Eastern equine encephalitis in Tennessee: 2002-2008.
Abstract: Human and equine outbreaks caused by eastern equine encephalomyelitis virus (EEEV) typically occur in North America adjacent to coastal wetlands associated with the presence of Culiseta melanura (Coquillet) mosquitoes. Eastern equine encephalomyelitis (EEE) is an emerging disease in Tennessee, as the first records of equine disease began in 2002. In 2006 we trapped and tested mosquitoes for EEEV at hardwood swamps in western Tennessee that were at the epicenter of a multi-equine outbreak in fall of 2005. Additionally, the Tennessee Valley Authority tested mosquito pools collected in Tennessee swamps from 2000 to 2007 for the presence of arboviruses. Two pools of EEEV positive Culex erraticus (Dyer and Knab) mosquitoes were found (one each in 2003 and 2004) in a county adjacent to where the 2005 outbreak occurred. In 2008, another EEE outbreak involving multiple horses occurred in West Tennessee. A brain specimen was collected from a horse during this outbreak and the first isolate of EEEV from Tennessee was obtained. In total, 74,531 mosquitoes collected from 2000 to 2008 were tested via polymerase chain reaction and VecTest for EEEV. The traditional enzootic vector, Cs. melanura, was found in low numbers at all collection sites. Cx. erraticus, however, was consistently found in high numbers and was the only mosquito species in which EEEV was detected. We suggest that EEE transmission may be maintained by Cx. erraticus in a nontraditional cycle. We discuss the importance of a nontraditional cycle from the perspective of EEEV adaptation and emergence.
Publication Date: 2012-06-12 PubMed ID: 22679883DOI: 10.1603/me11151Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
- Arboviruses
- Diagnosis
- Disease control
- Disease Diagnosis
- Disease Etiology
- Disease Management
- Disease Outbreaks
- Disease Prevalence
- Disease Surveillance
- Disease Treatment
- Encephalomyelitis
- Epidemiology
- Equine Diseases
- Equine Health
- Horses
- Infectious Disease
- Mosquito-borne Diseases
- Public Health
- Vector-borne disease
- Veterinary Medicine
- Veterinary Research
Summary
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This research article discusses the outbreaks of the Eastern equine encephalomyelitis (EEE) disease in Tennessee between 2002 and 2008. The researchers highlight that the EEE disease is an emerging concern in the region and they present a potential new transmission cycle involving insects other than the traditionally implicated ones.
Background of EEE disease and its Importance in Tennessee
- Eastern equine encephalitis (EEE) is a disease caused by the Eastern equine encephalomyelitis virus (EEEV). It generally breaks out in areas near coastal wetlands in North America.
- EEEV is transmitted mainly through a mosquito species called Culiseta melanura.
- EEE is recognised as an emerging disease in Tennessee. The first records of this disease affecting horses in the region began in 2002.
Investigation on EEE occurrences
- In response to a multi-horse EEE outbreak that occurred in 2005, the research team carried out an investigation in 2006, trapping and testing mosquitoes in several hardwood swamps located in Western Tennessee, the epicenter of the outbreak.
- Furthermore, the Tennessee Valley Authority subjected mosquito pools gathered from Tennessee swamps between 2000 and 2007, to tests for arboviruses, a group of viruses that are transmitted by insects.
Results of the Investigation
- Two instances of EEEV positive mosquitoes of the Culex erraticus species were identified, one in 2003 and the other in 2004. Notably, these were found in regions neighboring the location of the 2005 EEE outbreak.
- By 2008, another EEE outbreak emerged in West Tennessee, involving multiple horses. The researchers managed to obtain a brain specimen from one of the affected horses, which led to the first isolation of EEEV in Tennessee.
- In total, there were 74,531 mosquitoes subjected to testing via polymerase chain reaction and VecTest for EEEV from 2000 to 2008.
Key Findings and Discussion
- Interestingly, they found that the mosquito species traditionally implicated in EEEV transmission, Cs. melanura, was present in low numbers at all the collection sites.
- Meanwhile, the mosquito species Cx. erraticus was consistently found in high numbers and it was the only mosquito species that tested positive for EEEV. This suggested that EEEV might be transmitted through a nontraditional cycle involving Cx. erraticus.
- The researchers emphasize the importance of understanding this possible nontraditional cycle, as it could significantly impact the adaptation and emergence of EEEV.
Cite This Article
APA
Mukherjee S, Moody EE, Lewokzco K, Huddleston DB, Huang J, Rowland ME, Wilson R, Dunn JR, Jones TF, Moncayo AC.
(2012).
Eastern equine encephalitis in Tennessee: 2002-2008.
J Med Entomol, 49(3), 731-738.
https://doi.org/10.1603/me11151 Publication
Researcher Affiliations
- Vector-Borne Disease Section, Communicable and Environmental Diseases, Tennessee Department of Health, 630 Hart Lane, Nashville, TN 37216, USA.
MeSH Terms
- Animals
- Culicidae / virology
- Disease Outbreaks
- Encephalomyelitis, Eastern Equine / epidemiology
- Encephalomyelitis, Eastern Equine / veterinary
- Female
- Horse Diseases / epidemiology
- Horses
- Tennessee / epidemiology
Citations
This article has been cited 7 times.- Williamson LE, Bandyopadhyay A, Bailey K, Sirohi D, Klose T, Julander JG, Kuhn RJ, Crowe JE Jr. Structural constraints link differences in neutralization potency of human anti-Eastern equine encephalitis virus monoclonal antibodies. Proc Natl Acad Sci U S A 2023 Mar 28;120(13):e2213690120.
- Björnström A, Blomström AL, Singh MC, Hesson JC. Sindbis virus neutralising antibodies detected in Swedish horses. One Health 2021 Jun;12:100242.
- Holmes AC, Basore K, Fremont DH, Diamond MS. A molecular understanding of alphavirus entry. PLoS Pathog 2020 Oct;16(10):e1008876.
- Lindsey NP, Staples JE, Fischer M. Eastern Equine Encephalitis Virus in the United States, 2003-2016. Am J Trop Med Hyg 2018 May;98(5):1472-1477.
- Bingham AM, Burkett-Cadena ND, Hassan HK, Unnasch TR. Vector Competence and Capacity of Culex erraticus (Diptera: Culicidae) for Eastern Equine Encephalitis Virus in the Southeastern United States. J Med Entomol 2016 Mar;53(2):473-6.
- Wang S, Mahalingam S, Merits A. Alphavirus nsP2: A Multifunctional Regulator of Viral Replication and Promising Target for Anti-Alphavirus Therapies. Rev Med Virol 2025 Mar;35(2):e70030.
- Corrin T, Ackford R, Mascarenhas M, Greig J, Waddell LA. Eastern Equine Encephalitis Virus: A Scoping Review of the Global Evidence. Vector Borne Zoonotic Dis 2021 May;21(5):305-320.
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