Rickettsia africae and Rickettsia massiliae in ixodid ticks infesting small ruminants in agro-pastoral settlements in Plateau State, Nigeria

Arthropods, especially ixodid ticks, have been incriminated in the epidemiology of Spotted Fever Group rickettsioses globally leading to an increasing spectrum of emerging and re-emerging zoonoses with attendant consequences on trade and tourism. The objective of this study was to determine the role of ixodid ticks infesting small ruminants in Plateau State, Nigeria, in the epidemiology of Spotted Fever Group Rickettsiae (SFGR) in the study area. DNA from 130 out of 323 ixodid ticks collected from 179 goats and 121 sheep owned by agro-pastoralists in Plateau State were screened for the evidence of SFGR by molecular methods. Six tick species from four genera were identified: Amblyomma, Hyalomma, Rhipicephalus (Boophilus) and Rhipicephalus. Rhipicephalus sanguineus sensu lato (s.l.) was the predominant (54.5%) species among collected ticks. Tick infestation was significantly associated with the species of small ruminants, the sex of the animals and the sampling locations except for Jos South. Conventional PCR targeting the 381 bp of the citrate synthase (gltA) and 820 bp of the outer membrane protein B (ompB) genes detected DNA of SFGR in nine and eight samples, respectively. Sequence analysis revealed that five sequences obtained from Amblyomma variegatum were 99–100% identical to Rickettsia africae and three sequences from Rh. sanguineus (s.l.) were 100% identical to Rickettsia massiliae reported from Spain. To our knowledge, this is the first report of the detection of R. africae DNA in Am. variegatum collected from small ruminants in Plateau State. Ixodid ticks infesting small ruminants in Plateau state harbor DNA of SFGR with potential veterinary and public health implications.