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Investigating the potential role of wildlife as reservoirs of Chikungunya virus: experimental infections and field studies




Blizzard, Emily Lauren, author
Bowen, Richard A., advisor
Pabilonia, Kristy, committee member
Schountz, Tony, committee member
Johnston, Matthew, committee member

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Chikungunya virus (CHIKV) is a mosquito-borne human pathogen endemic to Africa and Asia and the etiologic agent of chikungunya fever (CHIKF), a severe debilitating and often chronic arthralgic disease. The recent introduction of CHIKV into the Western Hemisphere has led to an increased initiative to investigate the role that mammals other than non-human primates might play during CHIKV sylvatic transmission cycles. The focus of the studies presented in this dissertation was to investigate the potential of several common rodent species to serve as reservoir and/or amplifying hosts for CHIKV during outbreaks in the Americas. Nine rodent species were subcutaneously inoculated with one of two strains of chikungunya virus during initial experimental infections. Of these, 7 out of 9 species became infected with CHIKV. Groundhogs (Marmota monax) were the mostly likely candidate to serve as a reservoir host in North America based on magnitude of viremia. All groundhogs included in this study developed significant viremias ranging from 4.0E2 to 1.6E6 and lasting 2-4 days post infection. The viral loads observed were sufficient to infect Ae. spp mosquitoes indicating that these animals are capable of serving as reservoir hosts. Additionally, groundhogs undergo periods of hibernation and further research is need to determine if these animals are capable of overwintering CHIKV in the U.S. Based on the findings from the CHIKV experimental infections, Cotton rats (Sigmodon hispidus), were evaluated as a laboratory animal model to study CHIKV pathogenesis. Thirteen of seventeen cotton rats developed a low-titer viremia, but no clinical or post-mortem pathological findings were observed. Mosquitoes fed on viremic cotton rats failed to become infected, suggesting that this species is not likely to play a role in CHIKV transmission cycles. Field studies investigating the likelihood of three mammals and eight reptilian and amphibian species were conducted in select regions of Cambodia and the Grand Cayman islands. Individuals from nine of eleven species examined had low levels of detectable CHIKV antibodies, suggesting that they may have been infected with CHIKV. The results of these studies provide some insight into the potential role of wildlife, mainly rodents, in CHIKV transmission cycles.


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Chikungunya virus
reservoir host
epizootic reservoir
amplifying host
sylvatic transmission


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