An outbreak of fulminant hepatitis delta in the Waorani, an indigenous people of the Amazon basin of Ecuador

An outbreak of delta hepatitis occurred during 1998 among the Waorani of th e Amazon basin of Ecuador. Among 58 people identified with jaundice, 79% li ved in four of 22 Waorani communities. Serum hepatitis B surface antigen (H BsAg) was found in the sera of 54% of the jaundiced persons, and 14% of asy mptomatic persons. Ninety-five percent of 105 asymptomatic Waorani had hepa titis B core (HBc) IgG antibody, versus 98% of 51 with jaundice. These data confirm I:hat hepatitis B virus (HBV) infection is highly endemic among th e Waorani. Sixteen of 23 (70%) HBsAg carriers identified at the onset of th e epidemic had serologic markers for hepatitis D virus (HDV) infection. All 16 were jaundiced, where as only two of seven (29%) with negative HDV sero logy were jaundiced (P = .0006). The delta cases clustered in families, 69% were children and most involved superinfection of people chronically infec ted with HBV. The data suggest that HDV spread rapidly by a horizontal mode of transmission other than by the sexual route.