Factors associated with student participation in a school-based hepatitis B immunization program.

This study examined the relationship between participation in a school-based hepatitis B immunization program and teacher attitudes toward school-based health care and student socioeconomic factors. A survey addressing teachers' attitudes was administered to all teachers participating in the program. Information regarding student participation in school lunch programs and scores on national standardized tests were collected. Of the 4,874 fifth-grade students targeted for the program, 3,483 (72%) consented to be vaccinated and 3,232 (93% of 3,483) received all three doses of vaccine. Socioeconomic factors were the most important predictors of student participation in this school-based immunization program. Participation was significantly lower among students in schools with a high proportion of students receiving free or reduced-price school lunch and with low test scores. The only teacher factor associated with student participation was whether the teacher had returned the questionnaire. Strategies to increase immunization coverage in school-based programs should target children of low socioeconomic status.

An outbreak of hospital-acquired hepatitis B virus infection among patients receiving chronic hemodialysis.

OBJECTIVE: To investigate a cluster of hepatitis B virus (HBV) infections between December 1995 and May 1996 among chronic hemodialysis patients in one county. SETTING: Two dialysis centers (A and B) and a hospital (C) in one county. PATIENTS: Six case-patients who were dialyzed in one of two centers, A and B, and had all been hospitalized between January and February 1996 at hospital C. METHODS: Patient 1, usually dialyzed in center A, sero-converted to hepatitis B surface antigen (HBsAg) in December 1995 and could have been the source of infection for the others, who seroconverted between March and April 1996. Two cohort studies were conducted: one among patients dialyzed in center A, to determine where transmission had occurred, and one among patients dialyzed at hospital C at the time patient 1 was hospitalized, to identify factors associated with infection. RESULTS: Four (15%) of the 26 susceptible patients dialyzed at center A became infected with HBV. Hospitalization at hospital C when patient 1 was hospitalized was associated with infection (P = .002). A cohort study of the 10 susceptible patients dialyzed at hospital C during the time patient 1 was hospitalized did not identify specific risk factors for infection. However, supplies and multidose vials were shared routinely among patients, providing opportunities for transmission. CONCLUSION: When chronic hemodialysis patients require dialysis while hospitalized, their HBsAg status should be reviewed, and no instrument, supplies, or medications should be shared among them.

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.

First reported outbreak in the United States of cryptosporidiosis associated with a recreational lake.

In the summer of 1994, an outbreak of cryptosporidiosis occurred among visitors to a state park in New Jersey. We enrolled 185 persons in a cohort study, 38 (20.5%) of whom had laboratory-confirmed cryptosporidiosis or gastrointestinal illness that met our clinical case definition. Having any exposure to lake water (e.g., swimming) was strongly associated with illness (P < .001). The outbreak lasted 4 weeks and affected an estimated 2,070 persons. The most likely sources of the outbreak were contaminated runoff of rainwater and infected bathers. This outbreak of cryptosporidiosis is the first reported to be associated with recreational exposure to lake water. Our investigation shows that even a large and ongoing outbreak may not be detected for several weeks. Health professionals and persons at high risk for severe cryptosporidiosis should be aware that recreational water can be a source of cryptosporidium infection.

Cryptosporidiosis: an outbreak associated with drinking water despite state-of-the-art water treatment.

OBJECTIVE: To determine the magnitude and source of an outbreak of cryptosporidiosis among persons with human immunodeficiency virus (HIV) infection and to determine whether the outbreak extended into the immunocompetent population. DESIGN: Matched case-control study and environmental investigation. SETTING: Clark County, Nevada. PARTICIPANTS: Adults with HIV infection (36 case-patients with laboratory-confirmed Cryptosporidium parvum infection and 107 controls), matched by physician or clinic and by CD4+ cell count category. MEASUREMENTS: Potential risk factors for infection, death rates, and data on water quality. RESULTS: Review of surveillance and microbiology records identified 3 cases of cryptosporidiosis in 1992 (the first year that cryptosporidiosis was reportable in Nevada), 23 cases in 1993, and 78 cases in the first quarter of 1994. Of the 78 laboratory-confirmed cases in the first quarter of 1994, 61 (78.2%) were in HIV-infected adults. Of these 61 adults, 32 (52.5%) had died by 30 June 1994; at least 20 of the 32 (62.5%) had cryptosporidiosis listed on their death certificates. In the case-control study, persons who drank any unboiled tap water were four times more likely than persons who drank only bottled water to have had cryptosporidiosis (odds ratio, 4.22 [95% Cl, 1.22 to 14.65]; P = 0.02). For persons with CD4+ cell counts less than 100 cells/mm3, the association between tap water and cryptosporidiosis was even stronger (odds ratio, 13.52 [Cl, 1.78 to 102.92]; P = 0.01). Additional data indicate that this outbreak also affected persons who were not infected with HIV. No elevated turbidity values or coliform counts and no Cryptosporidium oocysts were found in testing of source (Lake Mead) or finished (treated) water during the study period, but so-called presumptive oocysts were intermittently found after the investigation in samples of source water, filter backwash, and finished water. CONCLUSIONS: A cryptosporidiosis outbreak was associated with municipal drinking water, despite state-of-the-art water treatment and water quality better than that required by current federal standards. This outbreak highlights the importance of surveillance for cryptosporidiosis and the need for guidelines for the prevention of water-borne-Cryptosporidium infection among HIV-infected persons.