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Introduction
In South Africa, a number of studies have been done on tick-borne diseases of canines targeting Ehrlichia canis, Babesia vogeli and Babesia rossi in host animals (Allsopp & McBride 2009; Matjila et al. 2008; McBride et al. 1996). However, full description of zoonotic pathogens such as Rickettsia species, Borrelia burgdorferi, Anaplasma phagocytophilum and Coxiella burnetii as well as their relationship to emerging and characterised illnesses, is not widely available. The widespread occurrence of tick hosts in South Africa may promote the occurrence of diseases caused by the above-mentioned pathogens as speculated by Fivaz and Petney (1989).
Ehrlichioses are very diverse, but the organisms causing infections in the country have yet to be isolated and characterised. Serological studies have shown that up to 75% of dogs have significant antibody titres against E. canis and Ehrlichia chaffeensis in Bloemfontein, South Africa (Pretorius & Kelly 1998). DNA of E. canis and that of a novel Ehrlichia species closely related to Ehrlichia ruminantium have been found in the blood of dogs in South Africa. These animals showed clinical signs suggestive of ehrlichiosis, but it could not be confirmed whether the E. ruminantium-like organism was the cause of the illness (Allsopp & Allsopp 2001; Inokuma et al. 2005; McBride et al. 1996).
Anaplasma phagocytophilum and B. burgdorferi sensu lato, the causative agents of human granulocytic anaplasmosis (HGA) and Lyme disease (LD), respectively, are common in North America and Europe (Liebisch, Sohns & Bautsch 1998; Maudlin, Eisler & Welburn 2009). Anecdotal cases of LD (Strijdom & Berk 1996) and a novel Anaplasma species closely related to A. phagocytophilum detected in canine blood in South Africa (Inokuma et al. 2005) have been described. Despite reports of these pathogens, their true incidence has not been properly investigated.
Rickettsioses caused by Rickettsia conorii (Mediterranean spotted fever [MSF]) and Rickettsia africae (African tick-bite fever [ATBF]) are the most common forms in sub-Saharan Africa. Although not commonly reported among indigenous people because they do not display clinical signs of the diseases (Kelly 2006; Ndip et al. 2004; Rutherford et al. 2004), they have proven to be problematic to South Africa’s tourism industry, where numerous reports of infection and illness have been reported from tourists returning to their home countries after visiting nature...