Anthelmintics Resistance Flashcards
How much resistance does each of the drug categories have?
BZs- extensive resistance
LEV/PYR- resistance emerging
MLs- Resistance emerging
In sheep and goats which species of parasites have shown anthelmintic resistance?
Nematodes- haemonchus contortus, telodorsagia circumcincta, nematodirus battus, trichostronglus spp
In cattle which parasites have shown resistance?
Nematodes- Cooperia oncophora, oestertagia ostertagi
Trematodes- facial hepatica
Which parasite species have shown resistance in horses?
Cyathostomin spp, parascaris equorum
What are the strategies for control for anthelmintic resistance?
Prophylaxis- To prevent high levels of parasite infection by reducing transmission, therefore reducing the incidence of disease/production losses
How can rate of selection for resistance be reduced?
Preserve drug efficacy for as long as possible
What influences development of resistance?
Parasites biology
Selection pressures
Proportion of parasite population ‘in refuge’- untreated
When should resistance be suspected?
Therapeutic- failure to treat animals with disease so clinical signs persist post-treatment
Prophylactic- when FEC remains high or clinical signs persist following treatment
How can resistance be diagnosed?
Faecal egg count reduction test- compare post treatment mean to control group. Effective >95% reduction, resistance <90% reduction
What are other options than resistance for drug failure?
Inadequate dosage, activity of drug reduced (storage), parasites species/stage, error in methods used for FEC
How is control of resistance going to be sustained?
Selective treatment most important
What are some non-drug based ways of managing resistance?
Grazing management, host genetic resistance- breeding
What are the recommendations of SCOPS?
Sustainable control of parasites in sheep
1) engage with vet
2) quarantine stragegies
3) test AR
4) give drugs effectively
What are the recommendations for cows?
Control of Worms sustainably
1) Use drugs when only necessary
2) select appropriante wormer
3) use strategies to preserve susceptible worms on farm
4) reduce dependence on anthelmintics
