The National Animal Disease Information Service is warning the spring season from April will bring high parasite risks for sheep and cattle, particularly affecting new-borns and the very young.

To prevent the high risk of disease due to infection with nematodirus in sheep, farmers are urged to avoid grazing lambs on pastures previously used for young lambs during 2012. There is an increased possibility of disease following the colder February conditions, which are similar to those seen in 2010 which resulted in a high incidence of nematodirosis.

Farmers are also advised to treat lambs to prevent parasitic gastroenteritis, which could become a problem should the weather prove wet during the spring/summer.

In most years, sheep only pick up low levels of overwintered fluke infection (metacercariae) from the pasture in March. This year, with the potential for massive contamination of the pasture last year and the lack of a hard frost in many places to reduce fluke numbers, the risk is much greater. Occasional losses due to acute fluke disease regularly occur in March, but there may be many more this year. Perhaps even more importantly, burdens of fluke may be acquired leading to chronic disease which may not be treated for many months.

Treatment of potentially infected stock in the spring with a drug to kill adult fluke is generally recommended in order to reduce fluke egg contamination of the pasture, reducing the risk later in the year. In addition, this year there may be many cases of undiagnosed chronic liver fluke which require treatment for their own immediate benefit, and furthermore animals grazing this month may be picking up fresh infection and require re-treatment effective against immature fluke (perhaps after 5 or 6 weeks). It is important that local risk factors are taken into account and a treatment/control plan drawn up with veterinary advice.