Volume 79, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


Epidemics and epizootics of eastern equine encephalitis virus (EEEV) occur sporadically in temperate regions where transmission is seasonal from late summer to early fall. These outbreaks may derive from virus that overwinters locally or perhaps results from reintroduction of virus from other sites. To evaluate these possibilities, we compared the phylogenetic relationships of EEEV isolates obtained from mosquitoes collected during statewide arbovirus surveillance in Connecticut, in addition to isolates from concurrent outbreaks in southern New Hampshire and upstate New York. In Connecticut, viral isolates grouped into temporally discrete clades by year of isolation or over 2 years of sampling. Two or more clades arose in 2000, 2001, 2003, 2004, and 2006, possibly the result of separate introduction events into the state, whereas viruses from upstate New York and New Hampshire segregated into single clades that persisted for 2 or more years. New Hampshire viruses shared recent common ancestry to those isolated in Connecticut suggesting viral dispersal among these regions. These results provide additional evidence for independent episodes of EEEV overwintering in northern foci.


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  1. Morris CD, 1988. Eastern equine encephalomyelitis. Monath TP, ed. The Arboviruses: Epidemiology and Ecology. Boca Raton, FL: CRC Press, 1–20.
  2. Scott TW, Weaver SC, 1989. Eastern equine encephalomyelitis virus: epidemiology and evolution of mosquito transmission. Adv Virus Res 37 : 277–328. [Google Scholar]
  3. Bigler WJ, Lassing EB, Buff EE, Prather EC, Beck EC, Hoff GL, 1976. Endemic eastern equine encephalomyelitis in Florida: a twenty-year analysis, 1955–1974. Am J Trop Med Hyg 25 : 884–890. [Google Scholar]
  4. Deresiewicz RL, Thaler SJ, Hsu L, Zamani AA, 1997. Clinical and neuroradiographic manifestations of eastern equine encephalitis. N Engl J Med 336 : 1867–1874. [Google Scholar]
  5. Weaver SC, Hagenbaugh A, Bellew LA, Gousset L, Mallampalli V, Holland JJ, Scott TW, 1994. Evolution of alphaviruses in the eastern equine encephalomyelitis complex. J Virol 68 : 158–169. [Google Scholar]
  6. Young DS, Kramer LD, Maffei JG, Dusek RJ, Backenson PB, Mores CN, Benard KA, Ebel GD, 2008. Molecular Epidemiology of Eastern Equine Encephalitis Virus, New York. Emerg Infect Dis 14 : 454–460. [Google Scholar]
  7. Weaver SC, Scott TW, Rico-Hesse R, 1991. Molecular evolution of eastern equine encephalomyelitis virus in North America. Virology 182 : 774–784. [Google Scholar]
  8. Brault AC, Powers AM, Chavez CL, Lopez RN, Cachon MF, Gutierrez LF, Kang W, Tesh RB, Shope RE, Weaver SC, 1999. Genetic and antigenic diversity among eastern equine encephalitis viruses from North, Central, and South America. Am J Trop Med Hyg 61 : 579–586. [Google Scholar]
  9. Andreadis TG, Anderson JF, Vossbrinck CR, Main AJ, 2004. Epidemiology of West Nile virus in Connecticut: a five-year analysis of mosquito data 1999–2003. Vector Borne Zoonotic Dis 4 : 360–378. [Google Scholar]
  10. Andreadis TG, Anderson JF, Tirrell-Peck SJ, 1998. Multiple isolations of eastern equine encephalitis and highlands J viruses from mosquitoes (Diptera: Culicidae) during a 1996 epizootic in southeastern Connecticut. J Med Entomol 35 : 296–302. [Google Scholar]
  11. Centers for Disease Control and Prevention, 2006. Eastern equine encephalitis—New Hampshire and Massachusetts, August–September 2005. MMWR Morb Mortal Wkly Rep 55 : 697–700. [Google Scholar]
  12. Molaei G, Oliver J, Andreadis TG, Armstrong PM, Howard JJ, 2006. Molecular identification of blood-meal sources in Culiseta melanura and Culiseta morsitans from an endemic focus of eastern equine encephalitis virus in New York. Am J Trop Med Hyg 75 : 1140–1147. [Google Scholar]
  13. Tamura K, Dudley J, Nei M, Kumar S, 2007. MEGA4: molecular evolutionary genetics analysis (MEGA) software version 4.0. Mol Biol Evol 24 : 1596–1599. [Google Scholar]
  14. Swofford D, 2001. PAUP* 4.0, Phylogenetic Analysis Using Parsimony and Other Methods. Sunderland, MA: Sinauer Associates.
  15. Posada D, Crandall KA, 1998. Modeltest: testing the model of DNA substitution. Bioinformatics 14 : 817–818. [Google Scholar]
  16. Farris JS, Kallersjo M, Kluge AG, Bult C, 1994. Testing the significance of incongruence. Cladistics 10 : 315–319. [Google Scholar]
  17. Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ, 1990. Basic local alignment search tool. J Mol Biol 215 : 403–410. [Google Scholar]
  18. Weaver SC, Bellew LA, Gousset L, Repik PM, Scott TW, Holland JJ, 1993. Diversity within natural populations of eastern equine encephalomyelitis virus. Virology 195 : 700–709. [Google Scholar]
  19. Scott TW, 1988. Vertebrate host ecology. Monath TP, ed. The Arboviruses: Epidemiology and Ecology. Boca Raton, FL: CRC Press, 257–280.
  20. Jamnback H, 1961. Culiseta melanura (Coq.) breeding on Long Island, N.Y. Mosquito News 21 : 140–141. [Google Scholar]
  21. Wallis RC, 1962. Overwintering Culiseta melanura larvae. Proc Entomol Soc Wash 64 : 119–122. [Google Scholar]
  22. Chamberlain RW, Sudia WD, 1961. Mechanism of transmission of viruses by mosquitoes. Annu Rev Entomol 6 : 371–390. [Google Scholar]
  23. Hayes RO, Daniels JB, Anderson KS, Parsons MA, Maxfield HK, LaMotte LC, 1962. Detection of eastern encephalitis virus and antibody in wild and domestic birds in Massachusetts. Am J Hyg 75 : 183–189. [Google Scholar]
  24. Morris CD, Srihongse S, 1978. An evaluation of the hypothesis of transovarial transmission of eastern equine encephalomyelitis virus by Culiseta melanura. Am J Trop Med Hyg 27 : 1246–1250. [Google Scholar]
  25. Sprance HE, 1981. Experimental evidence against the transovarial transmission of eastern equine encephalitis virus in Culiseta melanura. Mosquito News 41 : 168–173. [Google Scholar]
  26. Watts DM, Clark GG, Crabbs CL, Rossi CA, Olin TR, Bailey CL, 1987. Ecological evidence against vertical transmission of eastern equine encephalitis virus by mosquitoes (Diptera: Culicidae) on the Delmarva Peninsula, USA. J Med Entomol 24 : 91–98. [Google Scholar]
  27. Wallis RC, Taylor RM, McCollum RW, Riordan JT, 1958. Study of hibernating mosqutioes in eastern equine encephalomyelitis epidemic areas in Connecticut. Mosquito News 18 : 1–4. [Google Scholar]
  28. Crans WJ, Caccamise DF, McNelly JR, 1994. Eastern equine encephalomyelitis virus in relation to the avian community of a coastal cedar swamp. J Med Entomol 31 : 711–728. [Google Scholar]
  29. Emord DE, Morris CD, 1984. Epizootiology of eastern equine encephalomyelitis virus in upstate New York, USA. VI. Antibody prevalence in wild birds during an interepizootic period. J Med Entomol 21 : 395–404. [Google Scholar]
  30. Howard JJ, Oliver J, Grayson MA, 2004. Antibody response of wild birds to natural infection with alphaviruses. J Med Entomol 41 : 1090–1103. [Google Scholar]

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  • Received : 17 Mar 2008
  • Accepted : 08 May 2008

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