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11 September 2023

Causative agent

Brucellosis is an infectious disease caused by the bacteria of the genus Brucella. These bacteria primarily infect animals, such as cattle, dogs, pigs, sheep and goats.

Clinical features

The symptoms of brucellosis are nonspecific. They include fever, sweat, malaise, anorexia, headache, pain in muscles, joint, and/or back, fatigue, loss of appetite, and weakness. Severe infections may affect the brain, heart, liver, spleen, other organs or body systems. The disease may progress to a chronic one and persist for years. Relapses may occur after treatment.

Mode of transmission

Brucellosis can be transmitted to humans from infected animals or contaminated animal products through the following ways:

  • Consume contaminated products, including unpasteurised dairy products, raw or undercooked meat or internal organs.
  • Contact through breaks in the skin or mucous membrane with infected animal tissues, blood, urine, vaginal discharges, aborted foetuses, and placentas.
  • Inhale contaminated aerosols.

Direct human-to-human spread is rare.

High risk groups

People who are occupationally exposed to infected animals or their tissues, such as slaughterhouse workers, meat-packing workers, veterinarians and laboratory workers, are relatively at high risk of contracting brucellosis. In Hong Kong, brucellosis is a notifiable occupational disease.

Incubation period

The incubation period is usually 2 to 4 weeks but can range from 5 days to 6 months


Brucellosis can be treated by antibiotics. 


Vaccine is available for animals only. To prevent the infection, members of the public are urged to observe good personal and food hygiene.

1. Maintain good personal hygiene

  • Perform hand hygiene frequently. Wash hands thoroughly with liquid soap and water after having contacts with animals or their secretions.
  • Clean the broken skin immediately and cover properly with waterproof adhesive dressings. Wash hands before and after touching wounds.
  • Wear appropriate protective equipment, including mask, gloves, goggle and gown or apron, when handling animal tissues or internal organs especially for those who are exposed occupationally. Wash hands thoroughly afterwards.

2. Maintain good food hygiene

  • Do not consume unpasteurised dairy products, raw or undercooked meat and internal organs.
  • Adopt the 5 Keys to Food Safety in handling food, i.e. Choose (Choose safe raw materials); Clean (Keep hands and utensils clean); Separate (Separate raw and cooked food); Cook (Cook thoroughly); and Safe Temperature (Keep food at safe temperature) to prevent foodborne diseases.

Please visit the website of Centre for Food Safety for more information on food safety.