Control of ecto and endo parasites Flashcards
Non chemical measures for GIN
- grazing management
- using immunity to worms
- genetic selection for resistance
- vaccination (not yet)
- integrated strategic drenching programs
Factors: Age
young animals get more worms, suffer more serious disease and shit out more eggs onto pasture
Grazing history
Animals exposed to heavily infected pastures get more worms
Climate
The weather affects which worm species are found in a locality. Warm, wet weather advantages parasites to develop and survive on pasture
breed
Some breeds and lines of sheep inherently carry fewer worms
Nutrition
Improved nutrition can reduce worm numbers and production costs of worms by boosting resistance
Immunity/resistance
Sheep develop immunity as they age. Older (immune) sheep carry fewer and suffer less from disease
Principles of worm control
- Worm life cycle and pasture numbers; warm and moist conditions enhance build-up and survival
- survival of L3 on pasure- extremes are usually lethal. Warm to hatch, cool to dry
- L3 don’t feed. Sooner or later run out of energy- faster w warmth
- rainfall zones
IPM strategies PxE
- Reducing development of parasite eggs on pasture
- Minimising infective stages (L3) available for infection
- Minimising infective (L3) ingested
IPM strategies HxP
- Minimising worms establishing and completing life cycle w egg production
- minimising eggs coming out of hosts
- maintaining host production (minimising prod. losses)
- Checking to ensure it is working
Grazing management: Strategies for reducing pasture contamination
- Spelling for 3-6 months esp over summer
- Cropping, forage, bushfires
- Grazing w adults or a different species (not goats)
- Keep pasture long, strip grazing
- Drench, hold and move to low L3 pasture
Innate immunity
30% of worms don’t establish in naiive lambs due to steroid sensitivity
Inflammation
worms don’t like a hostile location- inflammatory mediators expel worms
Acquired immunity
- allergic TH2- type responses are involved in protection
- induction of immunity is worm-specific, effector phase is non-specific (inflammatory mediators), expelling unrelated worms in same location
Breeding for resistance
- animals can be selected for resistance
- reduced epg is correlated w increased bodyweight
DrenchPlan is an integrated worm management combining
- the effective use of drenches
- grazing management
- flock management including early weaning
- breeding sheep more resistant to worms
- nutrition
- fine-tuning based on regular worm egg count monitoring (WormTest) and drenching efficiency testing (DrenchTest)
IPMS aims to
reduce infection of susceptible stock by minimising pasture L3
IPMs reduce selection pressure for resistance by
reducing the frequencing of drenching
IMPS require
effective drenches
Managing anthelmintic (anti-parasite drugs) resistance required an entirely different strategy:
Aims to dilute out Res worms w Sus ones, so contaminates pasture
Prevention: break lifecycle
- Stop dog (final host) eating infected animal tissue
- Prevent transmission to livestock by stopping dog shit spread
- Treat infected dog with anthelmintic
- Employ measures to prevent wild dogs from roaming on grazing pasture or contaminating it with eggs (bait on property with praziquantel)
Ectoparasite IPM scheme
- Environmental control
- Attention to susceptible groups (young,stressed) esp for nutrition
- Rational use of effective chemicals
- breeding for resistance
- nutrition, vaccination
- Monitoring and feedback; production and chemical efficacy
Benzolyphenylureas and triazines
chitin synthase inhibitors used for flies and lice
Juvenile Hormone
used for fleas and roaches
Environmental control for parasites with life cycles entirely on animal:
- removal of hair/fleece to enable access of chemicals
- chemical treatment, dip, backliner
- preventing animal to animal transfer- cages
- clean up shed hair, bedding
