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Parasite Matters Spring 2022

We have had quite a mild winter, with December, January and February all being on average warmer than usual. It has also been a relatively dry winter, with some exceptions in the Midlands. So, what does this mean for parasite activity? Temperatures in January remained lower than 10°, leaving most parasites inactive. However, particularly in the South of the country, temperatures rising over 10 were also paired with heavy rainfall – creating a warm and wet environment extremely favourable to parasite activity. In fact, SCOPS (Sustainable Control of Parasites in Sheep) started their annual nematodirus forecast earlier than usual.

Weather Charts from Winter 2022 - courtesy of the Met office

As Spring approaches, our sheep and cattle will be susceptible to both ecto- and endo-parasites: ticks, blowfly strike (for sheep), biting and nuisance flies & coccidiosis, nematodirus (for lambs), GI worms and liver fluke.


  • Ticks Starting with ticks. As for other parasites, tick activity relates to weather. However, all it takes is one sunny day in a sheltered spot so we can expect to see ticks almost year-round. The risk associated with ticks is the diseases that they carry – therefore, proper precautions must be taken. Avoid known tick hotspots if you can or preemptively dip sheep in Organo-phosphate (OP) or treat with an Synthetic Pyrethroid (SP) product.
  • Blowfly As temperatures stay above 9°, blowfly strike risk will increase. The threat starts off low, with a small number of flies in the first hatch but go on to multiply during the summer if they are left to breed and survive. As always, keep an eye on the NADIS and Farm Animal Health’s blowfly tracker to know when the risk is rising and when to act. Same goes for biting and nuisance flies – early action is key to reduce activity for the rest of the season.
Nematodirus in lambs

  • Coccidiosis is one of the first challenges your youngstock may be facing. Good immunity is acquired over time, so only naïve animals are at risk. Particularly, calves that have been housed longer or turnout in wet conditions. Hygiene, grazing management and targeted treatments should be part of your strategy to control coccidiosis.
  • Nematodirus forecast is up and running and this is the forecast of the first week of April. We can see that risk is high and very high in the South, as the weather has been warming up, and low-to-moderate risk in the North. A Grp 1 BZ white wormer (e.g. Rycoben) is the treatment of choice for Nematodirus in lambs. These are short acting products so the timing of treatment is also important – i.e. when the risk is rising.
  • Due to the mild winter weather (not too hot, not too cold), it’s likely that in some areas pasture larval survival rates will have been high (i.e. a lot of over-wintered worms). This can be a significant factor in the worm challenge now, in Spring, meaning there might also be other worms present at the same time as the Nematodirus challenge for cattle, young stock will benefit from early season monitoring as well.
liver fluke snails in mud

  • Fluke Despite the mild autumn and winter, low snail numbers (as a result of the hot dry summer) meant the overall fluke challenge remained low. The main risk to consider now is the fluke that have survived any winter treatments inside the animals. Checking dung samples for fluke eggs will identify any groups still carrying fluke, and a targeted treatment with an adulticide (albendazole, oxyclosanide or clorsulon) will remove these fluke, minimize the number of eggs reaching the pasture, and minimize the fluke challenge for the autumn.

Parasite Matters Archive

Parasite Matters Autumn 2021 (published September 2021)
Parasite Matters Summer 2021 (published June 2021)
Parasite Matters Spring 2021 (published March 2021)

CLiK™ EXTRA 65 mg/ml Pour-On Suspension for sheep contains dicyclanil and is indicated for the prevention of blowfly strike on sheep caused by Lucilia sericata or Wohlfahrtia magnifica. CLiK™ Pour-On for sheep contains 5% (w/v) dicyclanil and is indicated for the prevention of blowfly strike due to Lucilia sericata or Wohlfahrtia magnifica on sheep CLiKZiN™ Pour-On Suspension for Sheep contains the active ingredient dicyclanil and is indicated for the prevention of blowfly strike on sheep due to Lucilia sericata. Dectomax 5 mg/ml Pour-On Solution for Cattle contains doramectin and is indicated for treatment of gastrointestinal roundworms, lungworms, eyeworms, warbles, sucking and biting lice, mange mites and hornfly in cattle. POM-VPS Flypor™ 4% w/v pour-on solution contains 4% w/v permethrin (cis:trans 80:20). Legal category: POM-VPS. Rycoben™ SC 2.5% w/v Oral Suspension for Sheep contains cobalt sulphate, ricobendazole and sodium selenate, and is indicated for the control of broad spectrum roundworms, tapeworms, lungworms and fluke in sheep. POM-VPS. Advice should be sought from the medicine prescriber prior to use. Use medicines responsibly ( Weather maps courtesy of the Met Office. For further information call Elanco Animal Health on +44 (0)1256 353131, or write to Elanco UK AH Limited, Form 2, Bartley Way, Bartley Wood Business Park, Hook, RG27 9XA. CLiK™ EXTRA, CLiK™ Pour-On, CLiKZiN™, Dectomax™ Pour-On, Flypor, Clikzin™, Elanco and the diagonal bar logo are trademarks of Elanco or its affiliates. ©2022 Elanco or its affiliates. PM-UK-22-0317