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Eastern Equine Encephalitis (EEE)
Fact Sheet
Updated! |
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Source: Centers for Disease Control and Prevention
http://www.cdc.gov/ncidod/dvbid/arbor/eeefact.htm
Eastern
Equine
Encephalitis
(EEE)
is
caused
by a virus
transmitted
by the bite
of an
infected
mosquito with
more severe
symptoms
than for WNV.
The same
precautions
for WNV can
be used to
prevent EEE.
There is a
vaccine for
horses
against EEE
as well,
which needs
to be given
in two
doses.
Eastern Equine Encephalitis (EEE) is a mosquito-borne viral disease.
As the name
suggests,
EEE occurs
in the
eastern half
of the US.
Because of
the high
case
fatality
rate, it is
regarded as
one of the
more serious
mosquito-borne
diseases in
the United
States.
TRANSMISSION:
What is the
EEE
transmission
cycle? How
do people
become
infected
with EEE
virus?
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EEE virus is transmitted to humans through the bite of an infected
mosquito.
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The main EEE transmission cycle is between birds and mosquitoes.
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Several species of mosquitoes can become infected with EEE virus.
The most
important
mosquito
in
maintaining
the
enzootic
(animal-based,
in this
case
bird-mosquito-bird)
transmission
cycle is
Culiseta
melanura.
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Horses can become infected with, and die from, EEE virus infection.
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ETIOLOGIC
AGENT: What
causes EEE?
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Eastern equine encephalitis virus is a member of the family
Togaviridae,
genus
Alphavirus.
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Closely related to Western and Venezuelan equine encephalitis
viruses
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HUMAN
CLINICAL
FEATURES:
What type of
illness can
occur?
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Symptoms range from mild flu-like illness to encephalitis (inflammation
of the
brain),
coma and
death
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The EEE case fatality rate (the % of persons who develop the
disease
who will
die) is
35%,
making
it one
of the
most
pathogenic
mosquito-borne
diseases
in the
US
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It is estimated that 35% of people who survive EEE will have mild
to
severe
neurologic
deficits
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INCIDENCE:
How many and
where have
human
disease
cases
occurred?
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200 confirmed cases in the US 1964-present
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Average of 4 cases/year, with a range from 0-14 cases
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States with largest number of cases are Florida, Georgia, Massachusetts,
and New
Jersey.
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The enzootic (animal-based) transmission cycle is most common to
coastal
areas
and
freshwater
swamps.
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Human cases occur relatively infrequently, largely because the
primary
transmission
cycle
takes
place in
swamp
areas
where
populations
tend to
be
limited.
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RISK
GROUPS: Who
is at risk
for
developing
EEE?
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Residents of and visitors to endemic areas (areas with an established
presence
of the
virus)
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People who engage in outdoor work and recreational activities
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Persons over age 50 and younger than age 15 seem to be at greatest
risk for
developing
severe
disease
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PREVENTION: How can people avoid infection with EEE virus?
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A vaccine is available to protect equines
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People should avoid mosquito bites by employing personal and
household
protection
measures,
such as
using
insect
repellent
containing
DEET,
wearing
protective
clothing,
taking
precautions
from
dusk to
dawn
when
mosquitoes
are most
likely
to bite,
and
controlling
standing
water
that can
provide
mosquito
breeding
sites.
For more
information
about
preventing
mosquito-borne
disease
see
Preventing
West
Nile
Virus.
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SURVEILLANCE:
How is EEE
monitored?
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EEE is reportable under the National Notifiable Diseases Surveillance
System
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In 2003, EEE cases are being reported to ArboNet for the first
time.
ArboNet
is the
national,
electronic
surveillance
system
established
by CDC
to
assist
states
in
tracking
West
Nile
virus
and
other
mosquito-borne
viruses.
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Data for 1964-2000
is
posted
on this
website,
by
state,
as is a
map of cases
from
1964-1997.
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TRENDS
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Risk of exposure to infected mosquitoes increases as population
expands
into
areas
with an
established
presence
of the
virus
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CHALLENGES
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There is no licensed vaccine for human use
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There are no effective therapeutic drugs
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Unknown overwintering cycle
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Control measures expensive
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Limited financial support of surveillance and prevention
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RESEARCH
PRIORITIES
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Improve predictive capabilities
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Develop and evaluate vaccines
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Develop and evaluate therapeutic drugs
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Improve diagnostic and virus detection tests |
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