Brucellosis

Description

This disease is caused mainly by the bacteria Brucella suis. In rare occasions other Brucella species (including B. abortus, B. melitensis) can infect pigs. Brucella suis does not exist in the UK, Ireland and some other countries of the EU, Canada and most of the states of the US, but it is disseminated in most of the rest of the countries which produce swine. It is an important disease, because it can be transmitted to humans causing severe disease. The carrier status persists during long periods of time.

The bacteria can survive outside the pig during long periods of time, particularly at freezing or near freezing temperatures.

When a sow gets infected, the organism establishes in the placenta, causing inflammation and ultimately abortion. B. suis infects the testicles and the accessory reproductive glands, and can be excreted in semen.

Symptoms

Sows / Boars

• The infection can be subclinical.
• Bacteremia.
• Infertility.
• Abnormal estrus.
• Abortions at any stage.
• Vaginal discharges with pus or occasionally blood. 
• Late returns to estrus.
• Delayed returns to estrus.
• Lameness.
• Swollen / painful testicles

Lactating piglets

• Paralysis in hind legs.

Weaners and growers

• Swollen testicles.
• Lameness.

Causes / contributing factors

• Sexual transmission.
• The boar is the main transmission source, either by direct contact or by artificial insemination.
• Pigs can also get infected via the conjunctiva, nose or mouth.
• The North European hare can also get infected, and is considered a natural host.
• Carrier sows.

Diagnosis

Can be done through the isolation of the organism or by PCR. Serology is used to detect carrier sows although frequently crossed reactions with the bacteria Yersinia enterocolitica can be produced.

Control / prevention

• The treatment is not effective. Very little response to antibiotics.
• Depopulation of the farm.

Atlas of pathology