EVIDENCE FOR MULTIPLE FOCI OF EASTERN EQUINE ENCEPHALITIS-VIRUS (TOGAVIRIDAE, ALPHAVIRUS) IN CENTRAL NEW-YORK-STATE

A regional surveillance system for eastern equine encephalitis (EEE) v irus was established in central New York in 1984 after the 2nd human E EE fatality occurred in 1983. Extensive mosquito surveillance activiti es were coordinated with the rapid laboratory processing of mosquito s pecimens for EEE virus. Active surveillance for EEE infections in huma ns equines also was initiated. Results of long-term surveillance detec ted the presence of multiple Culiseta breeding swamps. A 6-yr inter ep izootic period (1984-1989) was followed by 2 yr of equine EEE. In 1990 , there were 7 equine cases and a record number of EEE virus isolation s from mosquitoes (n = 86), wild birds (n = 27), and sentinel pheasant s (n = 7). In 1991, 7 equine cases also occurred, although there were fewer isolations from mosquitoes (n 40). Tile sequence to the appearan ce of EEE virus at swamp and upland sites and at individual swamp comp lexes, and the spatial and temporal distribution of equine cases provi de evidence for multiple foci of EEE virus in central New York. The ro le of infected Culiseta,seta melanura (Coquillett) in the transfer of EEE virus between swamp and upland areas and among swamp complexes is advanced.