Graduation Date
Spring 2026
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Dr. Jianmin Zhong
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Dr. Richard Brown
Second Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Third Committee Member Name
Dr. Karen Kiemnec-Tyburczy
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Name
Greg Hacker M.S.
Keywords
Northern California, Sceloporus occidentalis, Ixodes pacificus, Rickettsia G022, Rickettsia tillamookensis, Prevalence
Subject Categories
Biology
Abstract
With the warming climate and the potential expansion of tick ranges, it is imperative that we understand how tickborne bacteria can be transmitted from ticks to their vertebrate hosts. Rickettsia is an understudied, often pathogenic, bacterial genus that is found in Ixodes ticks. Ixodes pacificus is a common tick species throughout California that harbors multiple species of pathogenic bacteria. One of its key hosts is the western fence lizard (Sceloporus occidentalis). Other studies in Europe have found Rickettsial DNA in reptile hosts of Ixodes ticks. Previous research has detected DNA of Rickettsia phylotype G022 (G022) and Rickettsia tillamookensis in adult and nymphal I. pacificus, and in their small mammal hosts. Their presence in reptiles, however, had not been investigated. This project aimed to uncover whether G022 and R. tillamookensis can be detected in S. occidentalis. To gain insight into Rickettsia in lizards, I lasso captured and sampled 77 S. occidentalis across northwestern California and tested tissue biopsies for presence of the two bacteria using qPCR assays. Fifteen out of 77 samples tested positive for G022 (prevalence = 19.5%, 95% CI: 0.122-0.297). Eleven of 77 samples (prevalence = 14.3%, 95% CI: 0.0817-0.238) tested positive for R. tillamookensis. I discovered that heavier lizards were more likely to be infected with G022 (p = 0.01), compared to their lighter conspecifics. These findings demonstrate that reptiles may contribute to the maintenance of G022 and R. tillamookensis in their natural environment, supporting a One Health perspective that integrates ecological dynamics with risks to animal and human health.
Citation Style
APA
Recommended Citation
Kazemi, Pouya, "Detection of Rickettsia species phylotype G022 and Rickettsia tillamookensis in western fence lizards (Sceloporus occidentalis) across northwestern California" (2026). Cal Poly Humboldt theses and projects. 2541.
https://digitalcommons.humboldt.edu/etd/2541