Factors that affect Culex mosquito feeding choice in Atlanta, Georgia Public

Abstract

Background

Since its introduction in 1999, West Nile Virus (WNV), a mosquito-borne zoonosis, has spread throughout the United States. Enzootic transmission occurs between female mosquitoes of the genus Culex, and various passerine birds. Humans, who are dead-end hosts, can become infected following the bite of an infected mosquito. Therefore, any factors that may affect mosquito host choice are likely to have an impact on the probability of WNV transmission to humans. A feeding shift from avian to mammalian species may contribute to the WNV transmission patterns in the eastern U.S. In addition, mosquito host choice is one of the key parameters of mathematical models that predict pathogen transmission.

Methods

A total of 86 blood fed mosquitoes were processed from Tanyard Creek and Peavine Creek in Atlanta, Georgia over 2010 and 2011. The mosquitoes were analyzed for blood meal sources using hemi-nested PCR protocols targeted at the 16S ribosomal gene. The samples were then sequenced in order to identify the host to the species level. Fisher's exact tests were performed on dichotomized variables such as creek, year, and season. Lastly, logistic regression was performed to identify any significant additional predictors that could yield information on mosquito host choice

Results

The Fisher's exact test suggested that the dichotomous variable creek was significantly associated with the number of blood meals that were avian or human in origin (p=0.0163, p=0.0231) while year was significantly associated with the number of human blood meals (p=0.0002). Results from a stepwise logistic regression suggested that creek was the only significant predictor associated with avian versus non-avian blood meals and year was the only predictor with significantly associated with feeding preference between human versus non-human blood meal sources (p<0.001). Month and season were not associated with host choice.

Conclusion

The significant association of creek and year with feeding preference is in agreement with the notion that Culex spp. are opportunistic feeders that can shift between blood meal sources based on availability, rather than being limited by season. This opportunistic nature is in agreement with the hypothesized role of Culex spp. as vectors for enzootic transmission and as bridge vectors to humans.

Table of Contents

Introduction Methods Field sampling Blood meal identification Data processing and analysis Results Mosquito collections, species, Sella scores Blood meal analysis Analytic statistics Discussion Future Directions Tables Figures and Graphs Appendix A: Laboratory protocols

About this Master's Thesis

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• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Global Epidemiology - MPH & MSPH
Degree	MSPH
Submission	Master's Thesis
Language	English
Research Field	Biology, Ecology Biology, Molecular Biology, Entomology
Mot-clé	West Nile Virus Infectious Disease Feeding Choice Mosquitoes
Committee Chair / Thesis Advisor	Vazquez Prokopec, Gonzalo, Emory University Kitron, Uriel, Emory University
Committee Members	Marcet, Paula, Centers for Disease Control and Prevention
Partnering Agencies	Emory University schools, faculty or affiliated programs CDC

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