Molecular Investigations of Rickettsia helvetica infection in dogs, foxes, humans, and Ixodes ticks.
نویسندگان
چکیده
Rickettsia helvetica, a tick-borne member of the spotted-fever-group rickettsiae, is a suspected pathogen in humans; however, its role in animals is unknown. The aims of this study were to establish a R. helvetica-specific real-time TaqMan PCR assay and apply it to the analysis of tick vectors (to determine potential exposure risk) and blood samples from Canidae and humans (to determine prevalence of infection). The newly designed 23S rRNA gene assay for R. helvetica was more sensitive than a published citrate synthase gene (gltA) assay for several rickettsiae. Blood samples from 884 dogs, 58 foxes, and 214 human patients and 2,073 ticks (Ixodes spp.) collected from either vegetation or animals were analyzed. Although the maximal likelihood estimate of prevalence was 12% in unfed ticks and 36% in ticks collected from animals, none of the 1,156 blood samples tested PCR positive. Ticks from cats were more frequently PCR positive than ticks from dogs. Sequencing of the 23S rRNA and/or the gltA gene of 17 tick pools confirmed the presence of R. helvetica. Additionally, Rickettsia monacensis, which has not been previously found in Switzerland, was identified. In conclusion, R. helvetica was frequently detected in the tick population but not in blood samples. Nevertheless, due to the broad host range of Ixodes ticks and the high rate of infestation with this agent (i.e., R. helvetica was 13 times more frequent in unfed ticks than the tick-borne encephalitis virus), many mammals may be exposed to R. helvetica. The PCR assay described here represents an important tool for studying this topic.
منابع مشابه
Evidence of Rickettsia helvetica infection in humans, eastern France.
A 37-year-old man living in eastern France seroconverted to Rickettsia helvetica in August 1997, 4 weeks after the onset of an unexplained febrile illness. Results of a serosurvey of forest workers from the area where the patient lived showed a 9.2% seroprevalence against R. helvetica. This organism may pose a threat for populations exposed to Ixodes ricinus ticks.
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ورودعنوان ژورنال:
- Applied and environmental microbiology
دوره 75 10 شماره
صفحات -
تاریخ انتشار 2009