Resistencia a los antihelmínticos en el sur de la Provincia de Misiones y noreste de la Provincia de Corrientes

Despite continuous messages and recommendations coming from different sectors such as academic groups, industry and private practice professional advisors activity, the control of parasitic diseases in beef and milk cattle has been carried out for several decades almost exclusively by the administration of different anthelmintics. Diagnosis and control are two inseparable actions of any health program. Knowing the causal agent is not sufficient, since it is also essential to determine the degree of sensitivity of parasitic populations to the available chemical groups. The phenomenon of anthelmintic resistance (AR) is a global problem involving all those regions that allow the development of livestock in pastoral systems. The aim of the present study was to determine the prevalence of AR in cattle in the southern of Misiones and northeast of Corrientes. The study area includes 7 farms distributed as follows: 5 in Corrientes (Ituzaingo and Santo Tome districts) and 2 in Misiones (Apostles and Capital districts). The study was conducted from March 2014 to August 2016. The unit of analysis was the weaning calf, and the diagnostic technique used was the “Fecal Egg Count Reduction Test (FECRT). The test could be performed only in 4 establishments in the province of Corrientes, where the prevalence of AR to ivermectin was 100 % and to benzimidazole, 25 %. The parasite genera resistant to ivermectin were Haemonchus spp and Cooperia spp. The FAO Technical Cooperation Project (PCT / RLA / 2364) study carried out in 1994-1995 showed that resistance was present in 60 % of the herds studied and most of them (55 %) was resistant to the ivermectin group. Consequently, our results demonstrate an increase in AR when compared with previous studies conducted in the country.