Ovine campylobacteriosis (formerly ovine vibriosis)

Page last updated: Wednesday, 3 October 2018 - 1:23pm

Ovine campylobacteriosis is an infectious disease of breeding ewes causing abortion in late pregnancy. It is caused by the bacteria Campylobacter fetus ssp. fetus. The disease is found in sheep around the world, but is an uncommon diagnosis in Western Australia (WA). Campylobacter sp. bacteria were previously known as Vibrio species, and the disease has also been called ‘vibriosis’.

Zoonotic disease

Campylobacter fetus ssp. fetus can also infect humans, especially immunocompromised people, and may cause bacteraemia. Always wear disposable gloves and cover cuts and abrasions before handling aborted or potentially contaminated material. Always wash hands and change and wash clothes and disinfect shoes and equipment after handling contaminated material.

Signs of ovine campylobacteriosis

Ewes:

  • discharge from vulva for a few days, then
  • sudden abortion in late pregnancy causing the ewe little trouble
  • rapidly increasing abortion rate over several days (average outbreak is 20% of the flock, but varies from 5–50%, with rates of up to 70% reported)
  • birth of dead or weak lambs
  • brownish discharge from the vulva for up to two weeks following abortion (this discharge contains millions of the infectious bacteria)
  • up to 5% may die from blood poisoning following infection of the uterus.

It is rare for a recovered flock to have repeat outbreaks in successive years.

Lambs:

  • about 50% die in the uterus
  • liver lesions present in about 20% of aborted lambs (multiple 1‑20 millimetre, yellowish circular areas)
  • blood-tinged fluid in the cavities of the chest, abdomen and around the heart
  • oedema (swelling) of subcutaneous tissues
  • swollen placental membranes (afterbirth) with soft, pale orange cotyledons (buttons), instead of the normal red colour.

Infection and spread

Ewes are susceptible to infection during the second half of pregnancy. Susceptible ewes ingest bacteria from contaminated pasture or water.

The bacteria enter the ewe’s bloodstream and pass to the uterus where they multiply in the placenta, infect the placental membranes and cause abortion of the developing lamb. Abortion occurs one to three weeks after infection.

Aborted lambs and the afterbirth contain large numbers of the campylobacter bacteria.

When abortion occurs in a cool, moist environment, the bacteria survive and contaminate the area, allowing rapid spread of the disease to the rest of the flock.

When does ovine campylobacteriosis occur?

Campylobacter abortion occurs mainly during cold, wet seasons.

In WA, there have been some outbreaks of the disease in late summer and autumn. The spread of infection in arid seasons is associated with sheep congregating around areas of handfeeding and watering.

How does ovine campylobacteriosis enter a flock?

The initial entry of Campylobacter to a flock is usually impossible to trace. Sheep and cattle may harbour the bacteria in the intestines and become a source of infection for flocks.

Wild animals and birds may also carry the bacteria from one flock to another, or from one farm to another. Crows pass on the organism through their droppings and are attracted to handfeeding and watering points. Foxes are also believed to spread the disease.

Diagnosis

Round, yellow-white areas on the liver are often seen in foetuses aborted due to campylobacter infection.

To confirm diagnosis at a laboratory, veterinarians will need to provide samples of the foetal liver for selective campylobacter culture or PCR testing, placenta or maternal vaginal discharges, or formalin-fixed specimens of foetal liver for histopathology.

Blood samples can be used to test for antibodies from a flock suspected to have been exposed to Campylobacter. The most useful samples are paired serum samples taken as soon as possible following a suspect exposure then two to three weeks after the initial sample. Single blood samples, especially if taken some time after abortion, may indicate if a flock has been exposed to Campylobacter but can be difficult to interpret with regards to causality.

Treatment

There is no practical treatment to prevent campylobacter abortion. Once abortions commence, the placentas of infected ewes have already suffered damage.

Ewes that have aborted may be treated with antibiotics to reduce losses from uterine infection (metritis) or systemic infection.

Control

  • Isolate aborting ewes.
  • Collect and burn aborted lambs and placental membranes. Humans can become infected so it is important to wear disposable gloves and cover cuts and abrasions before handling aborted or potentially contaminated material. Always wash hands and change and wash clothes and disinfect shoes and equipment after handling contaminated material.
  • Prevent contamination of feed and water by vaginal discharges and aborted lambs. This includes providing water troughs at dams or soaks.
  • Do not sell ewes from an infected flock for breeding as some may be carrier animals.
  • Once infected, flocks usually develop good immunity.

A vaccine is available commercially that can provide immunity against Campylobacter. This should be used prior to potential exposure of a flock to Campylobacter.

For more information, contact your private veterinarian or local Department of Primary Industries and Regional Development, Western Australia veterinarian.

 

 

Author

Shane Besier