EEEV Transmission Cycle in
North America and Recent
Activity in the United States
John-Paul Mutebi, Ph. D.
Centers for Disease Control and Prevention
(CDC) Fort Collins, Colorado
EEE
Distribution
• Enzootic distribution
from southern Canada
(Ontario and Quebec)
to southern Argentina
in South America
Counties Reporting Human Cases
1996 – 2010
EEE
Distribution, US
Counties Reporting Positive Mosquito Pools
2003 – 2011
Counties Reporting Veterinary Cases
2003 – 2011
EEEV
Family Togaviridae, Genus Alphavirus
Genus Alphavirus:
- 28 members
- 7 complexes, WEE, BF, SF, VEE, EEE, MID and NDU
- 4 genetic lineages in the EEEV complex:
- Lineage I, North American and Caribbean
- Lineages II – IV, Central and South American
EEE Transmission Cycle
Culex, Aedes
Coquillettidia, etc.
Incidental
hosts
Culiseta melanura
&
Passerine birds
Vertebrate Host
Amplifying hosts:
• Wild birds, especially passerine birds
Incidental hosts:
• A variety of wild animals are susceptible:
- Bats
- White-tailed deer
- A variety of small mammals and marsupials
- Reptiles
- Amphibians
• Humans and equids
Mosquito Vectors
• At least 23 species in 6 genera
Ae. cantator
Cs. melanura
Ae. infirmatus
Cx. nigripalpus
An. crucians
Cq. perturbans
Ae. vexans ?
Cs. morsitans
Cs. minnesotae
Ae. sollicitans
Cx. territans
An. quadrimaculatus
Ur. sapphirina
Cx. salinarius
Cx. quinquefasciatus
Cx. pipiens
Ae. triseriatus
Cx. restuans
Ae. mitchellae
Ae. canadensis
An. punctipennis
Ae. atlanticus/tormentor
Distribution of EEE
Veterinary Cases and
of Common EEEV
Vectors in the US
Distribution Ranges of Common Vectors of EEEV in North America
(Darsie and Ward 2005)
Coquillettidia pertubans
Aedes sollicitans
Culiseta melanura
Typical Habitat
• Primarily lowland swamps with muck-peat soil and
hardwoods (red maple, hornbeam, cedar and loblolly
bay, swamp and sweet bay, black gum, sweet gum)
Country or State
Predominant Hardwood
Canada
New York
Massachusetts
Michigan
red maple, hornbeam
New Jersey
Maryland
red maple, cedar
Florida
Loblolly bay, swamp and sweet
bay, black gum, sweet gum
Eastern Equine Encephalitis Virus
Total Cases in U.S. 1964-2011
2010: 10 Total Cases
4 FL, 3 MI, 1 MA, 1 NY, 1RI
2005: 21 Total Cases
7 NH, 5 FL, 4 MA, 2 AL
1 GA, 1 LA, 1 SC
Eastern Equine Encephalitis activity reported to ArboNET, by
State, United States, 2011 (as of January 10, 2012)
Neuroinvasive
disease cases
Non-Neuro
cases
Total
Massachusetts
1
-
1
Missouri*
1
-
1
New York
1
-
1
Wisconsin
1
-
1
Total
4
-
4
* Missouri case acquired
in Massachusetts
• 4 cases reported from 4 states
• Enzootic activity detected in
11 additional states
Eastern Equine Encephalitis
Number of Cases
Veterinary Cases in the US 2003-2011
Total = 2,337
Cases/Year = 257
Eastern Equine Encephalitis
Veterinary Cases in the US 2003
Total Cases = 712
States Reporting = 17
States = 16
States = 18
States = 17
States = 10
Outbreaks in FL,
MS and LA every
Year since 2003
Combined 2009 and 2010 data:
• Samples were collected from
15 of Maine’s 16 counties
• Positives were found in 10
counties
• 11.6 overall percent of deer
were positive
• 10.3 overall percent of moose
were positive
• 2 bears were tested, neither
were positive
Distribution of
EEE Positive
Sera
Samples in
Vermont,
2010
2011 EEE
Positive Emu
• 1 Bird Tested Positive
• Reported 9/22
• 19 Birds Died out of
100
• 2 Birds Sick but
Recovered
Selected Refernces
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Centers for Disease Control and Prevention. Chart: Confirmed and probable eastern equine encephalitis cases, human, United States, 19642011, by state. Available at http://www.cdc.gov/ncidod/dvbid/Arbor/pdf/EEE_DOC.pdf., 2011.
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Equine Encephalitis Cases in the United States. 2009 March 13. Available from http://www.aphis.usda.gov/vs/nahss/equine/ee/
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AKNOWLEDGEMENTS
Maine
Stephen Sears, Maine CDC
Sara Robinson, Maine CDC
Charles Lubelczyk, Maine Medical Research Center
Vermont
Erica Berl, Vermont Department of Health
Alan Graham, Vermont Agency of Agriculture
Jon Turmel, Vermont Agency of Agriculture
CDC
Jennifer Lehman
Bethany Swope
Marvin Godsey
Nick Panella
Ginger Young
Rebecca Eisen
Katherine MacMillan