Worms in sheep: how they spread
Worm life cycle
Developing and mature barber's pole worms live in the abomasum of the sheep's gastrointestinal tract. Other worms such as the black scour worm and the nodule worm live in the small and large intestine respectively.
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Actively moving barber's pole larvae in dew drop waiting to be ingested.
They mate and lay eggs which are then carried out with dung onto the pasture.
In the dung, eggs hatch into infective larvae. If the dung remains moist, large numbers of larvae leave the dung pellet and move onto areas of pasture close to the ground. Infective larvae are a waiting stage and as long as the environment around them is quite humid, they can survive about 3 months until eaten by sheep. Conversly, hot dry windy weather will shorten the life of infective larvae. Once in the sheep, the larvae develop and mature into adult worms and the cycle begins again.
Worm infestations occur when large numbers of larvae survive on the paddock and are eaten during grazing. Any condition that causes dung to remain moist will promote the survival of larvae and provide a high risk of worm outbreaks.
Wet or humid weather
High risk weather is rain, storms or showers followed by about 4-5 days of cloudy or humid weather. The outer crust of dung pellets will be soft, enabling large numbers of worm larvae to move onto the green pick. During these high risk times, producers should increase their monitoring and testing, and be alert for signs of infection such as pink or white lower inner eyelids (red is healthy), reluctance to move and a "tail" forming on the mob when mustered.
- Even in prolonged dry weather, larvae can survive in sheltered areas under trees.
Moist, sheltered areas
Even in prolonged dry weather, some conditions can cause dung to remain moist enough for larvae to survive and infect paddocks. For example, larvae can survive for long periods along bore drains, near dams and under trees.
More information:
- WormBuster testing service
- Worms in sheep: problem worms
- Worms in sheep: using drenches
- Worms in sheep: quarantine drenching
- Worms in sheep: smart grazing
- Worms in sheep: worm resistant sheep
Who to contact:
- Contact the DPI&F WormBuster Laboratory by phoning the DPI&F Business Information Centre on 13 25 23 between 8 am and 6 pm weekdays or emailing callweb@dpi.qld.gov.au.
Last updated 03 April 2008
Worm and drench testing
The DPI&F WormBuster testing service is an essential tool to assess worm burdens and the effectiveness of chemical drenches.