A serological study of intrafamilial spread from patients with sporadic hepatitis E virus infection.

Intrafamilial transmission is rare in epidemic hepatitis E; its frequency in sporadic hepatitis E is not known. We followed up 86 household contacts (age range 4-75 years, mean +/- SD 32.4 +/- 15.8; 49 males), who were family members of patients with acute sporadic hepatitis E. Of the 86 contacts, 68 (79%) tested negative for IgG anti-hepatitis E virus antibodies. Four (4.7%) had IgM anti-hepatitis E virus antibodies at the time of diagnosis of hepatitis E in the index case; two of these contacts possibly had hepatitis E virus infection acquired simultaneously with that in the index case, and two could have had intrafamilial transmission. None developed serological evidence of hepatitis E virus infection over a period of 49 +/- 18 days after the diagnosis of index case, although a majority lacked IgG antibodies to hepatitis E virus and were likely to be susceptible. This suggests that person-to-person transmission is uncommon in sporadic hepatitis E.