Identification of tick species and their bacterial pathogens from cattle in two provinces of South Africa

Abstract

In South Africa, resource-poor farmers are negatively affected by death and ill health

of livestock due to high tick infestations. Tick infestations are associated with tick- borne pathogens causing various diseases that are a major constraint to cattle

farming, a threat to human health and consequently the economy. This has been an ongoing concern for resource-poor farmers, mostly influenced by the inability to access veterinary care or proper education on the usage of veterinary products. This study sought to investigate the presence of ticks and their associated pathogens at three study sites, namely Harrismith and Phuthaditjhaba in the Free State province as well as Bergville in KwaZulu Natal. These are three neighbouring towns, where the point of intersection for livestock is the Drakensberg Mountains, which serve as a source of vegetation for grazing livestock. Between these three study sites there is uncontrolled translocation of livestock due to traditional practices and trade and thus the introduction of several tick species. Ticks are recognised worldwide as major vectors of several disease-causing pathogens and are good indicators of pathogen distribution and epidemiology. However, global warming has result in climate change and consequently expanded tick distribution. Consequently, growing incidences of emerging and re-emerging tick- borne pathogens capable of causing tick-borne diseases (TBDs) of veterinary and economic importance. These TBDs are major hindrances that constrain cattle farming,

thus culminating in significant losses: threatening food security, global trade, eco- tourism, and affecting human and livestock health. Therefore, this study sought to identify ticks and detect bacterial tick-borne pathogens in the three neighbouring towns: Harrismith, Phuthaditjhaba and Bergville using a 16S rRNA next-generation sequencing (NGS) approach based on the PacBio sequencing platform. A total of n=50 blood samples were collected from cattle in each study site and n=418 ticks were collected from these cattle, comprising n=126 ticks from Harrismith, n=160 from Phuthaditjhaba and n=132 from Bergville. Ticks infesting cattle were identified morphologically to belong to the genera Rhipicephalus with six species and Hyalomma with only two species. Harrismith had Rhipicephalus decoloratus, R. microplus, R. evertsi evertsi, Hyalomma truncatum, H. rufipes, Phuthaditjhaba: R. appendiculatus R. simus, R. evertsi evertsi, R. afranicus, H. rufipes and Bergville: R. evertsi evertsi, R. appendiculatus, H. truncatum. Out of n=418 ticks collected, R. evertsi evertsi with n=332 was the most dominant tick species in the three study sites, whereas R. decoloratus and R. microplus tick species were only present in Harrismith. A full-length 16S rRNA gene was amplified and sequenced using PacBio technology for the identification of bacterial pathogens associated with these ticks. A total of 7,687,581 reads were obtained. Bacterial pathogens identified belonged to the genera Anaplasma, Mycoplasma and Ehrlichia. Anaplasma species detected were A. marginale, A. centrale, A. phagocytophilum, A. platys and A. bovis. Mycoplasma species were M. wenyonii and M. bovis. Ehrlichia species detected were E. ruminantium and E. canis. Anaplasma marginale, with a relative abundance of 43.5% in Harrismith, 54.2% in Phuthaditjhaba and 56.2% in Bergville, was the most abundant, followed by A. platys with 31.5% in Harrismith, 32.9% in Phuthaditjhaba and 22.6% in Bergville. Mycoplamsa wenyonii was 19.6% Harrismith, 7.8% in Phuthadijthaba and 14% in Bergville. The bacterial composition at the three sites aligned with the tick vectors identified at the three-study sites. The presence of R. microplus and R. decoloratus was reported for the first time in Harrismith, while R. turanicus was identified for the first time in Phuthaditjhaba. This shows that there has been an expansion in tick distribution because of climate change and possibly other ecological and anthropogenic factors.