Familial clustering of hepatitis B infections in gorillas

Two families of gorillas, comprising 13 animals, were studied in 1980-1982 for hepatitis virus infections. It was found that 27% of them had evidence of hepatitis B infection, and 23% evidence of hepatitis A infection. The four parents had been born in the wild and all of them had been infected with hepatitis B. The two patriarchs were positive for hepatitis B surface antigen (HBsAg) and one had hepatitis Be antigen (HBeAg). The two matriarchs had antibody to hepatitis B surface antigen. Three of the four parents had antibody to hepatitis A virus. The two gorillas with HBsAg were retested two years later and shown to be chronic carriers of HBsAg, subtype adw. Both were HBeAg positive at this time. Six of the nine children in the first generation born in captivity had antibody to hepatitis B, but none of them had antibody to hepatitis A. Two gorillas were documented by seroconversion to become infected with hepatitis B, indicating gorilla-to-gorilla transmission. During the course of this study, a recently employed keeper who had the most direct contact with the gorillas experienced an asymptomatic seroconversion to hepatitis B. This study indicates that hepatitis B in gorilla families in captivity may be a model of its behavior in human families, and that close, continuing contact with gorillas may be an occasional source of human infection.