Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-3 (of 3 Records) |
Query Trace: Yoshimizu MH[original query] |
---|
A novel TaqMan assay to detect Rickettsia 364D, the etiologic agent of Pacific Coast tick fever.
Karpathy SE , Espinosa A , Yoshimizu MH , Hacker JK , Padgett KA , Paddock CD . J Clin Microbiol 2019 58 (1) Pacific Coast tick fever is a febrile illness associated with the bite of Dermacentor occidentalis and results from an infection due to the intracellular pathogen Rickettsia 364D (also known by the proposed name "Rickettsia philipii"). Current molecular methods for the detection of this pathogen rely on the amplification of a conserved spotted fever group rickettsial gene (ompA) followed by DNA sequencing of the amplicon to identify the species. This work describes the development of a Rickettsia 364D-specific TaqMan assay to simplify and accelerate the detection and identification processes. The assay demonstrated a sensitivity of 1 genomic copy per 4 mul sample and is highly specific for Rickettsia 364D. The utility of this assay for ecological and diagnostic samples was evaluated using single-blinded banked specimens and yielded a clinical sensitivity and specificity of 100%. In conclusion, we describe the development and evaluation of a novel TaqMan real-time PCR assay for the detection and identification of Rickettsia 364D suitable for ecological and diagnostic applications. |
Rickettsia species isolated from Dermacentor occidentalis (Acari: Ixodidae) from California
Paddock CD , Yoshimizu MH , Zambrano ML , Lane RS , Ryan BM , Espinosa A , Hacker JK , Karpathy SE , Padgett KA . J Med Entomol 2018 55 (6) 1555-1560 The Pacific Coast tick (Dermacentor occidentalis Marx, 1892) is one of the most widely distributed and frequently encountered tick species in California. This tick is the primary vector of an unclassified spotted fever group rickettsial pathogen, designated currently as Rickettsia 364D, the etiologic agent of a recently recognized tick-borne rickettsiosis known as Pacific Coast tick fever. Despite intensified interest in this pathogen, important questions remain regarding its taxonomic status and possible variations in genotype among different strains that could influence its pathogenicity. Only the extensively passaged prototypical isolate (strain 364-D) is widely available to rickettsiologists and public health scientists worldwide. To achieve a larger, more geographically diverse, and contemporary collection of strains, 1,060 questing adult D. occidentalis ticks were collected from 18 sites across six counties in northern and southern California in 2016 and 2017. Fourteen ticks (1.3%) yielded DNA of Rickettsia 364D and from these, 10 unique isolates from Lake and Orange counties were obtained. Additionally, Rickettsia rhipicephali was detected in 108 (10.2%) ticks, from which eight isolates were obtained, and Rickettsia bellii in six (0.6%), from which three isolates were obtained. The panel of recently acquired, low-passage strains of Rickettsia 364D derived from this study could enhance opportunities for investigators to accurately determine the taxonomic standing of this agent and to develop specific diagnostic assays for detecting infections with Rickettsia 364D in ticks and humans. |
The eco-epidemiology of Pacific Coast tick fever in California
Padgett KA , Bonilla D , Eremeeva ME , Glaser C , Lane RS , Porse CC , Castro MB , Messenger S , Espinosa A , Hacker J , Kjemtrup A , Ryan B , Scott JJ , Hu R , Yoshimizu MH , Dasch GA , Kramer V . PLoS Negl Trop Dis 2016 10 (10) e0005020 Rickettsia philipii (type strain "Rickettsia 364D"), the etiologic agent of Pacific Coast tick fever (PCTF), is transmitted to people by the Pacific Coast tick, Dermacentor occidentalis. Following the first confirmed human case of PCTF in 2008, 13 additional human cases have been reported in California, more than half of which were pediatric cases. The most common features of PCTF are the presence of at least one necrotic lesion known as an eschar (100%), fever (85%), and headache (79%); four case-patients required hospitalization and four had multiple eschars. Findings presented here implicate the nymphal or larval stages of D. occidentalis as the primary vectors of R. philipii to people. Peak transmission risk from ticks to people occurs in late summer. Rickettsia philipii DNA was detected in D. occidentalis ticks from 15 of 37 California counties. Similarly, non-pathogenic Rickettsia rhipicephali DNA was detected in D. occidentalis in 29 of 38 counties with an average prevalence of 12.0% in adult ticks. In total, 5,601 ticks tested from 2009 through 2015 yielded an overall R. philipii infection prevalence of 2.1% in adults, 0.9% in nymphs and a minimum infection prevalence of 0.4% in larval pools. Although most human cases of PCTF have been reported from northern California, acarological surveillance suggests that R. philipii may occur throughout the distribution range of D. occidentalis. |
- Page last reviewed:Feb 1, 2024
- Page last updated:May 13, 2024
- Content source:
- Powered by CDC PHGKB Infrastructure