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[The duration of preservation of anamnestic antibodies to hepatitis E virus.]

The purpose of the study was to determine the duration of antibody response against hepatitis E virus (anti-HEV). Veterans of the war in Afghanistan who were in this endemic region in the late 1970s and early 1980s were tested for anti-HEV. On average, 20 years after the end of military service in Afghanistan, the rate of seropositivity was 30.0% (95/317), which was significantly higher compared to positivity rates in males who were at military service in the territory of Russia during the same period (3.9%, 8/208). At an average of 29.5 years after the visit to Afghanistan anti-HEV prevalence in veterans dropped to 20.0% (21/105), but still significantly exceeded the seroprevalence in general population (3.8%). Serum samples from elderly individuals (>60 years) without known risk factors of infection were also tested for anti-HEV IgG and IgM (n = 896). Anti-HEV IgG detection rates in the elderly from two regions of Russia exceeded those observed of primary blood donors (18.0-27.8% vs. 4.5-10.0%, p<0.01). The detection of anti-HEV IgM in individuals above 60 years (2.7-6.9%) indicates a current or recent infection. Thus, anti-HEV IgG can persist several decades after the infection. This might account for the wide anti-HEV prevalence among the elderly. At the same time, a significant proportion of individuals exposed to HEV lose detectable anti-HEV IgG within 20-30 years. The detection of anti-HEV IgM among the elderly indicates the viral circulation in older age groups, suggesting the need for testing for hepatitis E markers in elderly patients with liver diseases.