In vivo evidence for the resistance of Theileria annulata to buparvaquone.
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 5 mg kg(-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.
Mhadhbi
Moez
M
Laboratoire de Parasitologie, Ecole Nationale de Médecine Vétérinaire, 2020 Sidi Thabet, Tunisia.
Naouach
Abdelkarim
A
Boumiza
Aïssa
A
Chaabani
Mohamed Faouzi
MF
BenAbderazzak
Souha
S
Darghouth
Mohamed Aziz
MA
D000818:Animals; D000981:Antiprotozoal Agents / Q000627:therapeutic use*; D002417:Cattle; D003612:Dairying; D004196:Disease Outbreaks / Q000517:prevention & control / Q000662:veterinary; D004351:Drug Resistance; D006400:Hematocrit; D009285:Naphthoquinones / Q000627:therapeutic use*; D018512:Parasitemia / Q000188:drug therapy / Q000662:veterinary; D052939:Schizonts / Q000187:drug effects; D016796:Theileria annulata / Q000187:drug effects*; D013801:Theileriasis / Q000188:drug therapy*; D017211:Treatment Failure; D014416:Tunisia
D000981:Antiprotozoal Agents; D009285:Naphthoquinones; C046326:buparvaquone