CONTAGIOUSNESS OF ACUTE HEPATITIS B - SECONDARY ATTACK RATES IN HOUSEHOLD CONTACTS

Abstract

In order to define the hazard of household exposure to patients with acute hepatitis B in the absence of persistent hepatitis B surface antigen (HBsAg), 98 household contacts of 42 patients with the acute disease were interviewed and tested for HBsAg, antibody to HBsAg (anti-HBs) and serum transaminases shortly after identification and at 3-mo. intervals for at least 12 mo. Most index cases with acute hepatitis B were young men; many used illicit drugs parenterally before the onset of illness. Three of the household contacts had HBsAg detected on initial testing, and 2 of these were carriers with elevated serum transaminase levels. The 3rd HBsAg-positive contact developed acute hepatitis within 2 wk. This appeared to represent a coprimary infection. Fourteen contacts had anti-HBs on initial evaluation and were considered immune as a result of prior experience with hepatitis B. Of 81 susceptible contacts (neither HBsAg nor anti-HBs on initial screening), 13 were spouses or sexual partners and 2 of these developed acute hepatitis B at 4 and 6 mo. after the onset of illness in their respective index cases; another developed anti-HBs at 6 mo. Thus, 3 (23%) of 13 exposed spouses or sexual partners developed evidence of hepatitis B infection during the surveillance period. No evidence of hepatitis B infection related to household exposure was found in 68 parents, siblings and other domestic contacts. These data confirm the contagiousness of hepatitis B for household contacts of acute cases and suggest that the risk is confined to spouses and sexual partners. These persons appear to be prime candidates for prophylaxis with hepatitis B immune globulin.