual men. Identified risk groups need to be targeted with appropriate messages regarding the importance of hygiene and vaccination in preventing hepatitis A. However, poor access to health services among disadvantaged youth and a constant influx of young homosexual males into these inner suburbs present major challenges to hepatitis A control. (+info)
Prevalence of enteric hepatitis A and E viruses in the Mekong River delta region of Vietnam.
A study of antibody prevalence for hepatitis A virus (HAV) and hepatitis E virus (HEV) was carried out in southwestern Vietnam in an area adjacent to a known focus of epidemic HEV transmission. The purpose of this investigation was first to provide a prevalence measure of hepatitis infections, and second to determine the outbreak potential of HEV as a function of the susceptible population. Blood specimens collected from 646 persons in randomly selected village hamlets were examined by an ELISA for anti-HEV IgG and anti-HAV IgG. The prevalences of anti-HEV IgG and anti-HAV IgG were 9% and 97%, respectively. There was a significant increase (P < 0.01) in age-specific anti-HEV IgG. A notable increase in anti-HAV IgG prevalence (P < 0.0001) occurred between child populations 0-4 (64%) and 5-9 (95%) years of age. No evidence of familial clustering of anti-HEV IgG-positive individuals was detected, and household crowding was not associated with the spread of HEV. Boiling of water was found to be of protective value against HEV transmission. A relatively low prevalence of anti-HEV indicates considerable HEV outbreak potential, against a background of 1) poor, water-related hygiene/sanitation, 2) dependence on a (likely human/animal waste)-contaminated Mekong riverine system, and 3) periodic river flooding. (+info)
An outbreak of hepatitis A associated with an infected foodhandler.
OBJECTIVE: The recommended criteria for public notification of a hepatitis A virus (HAV)-infected foodhandler include assessment of the foodhandler's hygiene and symptoms. In October 1994, a Kentucky health department received a report of a catering company foodhandler with hepatitis A. Patrons were not offered immune globulin because the foodhandler's hygiene was assessed to be good and he denied having diarrhea. During early November, 29 cases of hepatitis A were reported among people who had attended an event catered by this company. Two local health departments and the Centers for Disease Control and Prevention, in collaboration with two state health departments, undertook an investigation to determine the extent of the outbreak, to identify the foods and event characteristics associated with illness, and to investigate the apparent failure of the criteria for determining when immune globulin (IG) should be offered to exposed members of the public. METHODS: Cases were IgM anti-HAV-positive people with onset of symptoms during October or November who had eaten foods prepared by the catering company. To determine the outbreak's extent and factors associated with illness, the authors interviewed all case patients and the infected foodhandler and collected information on menus and other event characteristics. To investigate characteristics of events associated with transmission, the authors conducted a retrospective analysis comparing the risk of illness by selected event characteristics. To evaluate what foods were associated with illness, they conducted a retrospective cohort study of attendees of four events with high attack rates. RESULTS: A total of 91 cases were identified. At least one case was reported from 21 (51%) of the 41 catered events. The overall attack rate was 7% among the 1318 people who attended these events (range 0 to 75% per event). Attending an event at which there was no on-site sink (relative risk [RR] = 2.3, 95% confidence interval [CI] 1.4, 3.8) or no on-site kitchen (RR = 1.9, 95% Cl 1.1, 2.9) was associated with illness. For three events with high attack rates, eating at least one of several uncooked foods was associated with illness, with RRs ranging from 8 to undefined. CONCLUSION: A large hepatitis A outbreak resulted from an infected foodhandler with apparent good hygiene and no reported diarrhea who prepared many uncooked foods served at catered events. Assessing hygiene and symptoms s subjective, and may be difficult to accomplish. The effectiveness of the recommended criteria for determining when IG should be provided to exposed members of the public needs to be evaluated. (+info)
Identifying target groups for a potential vaccination program during a hepatitis A communitywide outbreak.
OBJECTIVES: This study sought to identify groups for targeted vaccination during a communitywide hepatitis A outbreak in 1996. METHODS: Residents of the Sioux City, Iowa, metropolitan area reported with hepatitis A between September 1995 and August 1996 were sampled and compared with population-based controls. RESULTS: In comparison with 51 controls, the 40 case patients were more likely to inject methamphetamine, to attend emergency rooms more often than other health care facilities, and to have a family member who used the Special Supplemental Nutrition Program for Women, Infants, and Children. CONCLUSIONS: Groups at increased risk of hepatitis A can be identified that might be [corrected] accessed for vaccination during communitywide outbreaks. (+info)
The epidemiology of viral hepatitis in children in South Texas: increased prevalence of hepatitis A along the Texas-Mexico border.
An initial retrospective study of 194 children demonstrated a high prevalence of hepatitis A but not hepatitis B or C infection among children living along the Texas-Mexico border. A larger prospective study of hepatitis A was conducted with 285 children (aged 6 months to 13 years) living in 3 sociodemographically dissimilar areas of South Texas. Children living in colonias along the border had a significantly higher prevalence of hepatitis A virus infection (37%) than children living in urban border communities (17%) or in a large metropolitan area (San Antonio [6%]). Independent risk factors for hepatitis A infection included increased age, colonia residence, and history of residence in a developing country. Use of bottled water (vs. municipal or spring/well water) and years of maternal secondary education were protective. Improved sanitation or routine hepatitis A vaccination in early childhood may reduce the prevalence of hepatitis A in these areas. (+info)
Antigenic epitopes of the hepatitis A virus polyprotein.
Forty-two antigenic domains were identified across the hepatitis A virus (HAV) polyprotein by using a set of 237 overlapping 20-mer synthetic peptides spanning the entire HAV polyprotein and a panel of serum samples from acutely HAV-infected patients. The term "antigenic domain" is used in this study to define a protein region spanned with consecutive overlapping immunoreactive peptides. Nineteen antigenic domains were found within the structural proteins, and 22 were found within the nonstructural proteins, with 1 domain spanning the junction of VP1 and P2A proteins. Five of these domains were considered immunodominant, as judged by both the breadth and the strength of their immunoreactivity. One domain is located within the VP2 protein at position 57-90 aa. A second domain, located at position 767-842 aa, contains the C-terminal part of the VP1 protein and the entire P2A protein. A third domain, located at position 1403-1456 aa, comprises the C-terminal part of the P2C protein and the N-terminal half of the P3A protein. The fourth domain, located at position 1500-1519 aa, includes almost the entire P3B, and the last domain, located at position 1719-1764 aa, contains the C-terminal region of the P3C protein and the N-terminal region of the P3D protein. It is interesting to note that four of the five most immunoreactive domains are derived from small HAV proteins and/or encompass protein cleavage sites separating different HAV proteins. The HAV-specific immunoreactivity of each antigenically reactive peptide was confirmed by using seven HAV seroconversion panels. Collectively, these data demonstrate that HAV structural and nonstructural proteins contain antigenic epitopes that can be efficiently modeled with short synthetic peptides. (+info)
Ascertainment of secondary cases of hepatitis A--Kansas, 1996-1997.
Each year, 25,000-30,000 cases of hepatitis A are reported in the United States. The most common infection source (22%-26%) is household or sexual contact with a person already infected with hepatitis A virus (HAV) (i.e., the source-patient). In Kansas during 1992-1997, contact with a source-patient was reported by 39% of persons with hepatitis A. Cases reported in 1996 and 1997 were studied retrospectively to determine the reasons for the apparently high proportion of secondary cases and to evaluate missed opportunities for prevention (i.e., postexposure prophylaxis with immune globulin [IG]). Results of this investigation indicate that persons with hepatitis A often were classified incorrectly as secondary cases and that some correctly identified secondary cases represented missed opportunities for prevention. (+info)