Nematodirosis is a severe disease in both lambs and calves and SCOPS (Sustainable Control of Parasites) has issued a warning to farmers to be on guard with temperatures set to increase this week. April is generally the time that farmers should be dosing against the disease, which affects lambs and calves of up to 12 weeks old.
SCOPS warn that many areas in the UK are at risk, with Northern Ireland also at low risk. There have been some areas, listed in SCOPS forecast map, in the Republic which are also at risk. These include Waterford, which is at low risk, and coastal regions in Mayo and Kerry, which are at moderate risk. Moderate risk means that eggs of the parasite are within ten days of hatching.
Leslie Stubbings of SCOPS said the rapid change in temperatures poses a serious danger.
“The rapid change from the relatively cold weather of March and early April to the forecast for the second half of April means a mass hatch of over-wintered Nematodirus larvae is highly likely in some areas. This poses a serious danger to February and March-born lambs grazing fields that carried lambs last spring.”, She said.
“With such a challenging season to date, we are urging sheep farmers to check their nearest weather station on the website and assess the risk to their lambs, because reports of early cases highlight the variation in hatch date from farm to farm.”, she added.
What It is:
A severe disease. which infects animals through the ingesting large numbers of infective larvae present on contaminated pasture.
The life cycle of the Nematodirus battus worm is unlike that of other roundworms in that, typically it takes almost a year before the egg hatches releasing the infective larvae. There is a mass hatching of larvae in spring when the soil temperature increases after a period of cold weather and disease typically occur in April, May and June.
Side effects - Infection is characterised by profuse diarrhoea, dehydration and weight loss.
Mortality can be high in untreated lambs and calves. After ingestion, Nematodirus larvae invade the intestinal mucosa and in some cases, death may occur before signs of diarrhoea are observed. Ewes will though, appear clinically normal. This disease is best prevented by keeping the current year’s lambs off pasture that was grazed by lambs or young calves last year.
It is also important that farmers are aware that other parasites cause diarrhoea in young lambs and require different control measures and medication. Nematodirus can be wrongly assumed to be the cause of severe diarrhoea in lambs when in fact the cause is a coccidial infection.
Rotation of pasture and frequent movement of feeding troughs and watering points to drier areas will help prevent coccidiosis in young lambs as localised poaching creates moist conditions suitable for the spread of this parasite. Raising feeding troughs will also help reduce the contamination of feed with faeces.
It is advisable to consult a private veterinary practitioner for an accurate diagnosis and advice on appropriate medication if lambs with severe diarrhoea and straining are observed. This is especially the case where there has been little or no response to an initial treatment. Both nematodirosis and coccidiosis can occur at the same time in the same lambs, so treatment may need to be targeted at both pathogens.
Many farmers have already reported infection on their farms, though mostly in the UK. You can keep an eye on the SCOPS forecast map here.