Atividade anti-helmíntica do Cambendazole, Mebendazole e Parbendazole, em uma estirpe de Haemonchus contortus resistente ao Thiabendazole, em ovinos

Resumo

Em ovinos livres de vermes e experimentalmente infestados com cinco mil larvas de Haemonchus contortus resistente ao thiabendazole (estirpe Uruguaiana), foi realizado um teste comparativo da atividade anti-helmíntica: 1) do cambendazole na dose de 20 mg/kg; 2) do mebendazole na dose de 12,5 mg/kg e 3) do parbendazole na dose de 15 mg/kg. Este teste foi relacionado com um grupo tratado com thiabendazole na dose de 44 mg/kg e com um grupo controle. Nas doses empregadas, os resultados obtidos demonstraram que:
1) o cambendazole, o mebendazole e o parbendazole apresentaram, respectivamente, 63,9, 76,0 e 95,4% de eficácia na estirpe Uruguaiana. Consequentemente ela é resistente ao cambendazole e ao mebendazole.
2) O thiabendazole, embora sem atividade anti-helmíntica sobre a estirpe Uruguaiana, demonstrou uma ação inibidora e esterilizante na oviposição. O parbendazole e o mebendazole demonstraram somente ação esterilizante. O cambendazole não demonstrou nenhuma dessas ações. Abstract Parasite free lambs were experimentally infected with 5.000 thiabendazole resistant Haemonchus contortus larvae (Uruguaiana strain). Subsequently, a controlled test of the anthelmintic activity on three groups of the animals were carried out using three drugs: 1) cambendazole at 20mg/Kg 2) mebendazole at 12,5 mg/Kg 3) parbendazole at 15 mg/Kg. Concomitantly, a fourth group sheep was treated with thiabendazole at 44 mg/Kg and a fifth group was untreated; both these group were used as control. The experimentation does permit to draw two conclusions. They are: first - on adults worms - cambendazole, mebendazole and parbendazole presented 63,9, 76,0 and 95,4% respectively, of efficacy. Consequently there was resistant against cambendazole and mebendazole.
Second - On worm’s eggs – although thiabendazole has no anthelmintic activity against the adults worms of this strain it inhibits the oviposition and sterilizes the eggs; but cambendazole does not present any action on the oviposition and no sterilization of the worm’s eggs to.