Quantitative polymerase chain reaction from malaria rapid diagnostic tests to detect Borrelia crocidurae in Mali.

BACKGROUND: Tick-borne relapsing fever (TBRF) is caused by Borrelia species transmitted to humans by soft ticks of the genus Ornithodoros. Very little is currently known about the morbidity of this disease in Mali, despite the risk of human co-infection with malaria. The lack of appropriate diagnostic services or technical expertise to differentiate suspected malaria from other causes of febrile illness of unknown origin means that this tick-borne disease remains neglected and under-diagnosed in febrile patients in Mali. Our study investigated the detection of Borrelia crocidurae DNA in febrile patients in Mali from malaria rapid diagnostic tests (RDTs) for Plasmodium falciparum. METHODOLOGY/PRINCIPAL FINDINGS: Between June and December 2021, negative and positive malaria RDTs were collected from 41 health centers in the nine regions of Mali. Both qPCR and standard PCR were used to detect the presence of B. crocidurae DNA. RESULTS: Of the 1,496, malaria RDTs tested, B. crocidurae DNA was detected in 9 DNA extracts from malaria-negative RDTs. All of these were collected in the region of Kayes, where the prevalence rate was 5% (9/180) of the malaria RDTs. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that tick-borne relapsing fever is an under-diagnosed condition in Mali.