Graduation Year


Document Type




Degree Name

Master of Science (M.S.)

Degree Granting Department

Geography, Environment and Planning

Major Professor

Joni Downs Firat, Ph.D.

Committee Member

Thomas Unnasch, Ph.D.

Committee Member

Ran Tao,Ph.D.


Drought, Eastern Equine Encephalitis Virus, Precipitation, VPDmax, VPDmin, Wintertime, Temperature


Eastern Equine encephalitis virus (EEEV) is a highly pathogenic alphavirus that causes disease in humans and horses. EEEV cases are common in the eastern North America, especially in horses in the State of Florida. EEEV cases are most common in Florida during May to August but also occur year-round, unlike most other locations. According to the Florida Department of Health, 65 EEEV horse cases were documented in the winter months between 2005 and 2018. This study investigates the meteorological activities that affect the wintertime transmission of the EEEV virus to horses. In this, we examined meteorological data up to a year before the onset of the case. Specifically, we analyzed temperatures, precipitation, and drought. Fifty-six of 65 cases occurred when rain was observed in the previous 10 days. Sixty-one occurred when four or fewer days of freezing temperatures were observed in the previous 4 weeks. Forty-six cases occurred when drought or abnormally dry conditions occurred in the prior 16 weeks. Given that drought and freezing temperatures are relatively uncommon, these results suggest that cases are associated with mild temperatures occurring with abundant rainfall following previously dry conditions.