Use of immunoglobulin M antibody capture enzyme-linked immunosorbent assay in the surveillance of Rocio encephalitis

ABSTRACT

In 1975-1976 an extensive epidemic of Rocio encephalitis occurred in the South region of the Sao Paulo State, Brazil. Since June 1976 no serological confirmation of this diagnosis has been made. Sera from 90 patients clinically suspected of having contracted Rocio encephalitis between July 1976 and December 1982, were tested with an immunoglobulin M (IgM) antibody capture enzyme immunoassay (MAC ELISA). Only one serum sample was available for each of these patients. Four presumptive cases of Rocio encephalitis were identified. Three of these sera had been collected in August and September of 1976. The fourth one, from a boy one year of age who died from the disease, was collected in April 1980. These results indicate that Rocio virus was circulating in the human population causing severe disease, at least until 1980. MAC ELISA is useful for surveillance of Rocio encephalitis in an area where the collection of paired sera samples is very difficult.