Nematodirus Risk Advisory 2017

The Department of Agriculture, Food and the Marine advises farmers in relation to the predicted risk of infection in livestock based on the advice received from the Nematodirus Advisory Group.

Source: DAFM – Press Release, April 2017

About the disease

“Nematodirosis is a severe disease of lambs six to twelve weeks of age, which become infected through ingesting large numbers of infective larvae present on contaminated pasture. The life cycle of Nematodirus battus is unlike that of other roundworms in that, typically it takes almost a year before the egg (Figure 1) 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 occurs in April, May and June.

Infection is characterised by profuse diarrhoea, dehydration and weight loss. Mortality can be high in untreated lambs. After ingestion, Nematodirus larvae invade the intestinal mucosa and in some cases death may occur even before clinical signs of diarrhoea are observed. Ewes are not affected. This disease is best prevented by keeping the current year’s lambs off pasture that was grazed by lambs or young calves in the previous year.

When is disease predicted to occur this year and when to treat?

The peak hatching of Nematodirus larvae is predicted to be the last week of March along the south coast of Ireland, and into the first week of April for most of the rest of the country. Nationally soil temperatures are warmer than normal for this time of year leading to maximum larval hatching occurring 1-2 weeks earlier than in recent years. Lambs may show clinical signs of infection two to three weeks from these dates of peak hatching.

Along the south coast of the country, lambs should be dosed with a suitable anthelmintic by the second week of April (two weeks post peak larval hatching), while lambs in the rest of the country should be dosed from mid April depending on farm location and individual flock factors. This will help to decrease the risk of clinical disease and reduce pasture contamination for the next year.

… “

Read the full press release on the Department of Agriculture, Food and the Marine’s website