Swine brucellosis

B. suis has been detected in feral pigs in the Northern Territory (NT).

It's widespread in Queensland's feral pig population, and has also been detected in the feral pig population in northern New South Wales.

Other species of the Brucella bacteria can cause different types of brucellosis.

Australia is free of Brucella abortus, Brucella melitensis and Brucella canis.

Bovine brucellosis is caused by Brucella abortus and was eradicated from Australia in 1989 as a result of a national eradication program.

Control of B. suis in feral pigs isn't possible, and treatment of domestic pigs is not considered practical.

Treatment for infected dogs includes a long course of antibiotic therapy and desexing to reduce the risk of spread to people or other animals. Treatment is not always successful, and in some cases dogs will relapse.

Humans are treated with extended courses of antibiotics.

You should monitor for the following signs.

Pigs

Pigs will general show signs of:

• reproductive failure
• piglet mortality
• swollen testicles.

Dogs

Dogs can remain bright, alert and show no obvious signs of infection.

Clinical signs include:

• fever
• swollen testicles
• back pain
• lameness
• vomiting
• lethargy
• haematuria
• abortion.

Cattle and horses

Cattle and horses may pick up infection from open waters used by feral pigs.

There are no specific clinical signs associated with B. suis infection.

However, both cattle and horses may react positively to brucellosis testing due to infection with B. suis.

A positive test result for brucella in cattle during a herd fertility test, must be investigated to ensure that it has not been caused by brucella abortus (bovine brucellosis), which is exotic to Australia.

Humans

The incubation period in people is variable from 5 days to months, but averages 2 weeks.

Weakness, fatigue and exhaustion are common with fever, head and body pains and mental depression.

Anyone who suspects they may have been infected with B. suis should contact their doctor.

Recovery can take up to 12 months, but antibiotics shorten the disease course.

Spread

The main source of infection is infected pigs.

Boars can pass the disease on during mating. Spread can also occur by the ingestion of food and water contaminated with:

• urine
• placenta
• discharges from infected sows.

The organism can survive in faeces, urine and water for 4 to 6 weeks and much longer in freezing conditions.

Direct sunlight will kill the organism quickly.

Dogs

Infected dogs are a potential source of infection for people through contact with urine, saliva and reproductive materials.

Dogs may also act as mechanical carriers by shedding Brucella in the faeces after ingesting infected aborted foetuses or placentas.

Humans

In humans, B. suis mainly affects:

• abattoir workers
• pig farmers
• feral pig shooters.

Humans can contract the disease through skin, conjunctiva and by ingestion.

Killing and slaughter of feral pigs can increase the risk of human infection unless strict hygiene measures are taken.

Infection can occur from contaminated meat during preparation, cooking and serving of feral pig meat.

Veterinarians can submit:

• whole blood or serum for serology
• fresh, chilled tissue
  • eg. entire testicle, uterus or aborted foetuses for bacterial culture.
  • note: can't differentiate between specific species of Brucella. 

Tissue specimens should not be sliced open as this may increase the risk of human infection.

Label clearly 'Brucella exclusion'.

All samples are double bagged and any paperwork is outside the sample container.

Prevent the entry of feral or other infected pigs onto your property.

If you notice reproductive disease or swollen testicles in your pigs, contact a veterinarian.

When handling pigs you should:

• cover all cuts and abrasions with waterproof dressings
• wear enclosed waterproof footwear
• use good personal hygiene
• wash your hands regularly.

Safe handling practices

Use personal protective equipment (PPE) including gloves and eye protection when:

• handling pregnant or sick pigs
• butchering pigs.

When hunting:

• cover all cuts and abrasions with waterproof dressings
• wear enclosed waterproof footwear
• use good personal hygiene
• wash your hands regularly.

Clean and disinfect work areas and vehicles after a hunt.

If butchering feral pigs take extra precautions including wearing gloves and eye protection. If a pig looks sick, don't handle or butcher it.

Always cook game meat thoroughly.

Don't feed raw feral pig meat to your dogs.

When handling pigs and pig hunting dogs you should use good personal hygiene and wear:

• PPE
• including gloves and eye protection.

Particular care should be taken when:

• treating wounds
• collecting blood
• neutering
• assisting with whelping or reproductive problems
• performing caesareans on pig hunting dogs.

A safe work method statement for collecting samples for B suis testing is available from the NSW Department of Industry website.