Hepatitis E Among Refugees in Kenya: Minimal Apparent Person-to-person Transmission, Evidence for Age-dependent Disease Expression, and New Serologic Assays

In 1991, a large outbreak of hepatitis E occurred among refugees in Kenya. The overall clinical attack rate in the refugee camp was 6.3% (1702/26920). The primary attack rate in the entire refugee camp (4.8%) and the secondary attack rate in case-households (4.4%) were similar. Three recently developed tests were used for this investigation, including a synthetic peptide-based enzyme immuno-assay (EIA) to detect IgG antibody to hepatitis E virus (anti-HEV) and Western blot assays to detect IgG and IgM anti-HEV. In a sample of 132 case-patients, IgG anti-HEV was detected in 101 (77%) by peptide EIA and 96 (73%) by Western blot; the concordance between EIA and Western blot was 91%. Our findings suggest that >50% of HEV infections may have been anicteric and the expression of icterus with HEV infection was age-dependent. Moreover, in spite of poor hygienic conditions present in the refugee camp, little person-to-person transmission was apparent in households.