Term of Award

Spring 2015

Degree Name

Master of Science in Biology (M.S.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Biology

Committee Chair

William Irby

Committee Member 1

Lorenza Beati

Committee Member 2

Lance Durden

Abstract

Eastern Equine Encephalitis virus (EEEV) is a single-stranded RNA arbovirus (family Togaviridae; genus Alphavirus) endemic to the Atlantic seaboard, southeastern United States, and parts of South America. EEEV produces particularly severe disease in incidental (dead-end) hosts such as humans and horses, with case fatality rates in symptomatic humans and horses typically exceeding 70%. Although outbreaks of EEEV in humans and horses are sporadic in nature, the virulence and high costs associated with the virus makes EEEV of particular concern. The basic transmission cycle of EEEV is well understood: the virus is maintained enzootically by an avian-mosquito transmission cycle, with other vertebrates serving as incidental hosts. Mosquitoes with catholic feeding behaviors (e.g., Coquillettidia perturbans and Culex erraticus) are responsible for transmission of EEEV to non-avian vertebrates. Prior studies have demonstrated that EEEV is not maintained in overwintering mosquitoes or avians. Despite an inadequate avian viral reservoir and a lack of infected mosquitoes, EEEV reemerges each spring. Therefore, other vertebrates, potentially long-lived reptiles, probably serve as the reservoir host for EEEV. This study attempts to profile the relative abundance and feeding behavior of potential bridge vectors collected from locations associated with documented cases of EEEV in Southeastern Georgia, USA. Over the course of two years, over 7000 mosquitoes were collected from daytime resting sites within a 1-mile radius of confirmed equine and human cases of EEEV. Of these mosquitoes, 340 engorged specimens were identified as potential bridge vectors. We successfully sequenced a locus of the cytochrome c oxidase subunit I (COI) of blood meal hosts from 34 engorged specimens. Sequencing results confirmed that bridge vectors near collection sites engage in normal feeding behavior for their respective species, but no feeding on putative EEEV reservoir hosts was detected.

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