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South Australia worms, flies and lice update - January 2018

SA WormBoss Worm Control Programs

SA WormBoss Drench Decision Guides





Adelaide: Colin Trengove, Sheep Health Lecturer (UA Roseworthy campus) (

A hot January has dimmed memories of rainfall received in early December, but the impact persists with two thirds of the worm egg counts (WormTest) from the south east to the west coast during December/January being high enough to warrant a strategic drench.

The presence of worms in sheep during summer is generally associated with climatic conditions, grazing management and drenching history rather than age, sex or stage of pregnancy. The recent worm egg count results indicate many mobs drenched in spring need a follow up summer drench.  In order to minimise the risk of drench resistance developing it is recommended, especially in summer, to monitor for the presence of worms first before considering a drench. Contrary to past recommendations it is now preferred to avoid summer drenching altogether unless specifically necessary.

The rainfall in early December did result in some cases of barber’s pole worm or Haemonchus infestations and the use of the molecular diagnostic test (SNP or Strongylid Nematode PCR) did assist in rapid determination of this risk. While the risk of Haemonchosis has now passed, ongoing worm testing is recommended to check that worms are not contributing to production loss as feed quality and quantity deteriorates over summer.

Another worm risk usually overlooked is lungworm. There are three types of lungworm in sheep with two protostrongylid species requiring an intermediate development stage in land snails or slugs. This generally means access to irrigated pasture during summer. The third and largest type, Dictyocaulus filaria, has a direct lifecycle and is readily seen on post mortem. The most common lungworm in sheep and goats, Muellerius capilllaris, is only 1-2cm long and rarely noticed on post mortem. The common drenches are not considered effective in controlling it and it can be a precursor to pneumonia – as with all lungworms. An additional complication is that routine worm egg monitoring does not detect lungworm and a special diagnostic technique is required – Baermann technique, which most laboratories offer. If you have noticed sheep coughing or you have been made aware of significant pneumonia prevalence on abattoir traceback, you should consider testing dung for lungworm. They could be causing significant production loss without obvious signs – especially in lambs. Fortunately, most of the popular drench chemicals are effective in controlling Dictyocaulus and Protostrongylus species. However, Muellerius is a different matter and most products, including in our experience a double–active: monepantel with abamectin and a triple-active: levamisole, albendazole and abamectin, are not effective. Two papers, one in sheep and one in goats, did find that moxidectin, was effective:

For January 2018 state outlooks, please follow the links below:
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