Veterinary scientists have warned lambs are facing a high risk of Nematodirus worm infection this month and next (April and May, 2015).
Nematodirus infection results from the ingestion of large numbers of worm larvae on contaminated pasture.
Lambs grazing the same pasture in the previous year were the source of this contamination.
Nematodirus eggs passed out by lambs in 2014 will generally have remained unhatched on the ground throughout the winter. Given suitable conditions of moisture and temperature, they undergo mass hatching in the spring of 2015, resulting in a high risk of infection for lambs.
Affected lambs develop profuse scour and can die rapidly. Hatching of Nematodirus eggs has already commenced and meteorological readings indicate peak hatching taking place mid to late April.
Nematodirus normally only affects lambs between six and 12 weeks of age and clinical signs usually appear two weeks after ingestion of large numbers of larvae. Although rare, Nematodirus infection can occasionally cause problems in young calves.
AFBI, which provides scientific research and services to government, non-governmental and commercial organisations, says farmers should be on the alert for signs of scour in lambs and possibly young calves at grass.
It warns Nematodirus infection can be confused with coccidiosis, which also causes severe scour in young lambs. Treatments for Nematodirus infection and coccidiosis are different, so a vet’s diagnosis and treatment recommendation are essential.
AFBI’s veterinary sciences division can test faeces samples from sheep or cattle to determine the level of worm eggs present. A minimum of 5g of faeces from each animal is required for this test.