Campylobacter in Sheep
Campylobacteriosis (previously called vibriosis) is the second most common cause of abortion and foetal loss in ewes in New Zealand, after Toxoplasmosis.
Campylobacter usually causes abortion in the last six weeks of pregnancy, but it can also be responsible for the birth of weak lambs. As a general rule, the ewes suffer no ill effects and retain their fertility for future years. Once exposed to Campy they also develop immunity to subsequent infections. A small percentage may develop a uterus infection and die, but this is uncommon. Campylobacteriosis occurs in most sheep-raising countries of the world and a high prevalence has been reported throughout New Zealand. Infection is caused by C.fetus of which there are many strains present in New Zealand.
The bacteria may live in the intestine of sheep, these ewes are effective carriers. The infection may enter a flock by ingestion of contaminated food or water or by direct contact with aborted foetuses or foetal membranes. Birds that scavenge lambing paddocks, such as black gulls and harrier hawks, may aid in carrying the bacteria from one farm to the next. Introduced carrier sheep may bring an infection onto a farm carrying the bacteria in the intestines or gall bladder and an abortion storm may follow.
In contrast to Toxoplasmosis, which tends to cause early pregnancy loss, Campylobacter results in abortion in the last third of pregnancy and is mainly seen in maiden ewes. The interval between infection and abortion may range from 7 to 113 days. Some ewes may carry their lambs to term resulting in the birth of dead or weak lambs. Abortion storms can occur in particular when ewes are grazing short grass at a high stocking rate. Shedding of Campylobacter spp. varies with season and diet.
Diagnosis is best made by post-mortem of dead lambs. However, if this is not practical on farms with little to no shepherding (the norm on hill country), a blood test is available to screen wet/dry ewes for Campylobacter antibodies. This needs to be carried out around the time of docking.
Campylobacter infections can be prevented by vaccination. The programme requires 2 shots 4-6 weeks apart and is best started at least 4 weeks before mating. Ewes can be vaccinated with Campy at the same time Toxovax is given, just on opposite sides of the neck. Campyvax needs to be given under the skin, while Toxovax needs to go into the muscle. While the vaccine company recommends an annual booster with Campyvax most farmers find the 2 shot programme received as two tooths gives lifetime protection.