Everglades virus

From Dog
Residence locations of Everglades virus–seropositive and –seronegative dogs in Florida and landcover habitat types obtained from the National Land Cover Database[1]

Everglades virus is an alphavirus included in the Venezuelan equine encephalitis virus (VEEV) complex.

Although normally nonpathogenic to dogs, this virus can be transmitted between dogs and humans by mosquito vectors (Culex spp & Aedes spp)[2].

In humans, this virus causes febrile disease, sometimes accompanied by neurologic manifestations[3].

Field studies in VEEV-enzootic foci outside Florida also indicate that dogs are frequently infected during outbreaks. Domestic dogs tested after epidemics in Colombia[4], Venezuela[5], and Guatemala[6] commonly had neutralizing antibody to VEEV

Surveys in the everglades of southern USA indicate a low prevalence of seropositivity (approx 5%), but sufficient to warrant concern as a zoonotic reservoir for human infections[7].

Clinical signs are usually absent but dogs presenting with arboviral symptoms, particularly fever, myalgia, joint stiffness, etc, must be considered as possible candidates for everglades viral infection.

Antibody titers in dogs naturally wane to low levels after a 1- to 2-year period[8].


  1. CDC
  2. Davis MH et al (1966) Mosquito transmission of Venezuelan equine encephalomyelitis virus from experimentally infected dogs. Am J Trop Med Hyg 15:227–230
  3. Ehrenkranz NJ et al (1970) The natural occurrence of Venezuelan equine encephalitis in the United States. N Engl J Med 282:298–302
  4. Mackenzie RB (1972) The role of silent vertebrate hosts in epidemics of Venezuelan encephalitis. In: Proceedings of the Workshop-Symposium on Venezuelan Encephalitis Virus. Scientific pub. no. 243, Washington: Regional Office of the World Health Organization
  5. Dickerman RW et al (1973) The involvement of dogs in endemic cycles of Venezuelan encephalitis virus. Am J Epidemiol 98:311–314
  6. Scherer WF et al (1972) Observations of equines, humans and domestic and wild vertebrates during the 1969 equine epizootic and epidemic of Venezuelan encephalitis in Guatemala. Am J Epidemiol 95:255–266
  7. Coffey LL et al (2006) Serologic evidence of widespread everglades virus activity in dogs, Florida. Emerg Infect Dis 12(12):1873-1879
  8. Nichols JB et al (1975) An evaluation of military sentry dogs as a sentinel system to Everglades virus (Venezuelan equine encephalitis FE3–7C strain). Mil Med 140:710–712