Anthelmintic Resistance Flashcards
What are the main NEMATODE causes of ovine PGE in Britain? (most common)
- H eamonchus contortus
- O stertagia [Teladorsagia] Circumcincta
- T richostrongylus Spp
- C ooperia spp
- Nematodirus Battus
Which species other than nematodes may cause ovine PGE in Britain? (less common)
- Nematodirus spp
- Oesophagostamum venulosum
- Chabertia ovina
- Bunostomum trigonocephalum
- Strongaloides papillosus
What are the main NEMATODE causes of bovine PGE in Britain?
Ostertagia ostertagi
Which species other than nematodes may cause bovine PGE in Britain? (less important)
- Cooperia spp
- Trichostrongylus spp
- Nematodirus helvetianus
> Lungworm also important (Dictyocaulus viviparous)
Give the main lungworm of cattle
Dictyocaulus viviparous
What are the most important horse worms?
Strongyles (redworms)
How are strongyles grouped?
Based on SIZE and LIFECYCLE > Migratory (Large) - S vulgaris, S edentates, S equinus > Non-migratory (Large) - Triodontophorus spp > Non-migratory (Small) - Cyathostomins (=trichonemes) [4 genera, 40+ spp] - Poteriostomum, oesophagodontus
Why are worm control STRATEGIES necessary?
- treatment fialures due to innapropriate product use and application
- resistance increasing
Why may worming treatments fail?
- Underdosing (estimating body weight, maintainence of equipment, poor technique, failing to follow manufacturers instructions)
- Incorrect drug for target worms
- Re-introducing animals to heavily contaminiated pasture
- Resistance
How is anthelmintic resistance spread through a population?
- Individual able to tolerate doses which are noramllyl lethal due to resistance alleles pre-existant in worm population
- this is heritable
- resistance develops slowly at first than more rapidly as allele frequency ^
What drench is most commonly resistant?
BZ (White)
Which broad spec anthelmintics have least resistance?
Aminoacetonitrite derivatives [4] and spiroindoles [5]
Which species has most reports of resistnace?
Sheep
Cows not so much
Which species are most resistant to ML?
Cooperia
What is the most likely cause of resistnece developing?
Underdosing pour on treatments