Genetic diversity of Coxiella burnetii in ticks from the Republic of Guinea

Coxiella burnetii is a worldwide zoonotic pathogen responsible for Q fever. Ticks act as both potential reservoirs and vectors of C. burnetii, playing a critical role in maintaining its natural transmission cycle. Nevertheless, the vector competence of ticks in transmitting C. burnetii remains a topic of ongoing scientific debate. This study aims to investigate the genetic diversity of C. burnetii in ixodid ticks from the Republic of Guinea. Ixodid ticks were collected from cattle, goats, sheep, and dogs across eight locations of the Republic of Guinea in 2023. Ticks were identified to the species level using both morphological and molecular methods. Screening for C. burnetii was performed using two quantitative polymerase chain reaction assays targeting the IS1111 and IS30 sequences. Positive samples were subsequently genotyped using multispacer sequence typing (MST) with 10 spacer regions. A total of 946 ticks were collected screening revealed the presence of C. burnetii DNA in 5.4 % (52/946) of ticks. The main tick species positive for C. burnetii were Rhipicephalus sanguineus s.l. 19.2 % (10/52), Rhipicephalus microplus 17.3 % (9/52) and Hyalomma truncatum 13.4 % (7/52). Genotyping of 38.4 % (20/52) of the C. burnetii-positive specimens identified five different genotypes, including four novel ones (MST 86, MST 87, MST 88, and MST 89) and one previously described genotype, MST 61. Molecular identification of the 52 ticks positive for C. burnetii DNA revealed 12 tick species. This study underscores the Republic of Guinea as a hotspot for C. burnetii genetic diversity, with novel genotypes suggesting localized evolution or cross-species transmission.