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The impact of temperature on the epizootic dynamics of Ambystoma tigrinum virus (ATV) epizootics in larval salamanders (Ambystoma mavortium)

Banister, Kelsey Elizabeth (2021) The impact of temperature on the epizootic dynamics of Ambystoma tigrinum virus (ATV) epizootics in larval salamanders (Ambystoma mavortium). Masters thesis, Northern Arizona University.

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Climate change could expand pathogen spatial distributions, accelerate transmission cycles, shifts host life cycles, and lead to emergence of disease in naïve host populations, all of which could have complex effects on disease. Quantitative frameworks like disease modeling are needed to improve our ability to predict the effects of climate and disease on host population dynamics. Amphibians are especially vulnerable to these changes, where populations are at risk of declining due to climate change, disease, and potential interaction between threats. Infecting salamander populations across the USA and Arizona, the effects of temperature on Ambystoma tigrinum virus (ATV) and the pathogen’s interaction with its host are not well quantified making risk prediction difficult. We hypothesize seasonal variation in temperature and the resulting fluctuations to the host’s immune system and the virus’ replication rates likely play significant roles in ATV epizootics. Using mechanistic models accounting for temperature and host susceptibility, we evaluate the effects of temperature on ATV disease dynamics at two levels: within and between hosts. To evaluate the effects of dose and temperature within a host, we conducted a viral transmission experiment using larval salamanders. This allowed us to parameterize a full model exploring the effects of temperature on seasonal epizootic dynamics. Our results reveal a clear non-linear effect of temperature on mortality and shedding rates that is likely mediated by temperature-influenced pathogen replication and host immune response, where cumulative mortality and shedding rate peak at 20°C. While an effect of temperature on average transmission rate was not observed, we show variation in host susceptibility increases with temperature. Using model simulations, we see earlier and more rapidly progressing epizootics when temperatures are fixed at 20°C. A fluctuating temperature regime under warmer early season conditions, however, predicts earlier and more rapid epizootics followed by a smaller late-season peak. Our findings demonstrate the utility of combining data and modeling techniques to better understand and forecast the effects of climate and disease on threatened host populations. Future work could link our model to projections of climate change to understand ATV risk in salamander populations in the US Southwest.

Item Type: Thesis (Masters)
Publisher’s Statement: © Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords: Amphibian; Disease Modeling; Epizootic; Epizootic Model; Infectious Disease; Ranavirus
Subjects: T Technology > TD Environmental technology. Sanitary engineering
MeSH Subjects: C Diseases > C03 Parasitic Diseases
NAU Depositing Author Academic Status: Student
Department/Unit: Graduate College > Theses and Dissertations
College of Engineering, Informatics, and Applied Sciences > School of Informatics, Computing, and Cyber Systems
Date Deposited: 01 Feb 2022 18:13
Last Modified: 28 Jun 2022 08:30
URI: https://openknowledge.nau.edu/id/eprint/5620

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