Sympatry of Amblyomma eburneum and Amblyomma variegatum on African buffaloes and prevalence of pathogens in ticks

Abstract

The Amblyomma genus is represented on the African continent by 24 species, out of which 17 are known to occur in different ecological niches of southern Africa. Amblyomma, known for their aggressive hunting behaviour and aptitude as pathogen vectors, are of main concern to travellers, mainly in rural and conservation areas of Africa. In this study, we highlight the overlapping distribution of Amblyomma eburneum and Amblyomma variegatum found on African buffaloes (Syncerus caffer) at Coutada 11, Central Mozambique. In total, 1,039 Amblyomma ticks were collected and morphologically identified using taxonomic keys, and genomic DNA was extracted. They were subjected to reverse line blotting for pathogen identification followed by molecular analysis (COI sequencing) of both tick species. Pathogens such as Ehrlichia ruminantium, Anaplasma centrale, Theileria sp., Babesia sp. and Rickettsia africae were detected, of which R. africae is zoonotic. Ehrlichia ruminantium, R. africae, Theileria mutans and Theileria velifera are well-established pathogens transmitted by Amblyomma ticks; however, Anaplasma spp. and Babesia spp. are not, suggesting residual parasite DNA in the bloodmeal. Little is mentioned in the literature about A. eburneum, including its role as a vector and reservoir for pathogens. In Mozambique A. eburneum is currently restricted to wildlife but the spread of the tick may be observed given the climate change that is occurring. The infection rates for the pathogens in both Amblyomma tick species were lower than expected, but this may be due to the low host density in the forest niche and the innate immunity of these hosts. With the propensity of ticks of the Amblyomma genus to form parapatric distributions, the mechanisms that allows for the overlapping distribution of these two Amblyomma species while maintaining tick species identity is of great interest.