ABSTRACT:Eight ixodid tick species, associated with 59 free-ranging mammals belonging to 10 species, were collected at five different localities in the Free State Province, South Africa. Four of the study areas were nature reserves (Willem Pretorius, Sandveld, Tussen-die-Riviere, and Soetdoring), and one site was a private farm located in Senekal district. The collection was performed from March 2006 until June 2006. Ticks (n5569) and tissues from animals (n552) were analyzed by polymerase chain reaction, reverse line blot, and sequencing for various tickborne pathogens belonging to the genera Babesia, Theileria, Anaplasma, and Ehrlichia. Rhipicephalus (Boophilus) microplus, the known vector of Babesia bovis responsible for Asiatic redwater in South Africa, was found for the first time in the Free State Province. Rhipicephalus appendiculatus also was collected in areas in the Free State where it has not been previously described. Anaplasma marginale was detected for the first time in a gemsbok (Oryx gazella gazella). Gene sequences recovered in this study were 98-100% homologous with GenBank sequences for Anaplasma bovis, Theileria separata, and Theileria sp. Malelane sable antelope.

Infestations with ticks have an important economic impact on the cattle industry worldwide and resistance to acaricides has become a widespread phenomenon. To optimize their treatment strategy, farmers need to know if and against which classes potential acaricide-resistance does occur. Bioassays are used to assess the resistance level and pattern of Rhipicephalus (Boophilus) microplus populations. The objective of the current study was to assess the susceptibility of Þeld populations originating from Argentina (8), South Africa (3), and Australia (2) using the Larval Tarsal Test. Nine acaricidal compounds from Þve major classes were tested: organosphosphates, synthetic pyrethroids (SP), macrocyclic lactones, phenylpyrazols, and amidines. The resistance ratios at concentrations inducing 50 and 90% mortality were used to detect established and emerging resistance. This study conÞrmed the newly reported presence of amitraz resistance in populations from Argentina. In addition, resistance to SP appeared to be widespread (88%) in the Argentinean farms, which had been selected based on the observation of lack of treatment efÞcacy by farmers. In South Africa one of the three populations was found to be resistant to SP and to a phenylpyrazol compound (pyriprol). Furthermore, resistance to organosphosphates and SP was observed in Australia. Finally, the Larval Tarsal Test proved to be a suitable test to evaluate the susceptibility of R. microplus Þeld populations to the most relevant acaricidal classes.RESUMEN Las infestaciones por garrapatas tienen un importante impacto económico en la industria del ganado de todo el mundo y la resistencia a los acaricidas se ha convertido en un fenómeno generalizado. Con el Þn de optimizar la estrategia de los tratamientos, los ganaderos necesitan saber en contra de cuáles clases de acaricidas ocurre esa potencial resistencia. Se utilizan bioensayos para evaluar el patrón y nivel de resistencia de Rhipicephalus (Boophilus) microplus. El objetivo del presente estudio fue evaluar la susceptibilidad de poblaciones de campo procedentes de Argentina (8), Sudáfrica (3) y Australia (2) usando la prueba del tarso de las larvas (LTT). Nueve compuestos acaricidas de cinco clases principales: organofosforados (OP), piretroides sintéticos (SP), lactonas macrocṍclicas (ML), fenilpirazoles (PYZ) y amidinas. Para detectar resistencia establecida y emergente, se calcularon niveles de resistencia basados en concentraciones que inducen mortalidad a 50% y 90%. Este estudio conÞrma la nueva denuncia de la presencia de resistencia al amitraz en las poblaciones de garrapatas de Argentina. Además, la resistencia a SP parece estar muy difundida (88%) en los establecimientos argentinos, seleccionados sobre la base de la observación de los ganaderos, de la falta de eÞcacia de los tratamientos. En Sudáfrica, en una de las tres poblaciones, se encontró que era resistente a SP y a un compuesto PYZ (pyriprol). Además, resistencia a OP y SP fue observada en Australia. Finalmente, la LTT ha demostrado ser un...

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A total of 7364 ticks belonging to 13 species was collected from 64 game animals (belonging to 11 species) and from 64 livestock animals (cattle and sheep) living in close vicinity at 6 localities in 3 South African Provinces (Free State, Mpumalanga, and Limpopo). The geographic distribution of all tick species was congruent with the literature except for Haemaphysalis silacea. From each infested host, a maximum of 10 males and 10 females of each tick species were dissected to isolate the salivary glands. Salivary glands were screened for tick-borne pathogens using polymerase chain reaction followed by reverse line blotting and sequencing. This approach allowed us to evaluate the exposure of wild and domestic hosts to tick-borne pathogens in their respective environments. Among the 2117 examined ticks, 329 (15.5%), belonging to 8 species, were infected and harboured 397 infections. Among those, 57.7% were identified to species level and were assigned to 23 pathogen species of the genera Babesia, Theileria, Anaplasma, and Ehrlichia. In 3 out of 6 localities, salivary glands from ticks infesting wild ruminants displayed significantly higher infection prevalence and pathogen mean density than salivary glands from ticks infesting livestock animals. Four piroplasm species [Theileria bicornis, Babesia sp. (sable), Theileria sp. (giraffe), and Theileria sp. (kudu)] were detected for the first time in ticks. The tick species Rhipicephalus evertsi evertsi, Rhipicephalus (Boophilus) decoloratus, Hyalomma rufipes, Rhipicephalus appendiculatus, and Amblyomma hebraeum were associated with a broader pathogen range than previously known, and thus new vector-pathogen combinations are described. In addition, previously unknown coinfection patterns in tick salivary glands are reported.