How does anthelmintic drug resistance occur?
Anthelmintic resistance (AR) is defined by Køhler as genetically transmitted loss of sensitivity of a drug in worm populations that were previously sensitive to the same drug [6]. In a worm population, alleles coding for resistance will be present as a result of mutations, also in unexposed populations.
How does antiparasitic resistance occur?
After an animal is treated with an antiparasitic drug, the susceptible parasites die and the resistant parasites survive to pass on resistance genes to their offspring.