The Influence of Landscape on Exposure to and the Genetic Diversity of Toxoplasma gondii in Felids and Canids from Coastal California
Date of this Version
Camela, K. U. F. VanWormer, E. Cortinas, R. Uden, D. (2023). The influence of landscape on exposure to and the genetic diversity of Toxoplasma gondii in felids and canids from coastal California.
Landscape composition and anthropogenic pressure can shape the transmission of pathogens between hosts in shared or adjacent habitats. Human-driven environmental changes such as urbanization frequently increase contact between people and animals, increasing the risk for pathogens to be transmitted at the human-domestic animal-wildlife interface. Toxoplasma gondii, a globally distributed zoonotic parasite shed by domestic and wild felids, accumulates in terrestrial and aquatic environments leading to exposure in diverse hosts. As T. gondii can be spread through food webs (consumption of infected animal hosts) as well as by ingesting oocysts in contaminated soil, vegetation, and water, changes in landscape composition and configuration can impact exposure by changing contact among hosts or the potential for contacting oocysts in the environment. Although most animals and people infected with T. gondii experience mild or no clinical signs, the severity of the infection is highly dependent upon the immune system of the hosts and the strain of T. gondii involved. We used logistic regression to assess the association between landscape characteristics and T. gondii exposure as well as T. gondii genetic diversity in bobcats, coyotes, foxes, and feral domestic cats from coastal California. We analyzed anthropogenic (human population density and global human footprint), demographic (sex and age), landscape composition (urbanized, agricultural, and less developed areas), and landscape configuration (diversity and evenness indices) factors as potential predictors of exposure and infection with novel atypical genotypes. We found that landscape heterogeneity was positively associated with T. gondii exposure in feral cats. Animal age was consistently a strong predictor for exposure in all wild and domestic species. While we did not find associations between anthropogenic or landscape factors and infection with novel genotypes of T. gondii, expanded studies investigating heterogeneous landscapes, especially areas subject to human pressure and fragmentation, have the potential to uncover landscape connections to parasite diversity in domestic and wild hosts. Results from this thesis provide insight into the ecology of T. gondii transmission among sympatric hosts in heterogeneous landscapes and highlight the need for further research to identify areas where new strains of T. gondii may emerge.
Advisor: Elizabeth VanWormer
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Elizabeth VanWormer. Lincoln, Nebraska: May, 2023
Copyright © 2023 Kleidy U. F. Camela