The warm wet weather which followed a cold period is ideal for hatching large numbers of nematodirus larvae which have been dormant on the pasture since last year. Lambs grazing pasture that lambs grazed last year, stressed lambs (e.g. triplets) or lambs with coccidiosis are at higher risk. SCOPS (Sustainable Control of Parasites in Sheep) advises farmers to dose high risk lambs with a white (BZ) drench.
Nematodirus can be very pathogenic commonly causing sudden death.