COMPARISON OF A CONVENTIONAL PCR AND TWO FIELD-FRIENDLY TESTS TO DETECT COXIELLA BURNETII DNA IN TICKS USING BAYESIAN LATENT CLASS ANALYSIS.

Livestock and wildlife infected with Coxiella burnetii have been epidemiologically linked to human Q fever outbreaks. Despite this growing zoonotic threat, knowledge of coxiellosis in wildlife species remains limited, and new techniques to aid understanding of their epidemiologic role are needed. In C. burnetii-endemic areas, ticks have been reported to harbor and spread C. burnetii, and hence can serve as indicators of infection burden. This study compared molecular techniques for detecting C. burnetii in ticks and to determine its prevalence in a wildlife area. We screened 179 ticks collected from wildlife and cattle in wildlife conservancies in Northern Kenya for C. burnetii DNA. We compared results from a conventional PCR (cPCR) and two field-friendly techniques: Biomeme’s C. burnetii RT-PCR Go-strips (Biomeme) and a new C. burnetii PCR high-resolution melting (PCR-HRM) analysis assay. We applied a one population, Bayesian latent class analysis (BLCA) to estimate the C. burnetii prevalence and determine diagnostic sensitivity (DSe) and specificity (DSp) of the three tests. The final BLCA model was chosen based on model fit, which included main effects and accounted for covariances between some of the assays. Our model estimated that PCR-HRM had the highest DSe (86%; 95% credible interval: 56–99%), followed by the Biomeme (DSe=70%; 95% credible interval: 38-98%). The estimated DSe of the cPCR was lower (18%, 95% credible interval: 3-51%). Diagnostic specificity estimates for all three assays ranged from 91-97%. The C. burnetii prevalence estimate in the tick samples was 14% (95% credible interval: 6.4-26%). Our results highlight the endemicity of C. burnetii in Northern Kenya and provide new data on diagnostic test performance using field-appropriate methods for C. burnetii surveillance in ticks. Our findings contribute to a better understanding of C. burnetii in wildlife and enhance future C. burnetii surveillance efforts.