Protective role of humoral immune responses during an outbreak of hepatitis E in Egypt

Although the seroprevalence of hepatitis E virus (HEV) is approximately 80% in adult Egyptians living in rural areas, symptomatic HEV-caused acute viral hepatitis (AVH) is sporadic and relatively uncommon. To investigate the dichotomy between HEV infection and clinical AVH, HEV-specific immune responses in patients with symptomatic and asymptomatic HEV infection during a waterborne outbreak in Egypt were examined. Of 235 acute hepatitis patients in Assiut hospitals screened for HEV infection, 42(17.9%) were acute hepatitis patients confirmed as HEV-caused AVH; 37(88%) of the 42 patients were residents of rural areas, and 14(33%) were from one village (Kom El-Mansoura). Another 200 contacts of AVH cases in this village were screened for HEV and 14(7.0%), all of whom were family members of AVH cases, were asymptomatic HEV IgM-positive. HEV infections in this village peaked during the summer. Asymptomatic HEV seroconverters had significantly higher levels of epitope-specific neutralising (p=0.006) and high avidity (p=0.04)anti-HEV antibodies than the corresponding AVH cases. In conclusion, naturally acquired Immoral immune responses appear to protect HEV-exposed subjects from AVH during an HEV outbreak in Egypt. (c) 2012 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.