ABSTRACTS: Oral Presentation Abstracts
Introduction: The natural course of clinical and immunological events in symptomatic childhood HEV infection is not well characterized. The objective was to ascertain the clinical, biochemical and immunological events in children with acute symptomatic HEV infection.
Methods: Children aged 6 months–18 years with features of acute viral hepatitis were screened by ELISA for HBsAg, HBcIgM, HAV IgM and HCV antibodies. ELISA for antiHEV IgM and antiHEV IgG antibodies against Ecoli expressed ORF1, 2 and 3 was also done. Serum HEVRNA by Nested PCR technique was used for detection of viremia. Children with anti HEVIgM antibody against all three pORF’s and/or HEVRNA positivity were grouped as Isolated acute HEV (group I) and those with additional antiHAV antibodies were grouped as Mixed HEV+HAV infection (group II), and both were followed up for 2 years for their clinical, biochemical and immunological parameters. All sequential samples were tested for HEV RNA, and antiHEV IgM and IgG antibodies against all ORFs.
Results: Of 320 children screened; there were 36 with isolated and 80 had mixed HAV and HEV infections, their median ages were 45 and 67.5 months respectively. There were 6 (11.7%) and 5 (9.8%) children who had acute liver failure, of these 3 and 1died respectively in group I and II. Those who recovered completely (29 and 76 respectively), the median duration of illness from onset of illness to recovery was 45.5 (95%CI26.5–59.4) and 43 (95%CI30–51.4) days respectively. At contact, in group I 14 (38.8%) children were antiHEV IgM positive alone, 9 (25%) were positive for HEVRNA and antiHEV IgM, and 13 (36.1%) were only HEVRNA positive without HEV IgM antibodies. In group II 65% (32/49) were antiHEV IgM positive but no RNA was detected and 34.6% (17/49) were positive for both. There were 13 (36%) and 30 (37.5%) children in group I and II respectively, who showed rise in sequential antiHEV IgM antibodies after they had become negative for a period of more than 6 months, and 8 (18.6%) children also had raised ALT/AST levels. Re-appearance of HEVRNA after it became negative was seen in 84.6% (11/13) and 60% (18/30) of these children in group I and II respectively after a long period of RNA negativity. Sequencing of 2 pairs of sera of two patients, in whom there was re-appearance of HEV RNA, revealed genetic divergence of 1.7% and homology of 94.5% between them.
Conclusion: The data shows that the immune response to HEV infection in children is different from adults. There was evidence of re-appearance of HEV RNA along with anti HEV IgM antibodies, suggesting re-infection, in 84.6% and 60% children in groups I and II respectively.