Parasite replacement as a tool for reversing anthelmintic resistance

• Grant number: 24/19696-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2025
• End date: December 31, 2025
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Preventive Veterinary Medicine
• Principal Investigator: Ana Carolina de Souza Chagas
• Grantee: Estevão Camillo da Costa
• Host Institution: Embrapa Pecuária Sudeste. Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA). Ministério da Agricultura, Pecuária e Abastecimento (Brasil). São Carlos , SP, Brazil
• Associated research grant: 21/02535-5 - Parasite-host-environment approach to control anthelmintic resistance in sheep flocks, AP.TEM

Abstract

The current situation of anthelmintic resistance in Brazil indicates low expectations for increasing the number of small ruminants. However, studies indicate that the effectiveness of anthelmintics (AH) can be restored by replacing the parasite population in sheep, herein called worm replacement (WR). Thus, the present proposal aims to evaluate and monitor the effect of partial and total replacement of the Haemonchus contortus population in different sheep breeds on the status quo of anthelmintic resistance. To evaluate WR, it is necessary to maintain infected sheep as feces donors for egg recovery, fecal cultures and recovery of infective larvae of susceptible Haemonchus contortus strain. This requires that the feeding and health management measures of the animals be controlled and frequent, ensuring the welfare and success of the experimental protocol. In addition, 180 ewes and approximately 180 lambs will be kept on pasture, which will be phenotyped for their level of resistance to H. contortus, through collection of fecal samples (EPG, coprocultures), blood (hematocrit, NIRS), Famacha scores, weighing, etc. In this way, the results of such activities may contribute to the validation of the WR for the management of anthelmintic resistance of the parasite H. contortus.