DR WAQAS NAWAZ PMAS Arid Agriculture University, Rawalpindi Pakistan

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Synonymous:
 EEE
 Triple-E
 Sleeping Sickness
But not be confused with Trypnosomiasis (sleeping sickness) because that only prevails
in Africa while EEE can be in regions other than Africa.
Host Range:
Equines
Reptiles
Birds
Amphibians
Variety of Mammals & vertebrates including human
Etiology:
It is a viral disease
Family-------------Togaviridae
Genus--------------Alphavirus
Species-------------EEE virus
RNA virus has zoonotic importance. It is present in North, Central & South America & the
Caribbean. EEEV is closely related to Venezuelan equine encephalitis virus and Western
equine encephalitis virus.
History:
 EEE was first recognized in USA in 1831 when 75 horses died of encephalitic illness
 After that outbreaks have continued to occur regularly in USA & are more associated
with coastal plains.
 In 1938, the first confirmed human cases were identified when thirty children died of
encephalitis in the northeastern United States. These cases were also linked with
outbreaks in horses in the same regions. USA researched it as potential biological agent.
 October 2007, the first European victim was recognized, that was a citizen of Scotland.
He was diagnosed with EEE virus when he just returned home after visiting the USA on a
fishing vacation.

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Life Cycle:
 The virus is maintained in nature through a bird - mosquito cycle.
 Two mosquito species primarily involved in this portion of the cycle; Genus Culiseta
o Culiseta melanura
o Cs. morsitans.
 These mosquitoes feed on the blood of birds
 The amount of virus found in nature increases throughout the summer as more birds and
more mosquitoes become infected
 These other mosquitoes are called bridge vectors because they carry the virus from the
avian hosts to other types of hosts, particularly mammals
Transmission (In Body of Horses)):
After inoculation by the vector, the virus travels via lymphatics to lymph nodes
Replicates in macrophages and neutrophils resulting in lymphopenia, leukopenia and
fever.
Subsequent replication occurs in other organs leading to viremia.
Clinical Signs & Symptoms:
 Symptoms occur 1-3 weeks after infection
 High fever is the first sign (106°F), lasts for 24-48 hour
 Nervous signs appear during the fever that includes;
o Sensitivity to sound
o Periods of excitement
o Restlessness
 Brain lesions appear, causing;
o Drowsiness
o Drooping ears

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o Circling
o Aimless wandering
o Head pressing
o Inability to swallow
o Abnormal gait
 Paralysis follows, causing the horse to have difficulty raising its head.
 The horse usually suffers complete paralysis and death two to four days after symptoms
appear.
 Mortality rates = 70 to 90%
 In Humans: (Symptoms occur 3-10 days after the bite of infected mosquito)
o High fever
o Muscle pain
o Headache
o Photophobia
o Seizures
Diagnosis:
 Clinical sign & symptoms
 Lab tests
o Isolation of virus
o Demonstration of specific viral antigen in Serum or CSF
o VNT
o ELISA
Treatment & Prognosis:
No specific treatment
Corticosteroids
Anticonvulsants
Supportive measures (treating symptoms) such as intravenous fluids, tracheal intubation,
and antipyretics
About 4% human known to be infected develop symptoms. In human, USA, 5-10 (average 6)
cases per year are identified with 33-35% case fatality rate. A third of these cases develop
permanent brain damage.
Prevention:
 The disease can be prevented in horses with the use of vaccinations.
 These vaccinations are usually given together with vaccinations for other diseases, most
commonly WEE,VEE, and tetanus.
 Most vaccinations for EEE consist of killed virus
Confirm Dx:
Virus-specific IgM antibodies in CSF or serum