The Department’s Nematodirus warning which is featured on this week’s sheep page was joined this week by a warning released by AFBI for farmers in Northern Ireland.

The AFBI warning points to peak hatching taking place in the first and second week of April and recommends farmers to be conscious of the risk and keep an eye out for symptoms including scouring from mid-April onwards.


Nematodirus can often be confused with coccidiosis, which has similar symptoms and also has the potential to cause significant damage in a short period of time.

The greatest risk with coccidiosis is generally in lambs aged from three to eight weeks of age, with symptoms most evident in lambs aged six to eight weeks and hence raising the possibility of the disease being confused with nematodirus.

Both diseases cause a bad scour and quickly dent lamb performance. Nematodirus gives rise to a green scour whereas the characteristic scour with coccidiosis is a dark grey or blood-stained scour that is often black in colour as a result.

Lambs can be seen straining and performance will quickly suffer, with high mortality levels common during an outbreak. Lambs develop resistance to coccidia with age (10 weeks and older) but at this stage great harm can be done, with lambs finding it difficult to recover.

Disease prevention

Coccidiosis generally occurs where lambs become infected orally from faecal contamination, with areas such as dirty bedding, contaminated feed and water troughs and pastures the main entry routes due to higher numbers of oocysts (coccidial eggs) present. Therefore, the focus must be on prevention.

Where lambing is in the final stages, it is important to maintain high standards of hygiene until the last ewe has lambed. Bedding should be kept dry and feed and water troughs should be raised to limit contamination.

Where ewes are being supplemented outdoors, it is important to keep troughs moved regularly and to avoid placing troughs where animals are naturally congregating. Keeping lambs of a similar age in batches will also help.


Treatment is via oral coccidiostats, with a number available on the market. It should be noted some of these treatments have a residual period of cover and this is another reason for keeping lambs of a similar age grouped together.