RHIPICEPHALUS (BOOPHILUS) MICROPLUS RESISTANCE AGAINST IVERMECTIN (200 MCG/KG AND 500 MCG/KG) IN NATURALLY INFESTED CATTLE
Autor(es): Breno Cayeiro Cruz, Carolina Buzzulini, Lucas Vinicius Costa Gomes, Vando Edésio Soares, Weslen Fabrício Pires Teixeira, Willian Giquelin Maciel, Luciana Prando, Gustavo Felippelli, Flávia Carolina Fávero, Murio Abud Bichuette, Gilson Pereira de Oliveira
RHIPICEPHALUS (BOOPHILUS) MICROPLUS RESISTANCE AGAINST IVERMECTIN (200 MCG/KG AND 500 MCG/KG) IN NATURALLY INFESTED CATTLE
» Área de pesquisa: ACAROLOGIA
» Instituição: CPPAR - Animal Health Research Center - Faculdade de Ciências Agrárias e Veterinárias, UNESP, Via de acesso Prof. Paulo Donatto Castellane, s/nº, CEP: 14884-900, Jaboticabal, São Paulo – Brazil
» Agência de fomento e patrocinadores:
The efficacies of 200 mcg/kg and 500 mcg/kg ivermectin against Rhipicephalus (B.) microplus strains were assessed in four experiments that were conducted on different rural properties. In experiment I, two groups of ten bovines, naturally infested with at least 20 ticks between 4.5 and 8 mm on the left side of the body were selected after three consecutive counts (days 3, 2 and 1 before treatment); one group was treated subcutaneously with 200 mcg/kg ivermectin and the other was held as a control. On experiments II, III and IV another 20 animals were selected for each trial following the same criteria, and divided in two groups of tem animals, one being hold as a control group and the other being treated with a pour-on formulation of 500 mcg/ kg ivermectin. In all experiments the parasites were quantified on days 3, 7, 14, 21 and 28 post treatment (p. t.) in order to determine the efficacy of the tested formulations, based on the geometric means of the parasite counts. In none of the four experiments a sufficient efficacy (average of efficacy on days 7 and 14 superior than 90%) was observed. The efficacy of 200 mcg/kg ivermectin was 72.04%. 500 mcg/kg ivermectin reached an efficacy of 79.03% in experiment II; 85.93% in experiment III; and 52.08% in experiment IV. The results from these experiments indicate that the resistance of R. (B.) microplus to ivermectin is widely disseminated, not only against 200 mcg/kg ivermectin, but against 500 mcg/kg as well.
