Graduation Date
Spring 2025
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Jianmin Zhong
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Megan E. M. Saunders
Second Committee Member Affiliation
Community Member or Outside Professional
Third Committee Member Name
Robert S. Lane
Third Committee Member Affiliation
Community Member or Outside Professional
Fourth Committee Member Name
Karen Kiemnec-Tyburczy
Fourth Committee Member Affiliation
Cal Poly Humboldt Faculty or Staff
Keywords
Ixodes pacificus, Rickettsia, G022, Rickettsia tillamookensis, Northern California, Small mammals, Fleas, Foxes
Subject Categories
Biology
Abstract
Ticks are important vectors of numerous pathogenic bacteria including those belonging to the genus Rickettsia. Two Rickettsia species that have been detected in the western blacklegged tick (Ixodes pacificus), i.e., Rickettsia species phylotype G022 and R. tillamookensis, are of unknown pathogenicity and their potential for infecting vertebrates has not been studied heretofore. The results of previous research suggest that both species may potentially depend on horizontal transmission to sustain infection in natural populations of ticks. Additionally, their presence in other ectoparasites, such as fleas, remains unexplored. This study aimed to determine the prevalence of G022 and R. tillamookensis in ear-punch biopsies obtained from small mammals collected from 11 counties in northwestern California and in adult fleas combed from the fur of small mammals solely in Humboldt County. Real-time quantitative PCR analysis revealed that the prevalence of G022 and R. tillamookensis in small mammals was 5.9% for G022 and 1.1% for R. tillamookensis. Similarly, the prevalence of G022 and R. tillamookensis in adult fleas was 4.8% and 1.6%, respectively. Molecular detection of G022 and R. tillamookensis in small mammals and fleas indicate that these bacteria may contribute to their persistence in I. pacificus. An indirect immunofluorescence assay revealed that one gray fox (Urocyon cinereoargenteus) tested for presence of Rickettsia species may have seroconverted against R. tillamookensis-like microorganisms. The results of this study provide the foundations for future investigations into the transmission routes of G022 and R. tillamookensis within populations of small mammals and other ectoparasites besides I. pacificus.
Citation Style
ASM
Recommended Citation
Kwon, Oh Byung, "Molecular and serological detection of Rickettsia species phylotype G022 and Rickettsia tillamookensis in small mammals and fleas in northwestern California" (2025). Cal Poly Humboldt theses and projects. 2292.
https://digitalcommons.humboldt.edu/etd/2292
Comments
This data belongs to Oh Byung Kwon and Jianmin Zhong and any usage or reference to this research must be properly cited to give credit to these individuals.