Date of Award

January 2020

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)


School of Public Health

First Advisor

Nathan Grubaugh


Introduction: Eastern Equine Encephalitis (EEE) is an alphavirus spread by the Culiseta melanura mosquitoe. While extremely rare, infection can lead to severe mental sequala and death, making it a public health concern for affected communities. Over the past two decades EEE outbreaks have become more frequent in occurrence and larger in size in the Northeast Region of the United States.

Objectives: The main objectives of this study are to 1) measure the association between mosquito abundance, infection rate, and disease incidence 2) characterize the relationship between seasonal climate variability in New England with Cs. melanura abundance, infection rates, and incidence of EEE in humans 3) Identify spatial patterns and distribution of vector species

Methods: Mosquito abundance, infection rate, and incidence of mammalian infection were compared using both simple linear regression techniques and the non-parametric Wilcox Rank Sum Test to determine the impact of Cs. melanura trends on EEE risk in humans. Association between infection rate and number humans/horses infected was measured using the Spearman correlation test. Statistically significant spatial clusters of mosquito abundance, infection rate, and human incidence were identified using a retrospective Poisson distribution model in SatScan v96.

Results: Mosquito abundance, infection rate, and incidence of mammalian infection were all highest in New London County, Connecticut. Abundance was higher in outbreak years compared to non-outbreak years but not significantly associated with human cases. Mean temperature during transmission season was associated with vector abundance while rainfall was not. Vector index was strongly associated with mammalian infection.

Conclusions: None of the risk factors studied contributed to EEE spillover significantly on their only. Likely, a combination of these factors and other environmental variables linked to climate change are what is causing the increased frequency of outbreaks. More mammalian data is needed to draw more concrete conclusions.


This is an Open Access Thesis.

Open Access

This Article is Open Access