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Eastern Equine Encephalitis Virus Is Found To Overwinter In The Northeastern United States

Eastern Equine Encephalitis (EEE) is a mosquito-borne viral disease affects horses throughout New Jersey, a state with abundant forested swamp habitats where the main mosquito vector (Culiseta melanura) resides. Human cases of EEE occur seasonally throughout the summer and correlate geographically with equine cases.  In addition to horses other animals such as alpaca, wild cervids, dogs and birds have been diagnosed with EEE. Viral RNA has been detected in a number of reptiles and amphibians.

Recently, the EEE virus has been found to overwinter northerly along the Eastern seaboard.  This development in the disease ecology will likely extend the local high risk season.  Researchers hypothesize that the overwintering phenomenon in the Northeast United States is due largely to changes in climatic variables that increase the viability of the mosquito host.

Due to the new ecological trends in the epidemiology of EEE, the American Association of Equine Practitioners recommends that the EEE virus vaccine be included as part the core vaccination plan for all horses.  Annual vaccination is particularly important for horses residing in areas like New Jersey, where the disease is endemic, and the climate favors increasing disease prevalence. 

If a case of EEE or West Nile (WN) is suspected in a neurologic horse, NJ AHDL will perform the following tests without an associated testing fee.  Please refer to the 2013 NJ AHDL tests offered for more information about sample type and packaging instructions.  Remember to include the Neurologic Disease Worksheet> with sample submissions from a neurologic animal.

  • EEE virus IgM ELISA
  • EEE virus PCR
  • WN virus IgM ELISA
  • WN virus PCR