Pathogens, endosymbionts, and blood-meal sources of host-seeking ticks in the fast-changing Maasai Mara wildlife ecosystem

Background: The role of questing ticks in the epidemiology of tick-borne diseases in Kenya9s Maasai Mara National Reserve (MMNR), an ecosystem with intensified human-wildlife-livestock interactions, remains poorly understood. Therefore, we carried out a survey of the diversity of questing ticks, their blood-meal hosts, and tick-borne pathogens to understand potential effects to human and livestock health.  Methods: Questing ticks were collected by flagging and hand picks from vegetation in 25 localities and identified based on morphologic and molecular criteria. We used PCR with high-resolution melting (HRM) analysis, and sequencingto identify  Anaplasma, Babesia, Coxiella, Ehrlichia, Rickettsia, and  Theileria  pathogen diversities and blood meals in 231 tick pools. Results:  A total of 1,465 host-seeking ticks were collected, including  Rhipicephalus appendiculatus  (n = 1,125),  Rhipicephalus pulchellus  (n = 6),  Rhipicephalus evertsi  (n = 5),  Amblyomma  cf.  gemma  (n = 178),  Amblyomma gemma  (n = 145),  Amblyomma variegatum (n = 4),  Amblyomma  sp . (n = 1), and  Haemaphysalis leachi  (n = 1). Remnant blood-meals from humans, wildebeest, and African buffalo were detected in Rh. appendiculatus ,goat in  Rh. evertsi , sheep in  Am. gemma , and cattle in  Am. variegatum .  Rickettsia africae  was detected in  Am. gemma  (1/25 pools)that had blood-meal remnant from sheep and  Am. variegatum  (4/25 pools) that had fed on cattle. Rickettsia  spp. were found in  Am. gemma  (4/25 pools) and Rh. evertsi  (1/4 pools).  A naplasma ovis  was detected in  Rh. appendiculatus (1/172 pools) and  Rh. evertsi  (1/4 pools), while  A naplasma bovis  wasdetected in  Rh. appendiculatus (1/172 pools).  Theileria parva  was detected in  Rh. appendiculatus (27/172 pools).   Babesia, Ehrlichia and  Coxiella  pathogens were not found in any ticks. Unexpectedly, diverse  Coxiella sp. endosymbionts were detected in all tick genera (174/231 pools). Conclusions : The data shows that ticks from the rapidly-changing MMNR are infected with zoonotic R.africae and unclassified Rickettsia spp, demonstrating the persistent risk of African tick-bite fever and other and Spotted Fever Group rickettsioses to local dwellers and visitors to the Maasai Mara ecosystem. Protozoan pathogens that may pose risk to livestock production were also identified. We also highlight possible existence of morphotypic variants of Amblyomma species, based on the observation of Ambyomma cf . gemma , which may be potential human parasites or emergent disease vectors. Our findings also demonstrate that questing ticks in this ecosystem have dynamic vertebrate blood sources including humans, wildlife and domestic animals, which may amplify transmission of tickborne zoonoses and livestock diseases. Further studies are needed to determine the role of Coxiella endosymbionts in tick physiology and vector competence.