Sera from 360 ciconiform and pelecaniform birds collected in Florida (USA) from 1974 to 1990 were tested for serum neutralizing (SN) antibodies to eastern equine encephalitis (EEE), St. Louis encephalitis (SLE), and Everglades (EVE) viruses. Serum neutralizing antibodies to EEE virus were detected in 2%, to SLE virus in 7%, and to EVE virus in none of the samples. Pelecaniform birds (16%) had a higher antibody prevalence (P < 0.02) for SLE virus than did ciconiform birds (5%). Virus could not be isolated from 67 samples. Nestling birds with SN antibodies to both EEE and SLE viruses were found in both fresh water and marine colonies. Antibodies were more prevalent in adult and fledged juvenile birds than in nestlings.

A technique is described using a hemagglutinin formed in duck embryo cell culture under agar for rapid identification of western equine encephalomyelitis (WEE) virus by a modification of the microtiter hemagglutination inhibition test. Using this technique, 695 WEE virus strains isolated from mosquitoes and vertebrate blood samples were identified. The technique is simple, inexpensive, and rapid, allowing identification to be made within 48 h or less after initial inoculation of field specimens. Results were invariably confirmed by the plaque reduction neutralization test. The technique also appears to be applicable to the identification of eastern equine encephalomyelitis (EEE) and Venezuelan equine encephalomyelitis (VEE) viruses.