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Spring 2008 - Parasitic Disease Forecast

The Department of Agriculture, Fisheries and Food, today issued the following advice to farmers in regard to parasitic diseases.

Nematodirosis in lambs

Nematodirosis is a severe disease usually found in 6-12 week old lambs, which become infected through ingesting infected larvae present on contaminated pasture. Infection is characterised by diarrhoea and wasting and mortalities in untreated lambs can be high. The disease is best prevented by keeping the current year's lambs off pasture that was grazed by lambs last year.

Recent meteorological information and soil temperature data indicate that in the south and southwest, hatching occurred in late March. In the rest of the country peak hatching occurred during the first and second weeks of April. Farmers should be aware that lambs might start to show clinical signs of infection two to three weeks from these dates.

It is possible that the mild winter may have reduced the synchronisation of the egg hatch and in some areas hatching may have occurred earlier this year. Farmers should therefore err on the side of caution, especially those with large sheep enterprises where fresh pasture is not available. Lambs, particularly those that are grazing on pasture where lambs grazed last spring, should be dosed with a suitable anthelmintic in late April or early May to decrease the likelihood of clinical problems later in the season and also to reduce the risk of pasture contamination for the next year.

Coccidiosis in lambs:

Farmers need also to be aware that other parasites cause diarrhoea in young lambs that 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 help prevent coccidiosis in young lambs as localised poaching creates moist conditions suitable for the spread of this parasite.

Farmers are advised to consult their private veterinary practitioner for an accurate diagnosis and advice on appropriate medication where severe diarrhoea and straining are observed in lambs. Faecal samples can be submitted to the Central and Regional Veterinary Laboratories of the Department for testing. This service is available through private veterinary practitioners and can be used to assess the level of parasite infection on farms and also to assist in the development of parasite control programmes.


This press release is prepared in conjunction with the Nematodirus Advisory Group. This group comprises representatives from the Department of Agriculture, Fisheries and Food; Teagasc; Met Eireann; University College Dublin and the Pharmaceutical Industry.

Date Released: 06 May 2008