Brucella infection - including symptoms, treatment and prevention

This is a bacterial infection caused by a number of types of Brucella bacteria (Brucella abortus, B. melitensis, B. suis, and B canis). The bacteria are usually found in the below and can cause illness in these animals.

  • cattle
  • pigs
  • goats
  • sheep
  • working dogs
  • domestic animals.

B. abortus was successfully eradicated from cattle herds in Australia in 1989. B. melitensis and B. canis infections do not occur in Australia. Overseas travellers to areas where these infections are present may develop illness while overseas or on returning to Australia.

B. suis is found in some populations of feral pigs in Queensland and rarely spills over into domestic pigs. It remains a potential source of human infection in Australia.

Brucella infection is a notifiable condition1

How Brucella infection is spread

Brucella infection is mainly an occupational disease of farm workers, veterinarians and abattoir workers. The infection is spread by contact of breaks in the skin (open cuts or sores) with infected animal tissue or the ingestion of unpasteurised milk and dairy products from infected animals. The bacteria can also be inhaled in dusty animal enclosures, abattoirs and laboratories. Outbreaks can occur.

Signs and symptoms

Symptoms in humans include:

  • continuous or intermittent fever
  • headache
  • weakness
  • profuse sweats
  • chills
  • joint pains
  • aches
  • weight loss.

The infection can affect the liver and spleen, and may last for days or months, and sometimes for a year or more if not treated.

Joint complications and involvement of the testes and epididymis (storage tubes for sperm that are on top of the testes) are common. Recovery is usual but relapses can occur. Death can occur from inflammation of the lining of the heart (endocarditis) but this is very rare.

Diagnosis

Diagnosis is made by growing Brucella bacteria from the blood, bone marrow or other infected body tissues or from discharges from infected body tissues. Blood tests are also used to make the diagnosis.

Incubation period

(time between becoming infected and developing symptoms)

Variable. Usually 5 to 60 days, occasionally several months.

Infectious period

(time during which an infected person can infect others)

There is no evidence of person-to-person spread.

Treatment

People with Brucella infection can be treated with a combination of antibiotics, usually for at least 6 weeks. If relapse occurs, 3 months of antibiotic treatment is needed.

Prevention

  • Exclusion from work is not necessary.
  • A vaccine is not available for use in humans.
  • Control is best achieved by eliminating the disease in animals.
  • Avoid drinking raw or unpasteurised milk and products made from raw or unpasteurised milk.
  • Educate farmers, abattoir workers and other occupational at risk groups on how to prevent infection when handling potentially infected animal products:
    • cover open cuts and sores with dressings
    • wear gloves, overalls and face masks when slaughtering animals or handling animal products
    • thoroughly wash hands and arms after handling animals or their products
    • take special care when handling animal birth products
    • thoroughly clean all working areas

Useful links

1 – In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.