Prepared by:
Alexander Sonneborn
Cornell Biological Field Station
April 2007
Electron microscope photo of EEE
(Photo credit: CDC)
EASTERN EQUINE ENCEPHALITIS
(Family: Togaviridae)
EEE is most active between late July and September. In
humans infected with EEE, symptoms appear three to ten
days after being bitten, and include high fever (103º to 106º
F), stiff neck, headache, and lack
of energy. Encephalitis (brain
inflammation and swelling) is the
most dangerous symptom and
sets in next. The disease worsens
quickly, and some patients go
into a coma within a week. In
infected humans, EEE has a
fatality rate of around 35%.
• Occurs primarily in the northeast U.S.
• Fatality rate around 35% in humans
• Infected mosquitoes found near Oneida Lake
Though eastern equine encephalitis (EEE) was first observed
in Massachusetts in 1831 when 75 horses died, a human case
was not recorded until 1938 when 30 children died. Today,
EEE is found in freshwater swamps in the eastern U.S. (like
Cicero Swamp), where it is spread from bird to bird by
infected mosquitoes. Though capable of infecting mammals,
birds, reptiles and amphibians, most animals never develop
high enough levels of the virus to become sick or contagious.
EEE has been identified in: MA, NH,
NY, PA, DE, MD, VA, NC, SC, GA, FL,
AL, MS, LA, TX, WI, MI, and IN
Oneida Lake Status:
Present
EEE is spread by mosquitoes (Photo
credit: CDC)
On July 14th, 2005, despite low mosquito numbers, a Cicero
Swamp mosquito tested positive for EEE virus. The
following week a cattail mosquito (a known human biter)
also tested positive. In response, 7,700 acres of Cicero
Swamp received an aerial application of mosquito
adulticides. No EEE activity was detected in Onondaga
County for the remainder of that season. On August 17,
2006, aerial spraying was conducted over the Toad Harbor
Swamp and some surrounding areas on the north shore of
Oneida Lake. This was prompted when EEE infected
mosquitoes were found in several areas.
Brain section from a horse infected
with EEE (www.medscape.com)