摘要Objective:To report high co-positivity of anti-dengue virus(DV) and anti-Japanese encephalitis virus(JEV)IgM in an area endemic for both the viruses and to discuss the possibilities of co-infection.Methods:Serum samples from the patients who presented with fever, suspected central nervous system infection and thrombocytopenia, were tested for anti-DVIgM and anti-JEVIgM antibodies.Conventional reverse transcriptase polymerase chain reaction was done for detection ofDVRNA andJEVRNA.Results:Of1410 patient sera tested for anti-DV and anti-JEV antibodies,129(9.14%) were co-positive for both.This co-positivity was observed only in those months when anti-JEVIgM positivity was high.Titers of both anti-DVIgM and anti-JEV IgM were high in most of the co-positive cases.Among these129 co-positive cases,76 were tested by conventional reverse transcriptase polymerase chain reaction for both flaviviruses, of which eight cases were co-positive forDV andJEV.Conclusions:Co-infection with more than one flavivirus species can occur in hyperendemic areas.