RESUMEN
A serological study was undertaken to determine the role of arboviruses as etiological agents of encephalitis in the People's Republic of China (PRC). Paired sera were collected during mosquito seasons in 1988-1990 from 614 patients with possible viral encephalitis in 15 regions of PRC and tested for haemagglutination inhibiting antibodies to selected arboviruses. Seroconversions were documented to alphavirus and flavivirus antigens in 13.0 and 18.7% of patients respectively in most of the study areas. No California group seroconversion was detected. The age of alphavirus seroconvertors ranged from 2 months to 32 years and of flavivirus seroconvertors from 6 months to 50 years, with higher numbers in males. Serious central nervous system manifestations were seen more commonly in flavivirus seroconvertors. This study affirms the importance of flavivirus as causative agents of encephalitis in PRC and provides evidence that one or more alphaviruses are causing symptomatic infections with neurological involvement in PRC.