Molecular Detection and Characterization of Rickettsia Species in Ixodid Ticks Collected From Cattle in Southern Zambia

Abstract

Tick-borne zoonotic pathogens are increasingly becoming important across the world. In sub-Saharan Africa, tick-borne pathogens identified include viruses, bacteria and protozoa, with <i>Rickettsia</i> being the most frequently reported. This study was conducted to screen and identify <i>Rickettsia</i> species in ticks (Family <i>Ixodidae</i>) infesting livestock in selected districts of southern Zambia. A total of 236 ticks from three different genera (<i>Amblyomma, Hyalomma</i>, and <i>Rhipicephalus</i>) were collected over 14 months (May 2018-July 2019) and were subsequently screened for the presence of <i>Rickettsia</i> pathogens based on PCR amplification targeting the outer membrane protein B (<i>ompB</i>). An overall <i>Rickettsia</i> prevalence of 18.6% (44/236) was recorded. Multi-locus sequencing and phylogenetic characterization based on the <i>ompB, ompA</i>, 16S <i>rRNA</i> and citrate synthase (<i>gltA</i>) genes revealed the presence of <i>Rickettsia africae</i> (<i>R. africae</i>), <i>R. aeschlimannii</i>-like species and unidentified <i>Rickettsia</i> species. While <i>R. aeschlimannii</i>-like species are being reported for the first time in Zambia, <i>R. africae</i> has been reported previously, with our results showing a wider distribution of the bacteria in the country. Our study reveals the potential risk of human infection by zoonotic <i>Rickettsia</i> species and highlights the need for increased awareness of these infections in Zambia's public health systems.