Diagnosis of enterovirus 70 infection by demonstration of IgM antibodies

Since outbreaks of severe acute hemorrhagic conjunctivitis occur worldwide [Hierholzer and Hatch, 1985] and the majority of the epidemics are caused by enterovirus 70 (EV-70), we developed an EV-70 IgM ELISA to simplify the diagnosis of these outbreaks. The test is based on the capture antibody technique and the use of monoclonal antibodies to EV-70. We detected EV-70 IgM antibodies in 55% of 76 convalescent-phase sera from an outbreak of acute hemorrhagic conjunctivitis in a Brazilian community. Among the 71 acute- and convalescent-phase serum pairs from this outbreak, 49 (69%) demonstrated a 4-fold or greater rise in neutralizing antibody-titer. The titer of IgM antibody began to drop by the fifth week after onset of illness. EV-70 IgM antibodies were not detected in 53 serum pairs with a 4-fold or greater rise in antibodies to other picornaviruses. The EV-70 ELISA proved to simple and relatively rapid to perform, appeared to be specific, and should be sensitive enough to diagnose outbreaks of EV-70 when multiple serum specimens can be tested.