INTRODUCTION
Tick-borne pathogens have been identified as the etiologic agents of emerging important human diseases especially in many tropical countries in Africa, Asia and South America (Parola et al., 2013). In many sub-Saharan Africa countries, these diseases are rampant in rural communities where there are frequent contacts between humans and domestic animals that are hosts to these ticks (Parola et al., 2013; Raoult and Roux, 1997). Rickettsioses are zoonotic diseases that are caused by some pathogenic Rickettsia spp. They are one of the oldest known vector-borne zoonotic diseases whose severity varies from one etiologic agent to another. There are many recognized species ofRickettsia that are delineated into four major groups namely; the typhus group consisting of two species which are R.typhi andR.prowazekii, the spotted fever group which contains many species that are wholly transmitted to humans through ticks bite, the transitional group comprising of R.australisR. akari  and R.felis that are associated with ticks, mites and fleas and the ancestral group made up of R.bellii and R.canadensis . Beside these groups, there are also many otherRickettsia species that do exist but have not been fully characterized (Raoult and Roux, 1997; Bogovic et al., 2016). The current guidelines for the classification, delineation and description of novel rickettsial isolates are based on the 16S rRNA gene, the differences in nucleotide sequence of glt A, omp A, omp B, and the D genes that encodes for essential proteins in the organisms ( Portillo et al., 2017). The global distribution of tick-borne rickettsioses varies from one region to the other as their geographical spread are determined by their ticks vectors whose distributions are generally governed by suitable environmental conditions like relative temperatures, humidity and biotopes which varies from one region to the other (Socolovschi et al., 2009; Tomassone et al., 2018).
Members of the genera Amblyomma, Hyalomma, Rhipicephalus, Ixodes, Dermacentor and Haemaphysalis are the species of tick that are generally involved in the transmission of tick-borne rickettsioses in the tropical regions of the world. Transmission of tick-borne rickettsioses could be either transstadial or transovarial transmission thus making some tick species such as Amblyomma to be a known reservoir of R. africae (Tomassone et al., 2018). In the Eastern Cape of South Africa, the most common species of ticks are members of the genera; - Amblyomma, Rhipicephalus, Haemaphysalis, andHyalomma (Iweriebor et al., 2017; Yawa et al., 2019) and all these ticks’ genera have the ability to transmit one or multitudes of zoonotic pathogens. While most tick-borne pathogens are linked to known tick vectors, it is possible in some cases for an etiologic agent of a particular disease to be indeterminate.
Members of the SFG of the genus Rickettsia are the etiologic agents of tick-borne rickettsioses a group of diseases that its ticks vectors and clinical severity varies from one geographic location to another (Tomassone et al., 2018). The epidemiological and clinical attributes of tick-borne diseases are tied to the ecology and biotopes of their tick vectors (Tomassone et al., 2018) as each of these diseases are confined to different geographical regions though their distribution and redistribution keep varying overtime as well as the species of ticks that transmit them. Prior to the development of molecular approaches which are highly selective and sensitive in disease diagnoses, severalRickettsia spp. had been detected in ticks but their roles in the etiology of disease in humans were unrecognized. However, in recent times such species that were previously thought innocuous have now been directly linked to the etiology of human diseases (Parola et al., 2005; Bogovic et al., 2016).
The Eastern Cape of South Africa is predominantly rural with intensive animal husbandry where the animals are kept in close proximity to homes. Couple with this is that there are many game reserves where these animals are in close contact with those in the wild. There exist great possibilities of these domesticated animals being infested with ticks from those originating from the wild thus making the spread of zoonotic pathogens possible in these localities. Also, with the very high prevalence of HIV/AIDS in these rural communities, the chances of these immunocompromised patients coming down with zoonotic infections are equally very probable as they lack the competent immune system that ordinarily fights off these infections in healthy folks. Besides, most of the SFGR infections present with symptoms that are very much similar to flu and could thus be misdiagnosed by clinicians who might not consider them as top priority in diagnoses and treatments due to lack of laboratory diagnosis prior to commencement of treatments. This study therefore, was aimed at epidemiological surveillance for tick-borneRickettsia pathogens in ticks collected from domesticated animals in communities which are close to natural game reserves and human habitations in order to assess the likelihood of zoonotic diseases in humans who might be infested with ticks.