EASTERN EQUINE ENCEPHALOMYELITIS VIRUS IN RELATION TO THE AVIAN COMMUNITY OF A COASTAL CEDAR SWAMP

Eastern equine encephalomyelitis virus (EEEV) is perpetuated in easter n North America in a mosquito-wild bird maintenance cycle that involve s Culiseta melanura (Coquillett) as the principal enzootic vector and passerine birds as the primary amplifying hosts. We examined the role of birds in the EEEV cycle at a site in southern New Jersey where EEEV cycles annually at high levels. Birds and mosquitoes were sampled dur ing three epiornitics and one season of limited virus activity. We exa mined antibody prevalence in birds in relation to eight physical and n atural history characteristics. Our goal was to compare EEEV cycling i n C. melanura and the primary avian hosts better to understand the mec hanisms that initiate annual epiornitics. Antibody prevalence was high est in the Blue Jay (62%), Wood Thrush (60%), and Tufted Titmouse (44% ). Resident status of birds was the natural history characteristic mos t closely linked to participation in the EEEV cycle. Species spending the greatest amount of time at our study site (permanent residents, su mmer residents) had the highest antibody rates. We captured viremic bi rds as early as 25 May, 51 d before we first detected virus in C. mela nura. We recaptured 10 after hatching year adults and one hatching yea r (HY) bird that seroconverted before we detected virus in C. melanura . We also found EEEV antibody in 15 HY birds up to 31 d before we isol ated EEEV from C. melanura. We provide evidence that a cryptic cycle d evelops weeks before epiornitic cycling is detected in C. melanura by traditional laboratory techniques, indicating that the early season cy cle is initiated by the recrudescence of latent virus in previously in fected birds.