La Crosse virus in western North Carolina: A study of epidemiological, entomological, and environmental risk factors
- WCU Author/Contributor (non-WCU co-authors, if there are any, appear on document)
- Joseph Walter Davis (Creator)
- Institution
- Western Carolina University (WCU )
- Web Site: http://library.wcu.edu/
- Advisor
- Brian Byrd
Abstract: La Crosse virus (LACV) is a mosquito-borne pathogen that is endemic to western North Carolina (NC) and is the etiological agent of La Crosse virus neuroinvasive disease (LACVND). In recent decades, LACVND cases have increasingly been reported often as part of persistent geographic foci, in Appalachian regions of the United States. The underlying environmental and entomological factors within these areas are unknown. However, previous speculation has implicated multiple factors, including increased detection. Here we conducted a two-part study to evaluate LACV risk factors in western NC. In Aim 1, we provide a surveillance summary of confirmed and probable LACVND during 2000-2020 using NC Electronic Disease Surveillance System data and describe associated demographic characteristics, spatiotemporal distribution, clinical features, and mortality rates. Our findings indicate that LACV risk persists in western NC, varying greatly by county, but remains consistently higher within a small number of counties. We identified reports of early-season cases occurring during the winter months, warranting further investigation into their cause. We also observed differences in age-specific case fatality rates; with children significantly more likely to experience seizures and encephalitis than adults. In Aim 2, we compare environmental and entomological risk factors between case and control households. Here we compare multiple environmental (e.g., weather, elevation, house and yard condition, vegetation, and animal abundance) and entomological (e.g., mosquito abundance, species proportions, oviposition activity, gonotrophic activity, and LACV infection rates) factors between six historical LACVND case residences paired by county with six non-case residences. Most notably, we found significantly higher adult and egg abundance of LACV vectors at case compared to non-case residences. We further analyzed these variables using negative binomial regression modeling to investigate species-specific differences. We found evidence of transovarial transmission of LACV in two samples of Aedes triseriatus from non-case residences. The results of our studies, contextualized within the broader literature, suggest that there are modifiable environmental and entomological risk factors that may reduce LACV exposure and disease risk and that future studies should focus on understanding human exposure and disease risk directly at the residential level in order to reduce transmission and disease burden.
La Crosse virus in western North Carolina: A study of epidemiological, entomological, and environmental risk factors
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Created on 7/1/2023
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Additional Information
- Publication
- Thesis
- Language: English
- Date: 2023
- Keywords
- Aedes triseriatus, arbovirus, La Crosse encephalitis, La Crosse virus, mosquito-borne disease, North Carolina
- Subjects
- Encephalitis
- Arbovirus infections
- Bloodborne infections
- Diseases—Risk factors
- Diptera