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The risk of the spread of hepatitis B virus infection from deinstitutionalized, mentally retarded carriers to pupil and staff school contacts in the New York City public school system was measured serologically in a three-phase study from 1978 to 1982. In the third phase, undertaken in 1982, blood samples were drawn and questionnaires were completed on students and staff tested in either of the first two phases and on comparison groups with intermediate and no known school exposure to deinstitutionalized carriers. Univariate and logistic regression analyses revealed that staff and pupils with a history of classroom exposure to a hepatitis B virus carrier had significantly increased prevalences of hepatitis B virus infection (13.4%, odds ratio = 1.9; 9.3%, odds ratio = 2.5, respectively). Similarly, yearly seroconversion rates of 1.3% and 0.67% indicate that staff and, to a lesser extent, pupils are at increased risk of infection.

Over a 21-month interval, we investigated the effectiveness of immunoglobulin (lg) in preventing hepatitis A spread in day-care centers. Immunoglobulin was given to all center and employees whenever hepatitis occurred in one center child or employee or parents in two families. Immunoglobulin programs were completed in 91 centers during the trial within an average of 17 days of onset of illness in the index case. Immunoglobulin intervention caused significant reduction in the average size of a day-care hepatitis outbreaks, from 7.3 cases in historically untreated centers to 6.0 cases in Ig-treated centers. Cases in center children and employees virtually ceased two weeks after Ig intervention, while those in household contacts decreased significantly within six weeks. Reported cases of hepatitis type A or unspecified in the community decreased 75%, and the number of new hepatitis outbreaks decreased 77% during the trial. A decrease occurred not only in day-care-associated cases, but in cases not directly associated with centers, probably due to decreased tertiary spread from day-care families into the community. Use of Ig to prevent hepatitis spread in day-care centers seems to be an excellent means of controlling this disease, both within the centers and the general community.

To define the epidemiologic features of occupationally acquired hepatitis B infection among physicians, we conducted a seroepidemiologic survey of physicians attending three American Medical Association conventions in 1975 and 1976. Of 1,192 participating physicians, 220 (18.5%) had serologic evidence of prior hepatitis B virus infection (positive hepatitis B surface antibody). The infection rate was higher among those practicing in urban communities; it increased with the number of years in practice; and among specialties, it was highest in pathologists (27%) and surgeons (28%). The serologic data demonstrated a changing pattern of viral hepatitis related to entry into the medical profession, with hepatitis B accounting for a majority of clinical hepatitis experienced after beginning medical practice.

To determine if heterosexual activity was a risk factor for acquiring hepatitis B virus (HBV) infection, we studied attendees at a sexually transmitted disease (STD) clinic and students at a large university. Responses to self-administered questionnaires were used to exclude persons with factors known to be related to the acquisition of HBV and to determine the number of recent (past four months) and lifetime sexual partners. Serum samples were tested for hepatitis B surface antigen, antibody to hepatitis B surface antigen, and antibody to hepatitis B core antigen. For white heterosexuals in the STD group, the prevalence of HBV infection was 6% for those with fewer than five recent partners vs 21% for those with five or more partners, and 5% for those with fewer than 50 lifetime partners vs 20% for those with 50 or more partners. For black heterosexuals in the STD group, no association was found between prevalence of HBV infection and number of recent or lifetime sexual partners. For the heterosexual student group (all white), the prevalence of HBV infection was 1.5% for fewer than three recent partners vs 14% for three or more partners, and 2% for fewer than ten lifetime partners vs 7% for ten or more partners. For white heterosexuals, the risk of acquiring HBV infection increases with increasing amounts of sexual activity and may reach a level similar to that of other groups previously recognized to be at high risk of acquiring hepatitis B.

Six cases of hepatitis B-associated vasculitis occurred during a four-year period in Eskimos living in southwest Alaska, an area hyperendemic for hepatitis B. All showed positive results in tests for hepatitis B surface antigen (HBsAg), and all five patients tested for hepatitis B e antigen (HBeAg) showed positive values. Two patients died of the disease. Of three who recovered, two had positive values for HBsAg and HBeAg when tested two years later. In the villages of four patients, the prevalence of hepatitis B virus (HBV) infection ranged from 18.2% to 73.1%. Serological evidence of HBsAg was found in 22% and antibody to HBsAg (anti-HBs) in 30% of close relatives of the patients. Two patients had no previous serological evidence of infection with HBV, indicating that vasculitis followed recent infection. The results provide epidemiologic evidence of the clinical association between HBV infection and vasculitis.

Between April 1, 1984, and Feb 1, 1985, nine cases of hepatitis B occurred in the patients of a dentist practicing in a rural Indiana county (population, 35,000). This was over 20 times the mean annual incidence for the county in the previous decade. All of the patients had been treated by the dentist two to five months before illness. Although the dentist had never had hepatitis symptoms, his serum was positive for hepatitis B surface antigen and hepatitis B e antigen and negative for anti-hepatitis B core IgM antibody, indicating that he was probably a hepatitis B carrier. Two patients (22%) died of fulminant hepatitis; the case-fatality ratio was over ten times the reported US mean for hepatitis B. Using a case definition based on anti-hepatitis B core IgM antibody positivity and exposure to the dentist during a defined time period, a serosurvey of the dentist's patients identified 15 asymptomatic cases (overall attack rate, 3.2%). Infection risk was related to the amount of trauma involved in the cases' dental procedures. No cause was found for the unusual lethality of the outbreak.

The Centers for Disease Control surveyed 1,255 chronic hemodialysis centers in the United States in 1983 to assess the use of hepatitis B vaccine as well as the risk of acquiring hepatitis B among both patients and staff. The response rate to a mailed questionnaire was 90%. Seventy-one percent of the centers reported that they gave vaccine, but only an estimated 6% of susceptible patients and 32% of susceptible staff received all three doses of vaccine. Centers more likely to give vaccine included those that provided dialysis to large patient populations and those that provided dialysis for hepatitis B surface antigen-positive patients. As a result of vaccine administration, the overall prevalence of antibody to hepatitis B surface antigen increased significantly, to 18% for patients and 39% for staff. Extensive use of the vaccine in the future, combined with infection control practices, could virtually eliminate the risk of acquiring hepatitis B virus infection in hemodialysis centers.