JAPANESE ENCEPHALITIS IN SRI-LANKA - COMPARISON OF VECTOR AND VIRUS ECOLOGY IN DIFFERENT AGROCLIMATIC AREAS

The ecology of Japanese encephalitis (JE) in different agro-climatolog ical areas of Sri Lanka was studied in relation to the abundance of mo squito vectors, infection in domestic livestock, and human infection a nd disease. There was an inverse correlation between altitude and the abundance of potential JE vectors, as well as JE seroprevalence in dom estic livestock and in man. Little or no JE infection was documented a bove 1200 m elevation. JE seroprevalences in cattle and goats were bet ter predictors of human infection risk than was porcine seroprevalence . In areas with asynchronous porcine infection occurring over many mon ths, high overall JE seroprevalence in pigs was found with little evid ence of human infection. Porcine JE infection occurring in synchronous bursts associated with monsoonal rains was correlated with significan t bovine, ovine and human seroprevalence in 2 low elevation study area s, Anuradhapura (dry zone) and Ragama (wet zone), with epidemic human JE in the former area and endemic disease in the latter.