Comparison of test performance of a conventional PCR and two field-friendly tests to detect Coxiella burnetii DNA in ticks using Bayesian latent class analysis

Maureen W Kamau; Carmel Witte; Wynand Goosen; Mathew Mutinda; Jandouwe Villinger; Dennis Getange; Rua Khogali; Michael E von Fricken; Eric Maurice Fèvre; Dawn Zimmerman; Yvonne-Marie Linton; Michele Miller

doi:10.3389/fvets.2024.1396714

Comparison of test performance of a conventional PCR and two field-friendly tests to detect Coxiella burnetii DNA in ticks using Bayesian latent class analysis

Front Vet Sci. 2024 Jun 19:11:1396714. doi: 10.3389/fvets.2024.1396714. eCollection 2024.

Authors

Maureen W Kamau^{1

2

3}, Carmel Witte^{2

4}, Wynand Goosen², Mathew Mutinda⁵, Jandouwe Villinger⁶, Dennis Getange⁶, Rua Khogali⁶, Michael E von Fricken⁷, Eric Maurice Fèvre^{8

9}, Dawn Zimmerman¹⁰, Yvonne-Marie Linton^{11

12

13}, Michele Miller²

Affiliations

¹ Mpala Research Centre, Nanyuki, Kenya.
² Division of Molecular Biology and Human Genetics, Department of Science, and Innovation - National Research Foundation Centre of Excellence for Biomedical Tuberculosis Research, Faculty of Medicine and Health Sciences, South African Medical Research Council Centre for Tuberculosis Research, Stellenbosch University, Stellenbosch, South Africa.
³ Global Health Program, Smithsonian National Zoo Conservation Biology Institute, Washington, DC, United States.
⁴ The Center for Wildlife Studies, South Freeport, ME, United States.
⁵ Kenya Wildlife Service, Nairobi, Kenya.
⁶ International Centre of Insect Physiology and Ecology (ICIPE), Nairobi, Kenya.
⁷ College of Public Health and Health Professionals, Department of Environmental and Global Health University of Florida, Gainesville, FL, United States.
⁸ International Livestock Research Institute, Nairobi, Kenya.
⁹ Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom.
¹⁰ Veterinary Initiative for Endangered Wildlife, Bozeman, MT, United States.
¹¹ Walter Reed Biosystematics Unit (WRBU) Smithsonian Institution Museum Support Center, Suitland, MD, United States.
¹² One Health Branch, Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, United States.
¹³ Department of Entomology, Smithsonian Institution, National Museum of Natural History (NMNH), Washington, DC, United States.

Abstract

Introduction: Coxiella burnetii (C. burnetii)-infected livestock and wildlife have been epidemiologically linked to human Q fever outbreaks. Despite this growing zoonotic threat, knowledge of coxiellosis in wild animals remains limited, and studies to understand their epidemiologic role are needed. In C. burnetii-endemic areas, ticks have been reported to harbor and spread C. burnetii and may serve as indicators of risk of infection in wild animal habitats. Therefore, the aim of this study was to compare molecular techniques for detecting C. burnetii DNA in ticks.

Methods: In total, 169 ticks from wild animals and cattle in wildlife conservancies in northern Kenya were screened for C. burnetii DNA using a conventional PCR (cPCR) and two field-friendly techniques: Biomeme's C. burnetii qPCR Go-strips (Biomeme) and a new C. burnetii PCR high-resolution melt (PCR-HRM) analysis assay. Results were evaluated, in the absence of a gold standard test, using Bayesian latent class analysis (BLCA) to characterize the proportion of C. burnetii positive ticks and estimate sensitivity (Se) and specificity (Sp) of the three tests.

Results: The final BLCA model included main effects and estimated that PCR-HRM had the highest Se (86%; 95% credible interval: 56-99%), followed by the Biomeme (Se = 57%; 95% credible interval: 34-90%), with the estimated Se of the cPCR being the lowest (24%, 95% credible interval: 10-47%). Specificity estimates for all three assays ranged from 94 to 98%. Based on the model, an estimated 16% of ticks had C. burnetii DNA present.

Discussion: These results reflect the endemicity of C. burnetii in northern Kenya and show the promise of the PCR-HRM assay for C. burnetii surveillance in ticks. Further studies using ticks and wild animal samples will enhance understanding of the epidemiological role of ticks in Q fever.

Keywords: Coxiella burnetii; Q fever; diagnostics; sensitivity; specificity; ticks; wildlife.

Grants and funding

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. MK received support from the EcoHealth Alliance’s 2021 EcoHealthNet research exchange and virtual workshop themed, “Navigating the Age of Pandemics.” MMi and WG were partially supported by the South African government through the South African Medical Research Council; the National Research Foundation South African Research Chair Initiative (Grant #86949); and Wellcome Trust (grant number 222941/Z/21/Z). This work was also partially supported by the PrePARE4VBD project, funded by the European Union’s Horizon 2020 research and innovation program (European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program; Euratom research and training program 2019–2020) under grant agreement No. 101000365. RK received additional support from the German Academic Exchange Service (DAAD) through the icipe ARPPIS-DAAD scholarship and through a UP post-graduate bursary. We also acknowledge icipe institutional funding from the Swedish International Development Cooperation Agency (SIDA), the Swiss Agency for Development and Cooperation (SDC), the Federal Democratic Republic of Ethiopia, and the Government of the Republic of Kenya. MK and Y-ML were partially supported by the US Army Medical Research and Development Command under Contract No. W81XWH-21-C-0001, W81XWH-22-C-0093, and HT9425-23-C-0059. The Armed Forces Health Surveillance Division (AFHSD), Global Emerging Infections Surveillance (GEIS) branch also provided funding support for this work (ProMIS ID # P0053_24_WR). Material has been reviewed by the Walter Reed Army Institute of Research. There is no objection to its presentation and/or publication. The opinions or assertions contained herein are the private views of the author(s), and are not to be construed as official, or as reflecting true views of the Department of the Army or the Department of Defense, or any of the other funders.