Graduation Year

2020

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Public Health

Major Professor

Thomas R. Unnasch, Ph.D.

Committee Member

Joni Downs, Ph.D.

Committee Member

Lynn Martin, Ph.D.

Committee Member

Nathan D. Burkett-Cadena, Ph.D.

Committee Member

Benjamin Jacob, Ph.D.

Keywords

Arbovirus, EEEV, ENSO, GIS, Host Use, Risk Index

Abstract

Eastern Equine Encephalitis virus (EEEV) is considered the most pathogenic mosquito-borne illness in the United States. Human mortality has been estimated to range between 35 to 75%, with horses experiencing mortality rates greater than 90%. A large number of EEEV cases occur in Florida. Though we have come a long way since the first human infection was identified in the 1930s, there is still much to learn regarding the virus’s ability to maintain transmission year-round in Florida. Phylogenic studies support that Florida may serve as the geographic reservoir for EEEV. This research investigated spatiotemporal and ecological variables associated with risk for EEEV transmission during winter-spring seasons when vector abundance is low, yet EEEV activity is still present. A lag effect was demonstrated using the Southern Oscillation Index (SOI) that is predictive for EEEV equine outbreaks. Secondly this research sought to identify areas of high-risk for EEEV activity using GIS-based risk index modelling. Although mosquito abundance was low during winter field collections Culiseta melanura the major enzootic vector of EEEV was present in reasonable numbers at high risk sites in the winter and early spring months, while almost none were found at low-moderate risk sites. EEEV activity was also only detected in GIS-predicted high-risk sites. Combined these results offer models that can predict EEEV activity which could be used for optimization of surveillance and control strategies that protect against EEEV in Florida.

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