Parasites are the hidden face of climate change across Scotland

Scotsman: There is little doubt that climate change is having an impact on the agricultural industry in Scotland. The consensus is that this will lead to drier summers and increased rainfall during the winter. Scientists at the Moredun Research Institute, near Edinburgh, reckon that climate change will have a major impact on the health and welfare of livestock. Dr Philip Skuce has been studying this topic. He said: "Recent data from diagnostic reports clearly shows that the incidence of parasitic gastroenteritis, caused by roundworms, has risen significantly in the last five years.

"Heavy infestations with the brown stomach worm, teladorsagia circumcinta, are now routinely diagnosed in lambs in the spring in the south-east of Scotland. This is believed to be caused by the survival of the free-living larval stages shed in the previous year through the winter on pasture."

In the past farmers were able to combat the various parasites which infect sheep with a range of drugs. The problem is that new parasites are being found. Skuce added: "A very realistic threat is the emergence of haemonchosis in Scottish sheep flocks. This is a highly pathogenic, blood-sucking worm normally associated with more tropical climates, especially in Australia, South America and South Africa.

"The number of outbreaks has also increased in the last decade and it has even been identified on sheep farms in the extreme North-east of Scotland. It is unclear whether the parasite is over-wintering on pasture or surviving in an arrested state within the host until favourable conditions return in the spring.

"In any event, this is a serious development, partly due to the high pathogenicity, but also because of its ability to evolve successful survival strategies. In a similar way nematodirus, traditionally a parasite of young lambs in the early summer, now appears to have changed so that it is now seen in older lambs during autumn and winter."

Liver fluke has long been a scourge of the sheep industry. Traditionally it was more prevalent in the west, but it is now routinely diagnosed in drier parts of Scotland. However, fluke is now being increasingly found in cattle and reports from abattoirs suggest that up to 30 per cent of all livers are rejected

On the broader picture of parasite control, Skuce said: "The sustainable management of livestock parasitism in the face of climate change requires that we remain vigilant and retain the capacity to respond to a changing environment. We urgently need improved surveillance and diagnosis as well as better methods of detecting resistance to the commonly used drugs. Scientists at Moredun, in collaboration with the Glasgow Vet School and the Sanger Centre in Cambridge, have been successful in obtaining substantial funding to pursue this goal.

"We also need to continue our ongoing research towards alternative integrated control strategies such as vaccines, selective breeding and optimised nutrition to remove our reliance of a dwindling supply of effective veterinary products."

The actual cost of parasite infestation in cattle and sheep is difficult to quantify, but it certainly runs to many millions of pounds each year. An increasing trend to low-input systems of animal production means that the overall of supervision is reduced and relatively minor problems which would have been picked quickly in the past can suddenly become serious both in terms of animal health and lack of performance. Prevention comes a lot cheaper than expensive drugs.