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The tortoise tick Amblyomma marmoreum was collected from large numbers of reptiles and other animals during the course of numerous surveys conducted in South Africa. A total of 1 229 ticks, of which 550 were adults, were recovered from 309 reptiles belonging to 13 species, with leopard tortoises, Geochelone pardalis being the most heavily infested. The 269 birds sampled harboured 4 901 larvae, 217 nymphs and no adult ticks, and the prevalence of infestation was greatest on hel meted guinea fowls, Numida meleagris. Only two larvae were recovered from 610 rodents, including 31 spring hares, Pedetes capensis, whereas 1 144 other small mammals yielded 1 835 immature ticks, of which 1 655 were collected from 623 scrub hares, Lepus saxatilis. The 213 carnivores examined harboured 2 459 ticks of which none were adult. A single adult tick and 6 684 larvae and 62 nymphs were recovered from 656 large herbivores, and a total of 4 081 immature ticks and three adults were collected from 1 543 domestic animals and 194 humans. Adult male and female A. marmoreum were most numerous on reptiles during January and February, and larvae during March. The largest numbers of larvae were present on domestic cattle and helmeted guineafowls in the Eastern Cape Province during March or April respectively, whereas larvae were most numerous on helmeted guineafowls, scrub hares and the vegetation in north-eastern Mpumalanga Province during May. In both provinces nymphs were most numerous between October and December. Amblyomma marmoreum appears to be most prevalent in the western regions of the Western and Eastern Cape and Free State provinces, and the north-eastern regions of the Northern Cape, KwaZulu- Natal, Mpumulanga and Limpopo provinces.

Ticks, as vectors of disease and damage agents, impact directly and indirectly on the economy of the livestock industry in southern Africa. This study surveyed the occurrence and distribution of ticks infesting livestock across the North West province, South Africa. During three phases in consecutive years, officers of the provincial Veterinary Department collected specimens monthly from livestock hosts at specified sites across the province. Data analysis constituted the fourth phase of the study. A total of 1090 collections from 265 sites yielded 42 566 tick specimens, comprising 22 different tick species (18 ixodids, 4 argasids). The specimens represent all of the major tick vectors of disease that occur in South Africa. The major tick-borne diseases (i.e. heartwater, both African and Asiatic bovine babesiosis and anaplasmosis) were found to be prevalent mainly in the north-eastern region of the province, which also displayed the highest tick species diversity. The central region appears transitory to some of the major vectors. Although some tick species were contained within specific regions, others were widespread across the province. Associated serology data show that most herds sampled in areas endemic for babesiosis and anaplasmosis in the north-eastern region are endemically unstable and at risk to these tick-borne diseases should vector control measures become ineffective.

Bovine anaplasmosis, caused by the tick-borne rickettsia Anaplasma marginale, is endemic in South Africa and results in considerable economic loss to the cattle industry. This study was designed to characterize strains of A. marginale at the molecular level from cattle raised in communal and commercial farms in the north-eastern and south-western regions of the Free State Province, South Africa, that varied in rainfall and vegetation. Seroprevalence to A. marginale was determined in 755 cattle by an Anaplasma spp. competitive enzyme-linked immunosorbent assay and ranged from 44% to 98% and was similar in both regions. While Anaplasma centrale was not targeted in this study, A. marginale infections were identified by species-specific msp1alpha polymerase chain reaction in 129 of 215 of the samples studied. Similar genetic diversity of A. marginale strains was found in both the north-eastern and south-western regions. The sequences of 29 A. marginalemsp1alpha amplicons from South African strains revealed considerable genetic diversity providing 14 new repeat sequences. However, 42% of MSP1a repeat sequences were not unique to this region. These results indicated the presence of common genotypes between South African, American and European strains of A. marginale. Cattle movement between different parts of South Africa was suggested by the presence of identical A. marginale MSP1a genotypes in north-eastern and south-western regions of the Free State Province. Control strategies for anaplasmosis in South Africa should therefore be designed to be protective against genetically heterogeneous strains of A. marginale.