Association of hepatitis E virus with an outbreak of hepatitis at a military training camp in Nepal

Abstract

From 29 January 1995 to 15 March 1995, an outbreak of hepatitis occurred among 692 soldiers at an isolated training camp 25 km east of Kathmandu. Thirty-two cases occurred approximately 8 weeks after arrival of soldiers at the camp. To determine the etiology of the outbreak, patient sera were examined for evidence of infection with hepatitis A, B, C, and E viruses using commercially available enzyme-linked immunosorbent assay (ELISA) kits. The polymerase chain reaction (PCR) was used to detect hepatitis E virus (HEV) RNA. Evidence of recent infection (IgM to HEV and/or HEV RNA) was found in all but two patients, whereas none had evidence of recent infection with hepatitis A, B, or C viruses. Therefore, the outbreak was attributed to HEV. Fecally contaminated drinking water was suspected as the source of the outbreak. To determine the extent of HEV infections among those without clinical hepatitis, sera from the remaining soldiers were examined for markers of HEV infection. Evidence of past infection (IgG to HEV in the absence of IgM or HEV RNA) was found among 204 soldiers (prevalence = 30%), leaving 488 individuals susceptible to infection at the onset of the outbreak. Evidence of recent infection was found among another 83 individuals. We conclude that most exposed, susceptible soldiers sustained HEV infection without experiencing overt hepatitis. If the levels of virus inoculum and prior immunity in this population were typical, inapparent infection may be the usual adult response to virus exposure in an endemic area.

Epidemic of hepatitis E in a military unit in Abbotrabad, Pakistan.

“…Among contacts, the subclinical to clinical ratio was 4:1. This ratio is higher than those reported from an outbreak of hepatitis E in Nepalese soldiers in which subclinical infection occurred 2.8 times as often as clinical hepatitis 11 or when compared with subclinical rates which were twice as high as disease rates in military and police personnel in Nepal. 34 This may have resulted from the small number (10) of persons observed or that the diagnostic assay used in the Nepalese studies was less sensitive than the assay used in the present study.…”

“…The combined prevalence in contacts and controls (28%) is similar to that observed for IgG (without IgM) in Nepalese soldiers in an outbreak situation (30%). 11 Cross-sectional studies in Nepal and India indicate that the prevalence of anti-HEV increases with age. 34,35 In both studies, the prevalence increased from 16% in young adolescents to 31% in those more than 40 years old.…”

“…In addition to civilian cases, hepatitis E outbreaks have been documented in military populations in Chad, 9 Djibouti, 10 Nepal, 11 Ethiopia, 12 and among Bangladeshi soldiers serving with the United Nations Forces in Haiti. 13 French and Italian soldiers, but apparently not American or Belgian Forces serving in Somalia, 14 have also been infected.…”

The socioeconomic impact of hepatitis E in Nepal.

“…12 Hepatitis E disease outbreaks have also been reported among the militaries of Nepal and Ethiopia. 13 Prevention and control efforts directed against this geographically widespread problem have the potential to prevent significant morbidity, substantial expenditures for health care, and lost wages in countries other than Nepal. Total costs to the individual with HE would be expected to exceed those reported for this population in higher income brackets also at risk for HE.…”

Microbiological Safety of Drinking Water: United States and Global Perspectives

“…These authors feel that on the basis of its epidemiology, HAV is one of the most prevalent waterborne viral pathogens. Rotaviruses are also frequently reported in outbreaks (Table 4) and, together with enteroviruses, have been isolated from chlorinated drinking water systems (149,150 (155), and Nepal (156). Mortality can be high, particularly among pregnant women, i.e, estimated to be 13.8% in the Somalia outbreak.…”