Ticks are hematophagous ectoparasites capable of transmitting various pathogens, including bacteria, protozoa, and viruses, to vertebrates. In the United States, tick-borne pathogens are responsible for around 95% of arthropod-borne diseases. Lyme disease is the most common tick-borne illness. However, emerging tick-borne viruses such as Bourbon virus (BRBV), Powassan virus (POWV), and Heartland virus (HRTV) can cause more severe health problems, including death and neurological abnormalities. The reports of molecular detection of viral RNA in field-collected ticks and serological evidence in a pilot study of wildlife species suggest the presence of these emerging viruses in Virginia. The presence poses a serious health threat, but the extent of their presence or circulation in Virginia is unknown. The objectives of the research are (1) to determine the evidence of circulation of POWV, HRTV, and BRBV in Virginia through serological assessment of domestic and wild animals in Virginia and (2) estimate transmission parameters and the basic reproduction number underlying tick-borne virus distribution and prevalence via a mathematical model. Here, we discuss the known literature relevant to tick-borne virus emergence; we assessed the presence of specific neutralizing antibodies against POWV, HRTV, and BRBV in wildlife and livestock sera collected from different health planning regions in Virginia. We used a susceptible-infected-susceptible (SIS) ordinary differential equation model to estimate transmission parameters that best describe the disease dynamics of emerging tick-borne viruses in Virginia. In our study, wildlife sera were seropositive against POWV (18%), BRBV (8%), and HRTV (5%). A wide range of different wildlife species were shown to be exposed to each virus examined. Livestock are also exposed to tick-borne viruses, with seroprevalences of 1%, 1.2%, and 8% detected in cattle for POWV, BRBV, and HRTV, respectively. We estimated the transmission rate and basic reproduction number to be 1.57 and 0.645, respectively. In conclusion, there is a widespread circulation of tick-borne viruses in western and northern Virginia within diverse species of animal populations. / Master of Science in Life Sciences / Ticks are blood-sucking ectoparasites that can transmit various pathogens, including bacteria, protozoa, and viruses, to humans and other vertebrates. In the United States, tick-borne pathogens are responsible for about 95% of all arthropod-borne disease cases. Lyme disease is the most common tick-borne illness. However, emerging tick-borne viruses such as Bourbon virus (BRBV), Powassan virus (POWV), and Heartland virus (HRTV), can cause more severe health problems, including potentially death or neurological abnormalities. The reports of molecular detection of viral RNA in field-collected ticks and serological evidence in a pilot study of wildlife species suggest the presence of these emerging viruses in Virginia. However, there is a lack of knowledge on the extent of their circulation. Firstly, this study aims to determine the evidence of circulation of POWV, HRTV, and BRBV in Virginia through serological assessment of domestic and wild animals. Secondly, this study aims to estimate transmission parameters and calculate the basic reproduction number of emerging tick-borne viruses. Evidence of prior infection against all three tick-borne viruses was detected in both wild and domestic animal species from the five Virginia health planning regions, with most samples in the study coming from southwestern and northwestern regions. In conclusion, there is a circulation of tick-borne viruses in Virginia, which is a potential threat to the public health.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115627 |
| Date | 03 July 2023 |
| Creators | Garba, Ahmed Oladayo |
| Contributors | Entomology, Eastwood, Gillian, Saucedo, Omar, Lahmers, Kevin K., Paulson, Sally L. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Coverage | Virginia, United States |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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