EPIDEMIC HEPATITIS-E IN PAKISTAN - PATTERNS OF SEROLOGIC RESPONSE AND EVIDENCE THAT ANTIBODY TO HEPATITIS-E VIRUS PROTECTS AGAINST DISEASE

IgM and IgG anti-hepatitis E virus (HEV) patterns were determined in sera collected during a hepatitis outbreak in Pakistan. HEV infection was detected serologically in 122 patients. IgM anti-HEV was detected in specimens collected up to 2 weeks before and 5-7 weeks after hospitalization in 91% and 100%, respectively, of 122 HEV-infected patients. IgG followed a similar pattern. Peak antibody titers appeared 2-4 weeks after hospitalization. At 20 months after hospitalization, IgM anti-HEV was not detected in any of 33 patients; IgG was found in all. Ige anti-HEV appeared to be protective in contacts of patients. This study confirms HEV as the cause of the outbreak, quantifies IgM and IgG anti-HEV responses, provides evidence that Ige anti-HEV protects against hepatitis E, and demonstrates that Ige anti-HEV persists, but at diminished titer, after infection. Hepatitis E in young adults is the result of primary infection with HEV and, if reinfection occurs, it does not commonly cause serious illness.