Seroepidemiology and role of polymerase chain reaction to detect viremia in an epidemic of hepatitis E in Western India.

AIM: In an outbreak of hepatitis E affecting 859 individuals, we evaluated the titres of serological markers (IgM anti-HEV and IgG anti-HEV) and hepatitis E virus (HEV) RNA by reverse transcriptase polymerase chain reaction.
METHODS: Serological markers for acute hepatitis were evaluated in 294 icteric patients (Group A) and 300 apparently healthy controls (Group B). HEV RNA was measured by RT nPCR in 19 patients in the first week of illness in patients with negative IgM anti-HEV.
FINDINGS: None of the patients were positive for hepatitis A or B. In Group A, IgM anti-HEV was positive in 80.2%, 71.4% and 26.8% and IgG anti-HEV was positive in 58.3%, 77.1% and 86% of patients who were in their first, second and third weeks of illness, respectively. In Group A, amongst the 19 IgM anti-HEV negative patients in their first week of illness, 16 were positive for HEV RNA. In Group B 63.6% cases were positive for IgM anti-HEV. In the same village there had been a similar epidemic 4 years ago; none of the 93 patients traced from that time developed acute hepatitis during the present epidemic and all demonstrated the presence of IgG anti-HEV. This suggests that IgG anti-HEV was perhaps protective.
CONCLUSION: During the first week of illness patients may display HEV viremia while testing negative for IgM and IgG anti-HEV. The presence of IgG anti-HEV may play a protective role against HEV infection and in the absence of IgM may help in diagnosing acute hepatitis E. Over 3 weeks of illness the IgM anti-HEV titres fall progressively whilst IgG anti-HEV titres gradually rise.