2024 nematodirus risk map launched

The forecast predicts the hatch date for nematodirus based on temperature data from 140 weather stations throughout the UK. Use this in combination with your grazing history to assess the risk of nematodirus infection in your lambs.

Lesley Stubbings, an independent sheep consultant and SCOPS spokesperson explains: 

“A sudden increase in temperature after a period of cold weather can trigger a mass hatch of Nematodirus battus worms from eggs that have laid dormant since the previous season. If this coincides with the time when lambs are starting to take in a significant amount of grass, the result can be devastating."  

Nematodirosis is caused by large numbers of immature larvae that lambs consume from the pasture.

These immature larvae are not producing eggs, so this is the one time of year when faecal egg counts (FECs) aren’t as useful. Instead, keep an eye on the forecast – which is a free, online resource – and consider your individual risk factors.  

Nematodirus risk factors

• Lambs are grazing pasture that carried lambs last spring
• Lambs are old enough to be eating significant amounts of grass
• Lambs are in groups where there is also likely to be a challenge from coccidiosis (e.g. mixed aged lambs)
• Lambs are under stress (e.g. triplets, fostered, on a young or older ewes)
• A sudden, cold snap followed by a period of warm weather