Scientists bid to beat killer sheep disease

Scottish scientists are developing a new vaccine to help farmers and crofters protect their sheep from enzootic abortion.

Researchers at the Moredun Research Institute, based in the outskirts of Edinburgh, say their findings could lead to a new, more effective vaccine for ovine enzootic abortion – also known as chlamydial abortion.

The disease, one of the most common infectious causes of abortion among sheep in the UK, is caused by the bacteria Chlamydia abortus, which invades the placenta during pregnancy and can also cause lifethreatening illness and abortion in humans.

The disease is easily spread because infected lambs, placentas and excretions provide a source of infection to other sheep through ingestion and inhalation.

Moredun’s Dr David Longbottom said although there are vaccines available on the market to tackle the disease, they are not always effective.

He said commercial live vaccines, which use a weakened form of the Chlamydia abortus bacteria, have been shown to cause both abortion in some of the host sheep and transmission to other unvaccinated animals.

Inactivated vaccines, which use a killed form of the bacteria, have also been shown to be less effective in protecting animals from infection and immunity is more short-lived, added Dr Longbottom.

He said his team had completed the first stage of development of a new vaccine that’s similar to the live variation, but without the ability to grow and cause infections in the host animal.

“We are very encouraged that the new vaccine results in a similar protective response to that generated following a natural infection or resulting from the live vaccines, but importantly without the ability to cause disease,” said Dr Longbottom.

Researchers will now work to develop the vaccine further.

AT RISK: Scientists are working on a vaccine to protect sheep from enzootic abortion.