Graduation Date
Fall 2022
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Jianmin Zhong
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Richard Brown
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Allison Bronson
Third Committee Member Affiliation
HSU Faculty or Staff
Fourth Committee Member Name
Jeremy Corrigan
Fourth Committee Member Affiliation
Community Member or Outside Professional
Subject Categories
Biology
Abstract
Back in 2011 an unknown Rickettsia species was discovered in adult Ixodes pacificus and became known as Rickettsiaspecies phylotype G022. Preliminary analyses placed it among the Spotted Fever Group Rickettsia, indicating unknown pathogenicity. Another Rickettsia species previously found in I. pacificus, R. tillamookensis, was only recently the subject of research efforts after its original discovery in the 1960s. The main focus of this research was to determine the prevalence of phylotype G022 in nymphal I. pacificus to gain further insight into this tick-Rickettsia relationship. The prevalence of R. tillamookensis was also a topic of this research to add more California counties to the data. For this study, nymphal I. pacificus were collected from Humboldt, Contra Costa, Napa, Mendocino, Sonoma, and Santa Cruz counties in California and real-time PCR was used to determine the prevalence of phylotype G022 and R. tillamookensis. The prevalence of phylotype G022 in I. pacificus nymphs is 5.27% and the prevalence of R. tillamookensis is 1.59%. The co-infection rate between R. monacensis str. Humboldt and phylotype G022 was 31.87% and for R. tillamookensis it was 7.69%. None of the nymphs were infected with all three Rickettsia species. Spearman’s rank correlation test conveyed that there was either a weak or absent statistically significant correlation between the endosymbiont and either of the two Rickettsia species. This research showed that phylotype G022 can inhabit nymphal I. pacificus, with the prevalence possibly influenced by temperature. The low prevalence of this rickettsia within adults and nymphs contributes to the thought that this species is pathogenic, with the presence of G022 in nymphs showing that this rickettsiae is transstadially transmitted.
Citation Style
CBE
Recommended Citation
Trent, Erin Rose, "Prevalence of Rickettsia sp. phylotype G022 and Rickettsia tillamookensis in Ixodes pacificus nymphs from Northern California" (2022). Cal Poly Humboldt theses and projects. 613.
https://digitalcommons.humboldt.edu/etd/613
Included in
Bacteriology Commons, Biology Commons, Other Microbiology Commons
Comments
This data belongs to Erin R. Trent and Jianmin Zhong and any usage or reference to this research must be properly cited to give credit to these individuals.