Camplyobacter Abortions in Sheep
The bacterium, Campylobacter fetus. Formerly known as "vibrio".
The Disease Cycle:
A small number of carrier ewes will be persistently infective and may pass the disease to pregnant ewes via faeces or aborted material (i.e. infection is oral). These newly infected ewes abort in late pregnancy and the cycle can continue.
Most ewes that abort will develop strong immunity but some carrier sheep will always be present. Thus outbreaks will occur every few years as replacement stock will have no immunity and the carrier ewes in your flock will be available to pass the infection onto these susceptible ewes.
Ewes usually abort in the last six weeks of pregnancy and you will generally just find dead premature lambs, although some ewes may carry weak lambs to full term.
This translates to poorer than expected lambing percentages and more dry ewes.
There are few consistent specific signs of Campylobacter infection and to confirm the cause of abortion, aborted lambs should be submitted to the veterinary clinic for post mortem and sampling.
What do you do?
Unfortunately, there is little you can do to halt the outbreak this year.
However, to limit the extent of the abortion storm, you should:
- a. Collect and destroy the products of abortion as soon as possible, and
- b. Isolate aborted ewes from the main flock for at least 7-10 days.
In future years, you should vaccinate ewes yearly with Campylovexin/Campyvax 4 as follows:
- a. First year - Vaccinate all ewes (two tooths and older) twice pretupping, at least four weeks apart.
- b. Subsequent years - Vaccinate two tooths twice pretup at least four weeks apart. Older ewes need pretup vaccination only.
NB: If you are mating hoggets, they should get two shots pretupping in their first autumn and then annual boosters as two tooth and older. If you are not mating hoggets, they get the two shot regime before mating as two tooths- there is no need to do it sooner.
New stock should be treated as two-tooths and be vaccinated twice.
Although flock protection will not necessarily be complete, you could opt to just vaccinate replacement ewes yearly and accept that immunity will gradually decline over the following years. Older ewes may still be vulnerable but the risk is lowered and the overall cost is reduced. Local experience suggests that this is effective as we rarely see abortion in flocks where a two-shot regime was used in either hoggets or two tooths.
The vaccine costs approximately 46-50c exc. per dose and is the only effective method of ensuring that the disease cycle is broken.