SPECTRE Blog

EASTERN EQUINE ENCEPHALITIS (EEE) SENTINEL ANIMALS

OVERVIEW

Eastern Equine Encephalitis Virus (EEEV) is an arthropod-borne virus that primarily causes mild fever in humans and horses but escalates to encephalitis and death in a small percentage of individuals. While humans and horses are dead-end hosts–within whom the virus can infect but cannot replicate sufficiently enough to be transmitted again–other animals serve as reservoirs and mobilizers of the virus. Therefore, numerous projects have been conducted to monitor the presence of EEEV antibodies in various animals, which has led to an improved understanding of the virus’ current life cycle and has aided in forecasting the spread of disease.

CHICKEN COOPS IN FLORIDA

Chickens play a major role in tracking EEEV in Florida, currently the largest hotspot for the pathogen. Sentinel coops were first established in 1978 in response to an unprecedented outbreak of St. Louis Encephalitis Virus (another local cause of viral encephalitis), and are maintained in areas determined to be at-risk for several arboviruses, including EEEV [Beeman et al., 2022]. Since chickens are asymptomatic carriers of EEEV, they are ideal animals to be routinely sampled for EEEV antibodies. When chickens positive for EEEV are discovered, their location is documented and shared with epidemiological research teams dedicated to monitoring the pathogen. Within the past few years, several epidemiological models (e.g., risk index, overlay, and time series models) have been created to track future outbreaks [Beeman et al., 2022; Mundis et al, 2022].

WILD CERVIDS IN NORTHEASTERN US

EEEV antibodies have also been sampled in wild cervids such as white-tailed deer and moose in the northeastern U.S. One recent study collecting data from Maine, Vermont, and New Hampshire suggested the geographical extent of EEEV is greater than previously assumed [Mutebi et al, 2022]. While these findings are concerning, this research team believes continuing their sampling techniques will aid in a better understanding of the viral transmission cycle in the Northeast, which will lead to a better prediction of future outbreaks.

Taylor is a medical student at the University of Texas Medical Branch in Galveston. She is hoping to pursue her interest in infectious diseases by specializing in Internal Medicine or Pathology.

References

Beeman, S. P., Downs, J. A., Unnasch, T. R., & Unnasch, R. S. (2022). West nile virus and eastern equine encephalitis virus high probability habitat identification for the selection of sentinel chicken surveillance sites in florida. Journal of the American Mosquito Control Association, 38(1), 1-6. doi:https://doi.org/10.2987/21-7049

Stephanie J Mundis, Steve Harrison, Dave Pelley, Susan Durand, Sadie J Ryan, Spatiotemporal Environmental Drivers of Eastern Equine Encephalitis Virus in Central Florida: Towards a Predictive Model for a Lethal Disease, Journal of Medical Entomology, Volume 59, Issue 5, September 2022, Pages 1805–1816, https://doi-org.libux.utmb.edu/10.1093/jme/tjac113

John-Paul Mutebi, Abigail A Mathewson, Susan P Elias, Sara Robinson, Alan C Graham, Patti Casey, Charles B Lubelczyk, Use of Cervid Serosurveys to Monitor Eastern Equine Encephalitis Virus Activity in Northern New England, United States, 2009–2017, Journal of Medical Entomology, Volume 59, Issue 1, January 2022, Pages 49–55, https://doi.org/10.1093/jme/tjab133


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