Author: Farm Vets South West

“A nematodriosis outbreak can leave you with sick and dead lambs very quickly. Use the pasture grazing history and the weather patterns to avoid being caught unaware.”

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FVSW Bridgwater
Unit 8, Sedgemoor Auction Centre, Market Way
North Petherton, Somerset TA6 6DF T: 01278-663399 F: 01278-661135

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5 Larchfield Industrial Estate
Dowlish Ford
Ilminster, Somerset, TA19 0PF T: 01460-55004 F: 01460-55007

Stopgate Cross
Yarcombe, Honiton Devon
EX14 9NB
T: 01404-861214 F: 01404-861363

Information on:

Nematodirosis

Your local partner in farm animal health

Information leaflet: Nematodirosis

Nematodirus battus is a species of parasitic worm which affects sheep. Its epidemiology is rather different to other worm species (i.e. those causing PGE) thus it is considered separately here.
Disease Process
Nematodirus battus lives within the lamb’s intestine and irritates the lining of the intestine. This results in much fluid loss into the gut and so severe diarrhoea results. Deaths occur due to dehydration.
Signs of Nematodirosis:

Profuse watery diarrhoea, often green
Lamb stands tucked up
Dullness
Sudden death

Epidemiology
N. battus is different to other parasitic worms in that the worm larva develops within the egg and the infectious stage only usually survives a short period of time after it hatches. Hatching is triggered by an increase in temperature (>10’C) after a cold spell. Lambs develop immunity relatively rapidly and become less susceptible over 3 months of age. Consequently lambs are susceptible, usually, for a short period
(4-12 weeks of age). Adult sheep play little role in the epidemiology of N.battus. The disease is passed from lamb crop to lamb crop.

Control of Nematodirosis
Graze young lambs on pasture which didn’t have young lambs on it the previous year. Lambs born early may be age-immune by the time hatching occurs, while in an early, warm Spring, the majority of N.battus hatching may have occurred before later-born lambs are grazing.
Use the NADIS parasite forecast to predict the level of risk on your farm (www.nadis.org.uk). As lambs can be infected by very large numbers of worms after a hatching event, disease may be seen before the worms are old enough to produce eggs. Thus faecal worm egg counts (FWECs) are less useful in guiding treatment than in PGE.
Treat-at-risk lambs (those 4-12 weeks of age on at-risk pasture) during the risk period with a benzimidazole anthelmintic (white drench).
Depending on the risk forecast and the age of the lambs during the risk period, 1-3 treatments may be required at 3 week intervals.

Information leaflet: Nematodirosis