Introduction: In New York State (NYS), Eastern equine encephalitis (EEE) was first reported in a human in 1971, in horses in 1970, and in pheasants in 1952.
Material and method: Following work for the interval from 1970 to 1991, we identified cases in vertebrates from 1992 to 2012, through a passive surveillance system involving veterinarians in clinical practice, county health departments, and the Departments of Agriculture and Markets, Environmental Conservation, and Health, of the State of New York.
Result: During an 11-year hiatus, from 1992 to 2002, no case in any vertebrate was observed. In a re-emergence, from 2003 to 2012, disease occurred in 12 counties, including 7 counties where disease had never been documented. Vertebrate cases included 4 cases in humans and 77 nonhuman occurrences; in 58 horses, Equus ferus caballus L.; 2 deer, Odocoileus virginianus Zimmermann; 6 dogs, Canis familiaris; 10 birds; and 1 flock of pheasants, Phasianus colchicus L. These were the first reported cases in NYS in white-tailed deer, the domestic dog, and in five species of birds: American crow, Corvus brachyrhynchos Brehm; American goldfinch, Carduelis tristis L.; bald eagle, Haliaeetus leucocephalus L.; blue jay, Cyanocitta cristata (L.); and red-tailed hawk, Buteo jamaicensis Gmelin. One crow was dually infected with EEE virus and West Nile virus. The northern, southern, and southeastern borders of the state were newly affected.
Conclusion: The geographic area, time periods, and vertebrate species with risk of EEE disease expanded from 1992 to 2012.
Keywords: Arthropod-borne; Bird; Deer; Dog; Eastern equine encephalitis virus; Encephalitis; Horse; Mosquito; New York State; Pheasant; Vertebrate.