Nematodirus Risk Advisory

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 2016

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 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 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 before signs of diarrhoea are observed. Ewes will 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.

Forecasted timing of infection and treatment this spring

The maximum Nematodirus larval count on pasture is expected by the end of the first week of April in the extreme west of the country, with peak larval counts occurring in the rest of the country by the second week (in Connaught and coastal counties in Munster and Leinster) and third week (in inland counties) of April. Lambs may show clinical signs of infection two to three weeks from these dates of peak hatching.

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