Epsilon Archive for Student Projects

Abstract

Anthelmintic resistance is a major problem in sheep husbandry all over the world. One way to
slow down the development of anthelmintic resistance is to keep part of the parasite
population in refugia (unexposed to drugs) which will maintain the genes for susceptibility
within the population. Climate, type of parasite and drenching regimes effect the size of the
refugia. Dilution of resistant with susceptible parasites, targeted treatment and targeted
selective treatment are all management strategies that employ refugia. Dilution is possible but
complicated. Targeted treatment means not drenching when there are few parasites in refugia
as this selects for resistance. Targeted selective treatment means only drenching animals that
need treatment. FAMACHA© has turned out to be an effective method to pick out the
animals which suffer from an infection with H. contortus. To use daily weight gain as an
indicator of which animals to treat is effective but costly. Five point check© needs
development and evaluation to be a useful alternative. The methods need to be simple, cheap
and functional in order to be used by farmers. There is also a need for foregoers among the
farmers that can show the others that the new methods work and do not lead to production
loss and a worsened animal health. Refugia delay the development of anthelmintic resistance
– it does not stop it.