In vivo evidence for the resistance of Theileria annulata to buparvaquone
2010
Mhadhbi, Moez | Naouach, Abdelkarim | Boumiza, Aïssa | Chaabani, Mohamed Faouzi | BenAbderazzak, Souha | Darghouth, Mohamed Aziz
The present study describes an outbreak of tropical theileriosis cases refractory to buparvaquone treatment, which occurred in a small-size dairy farm in Tunisia. Out of seven treated cows, four died in spite of repeated buparvaquone injections (2.5 and 5mgkg⁻¹) and the monitoring of the affected cows showed no improvement of the course of the disease with a consistent decrease in the haematocrit, the persistence of fever and an increased parasitaemia after treatment. Ticks were fed on a calf experimentally infected with one isolate established in culture from one of the cases and the resultant infected ticks ground up to generate a supernatant infected with the potentially resistant stock. This was used to experimentally infect three calves, and the clinical observations, post-buparvaquone treatment, showed an absence of the usual effect of buparvaquone treatment on the parasite Theileria annulata, such as the rapid decline of schizont index and parasitaemia and a rapid recovery from the disease. These results confirmed for the first time the occurrence of resistance to buparvaquone in the protozoan T. annulata.
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