Background Information

What is brucellosis?

Brucellosis is a highly transmissible zoonosis (human infection of animal origin) caused by bacteria of the genus Brucella. Brucellosis affects a wide variety of mammals; in humans the disease is also known as undulant fever or Mediterranean fever. Human infections arise through direct contact with infected animals or their milk.

What is its bioterrorism potential?

Brucella is highly infectious by the airborne route and could be used in an aerosolised form or as a contaminant of food, milk and water. The organism survives well in the environment and widespread contamination is possible. Human infection is rarely fatal but brucellosis can be a protracted debilitating illness often requiring prolonged antibiotic treatment. Although animal vaccines are available, there are no effective human vaccines.

How do you catch brucellosis?

Human infections usually arise from direct contact with infected animals or their milk. Infection is through ingestion (unpasteurised milk and milk products), inhalation (aerosols) or direct inoculation (usually in those with an occupational exposure such as veterinarians or farmers).

How long can you have the infection before developing symptoms?

Incubation is variable, typically 5-30 days, but may be up to 6 months. The infection may persist for several months without causing any symptoms.

What are the symptoms?

The major features are prolonged fever and debilitation, weight loss, sweating, headache, lethargy, anorexia and joint pains. Acute disease lasts for weeks, and although a substantial minority will have self-limiting disease, some people develop long-lasting or chronic disease with relapsing infection that may last for years with malaise, depression and destructive arthritis/ osteomyelitis. If left untreated up to 2% of patients will develop endocarditis which can be fatal.

How can brucellosis be treated?

Brucellosis is usually treated with a combination therapy of doxycycline and rifampicin for a minimum of six weeks. Treatment failure or relapse may occur due to inadequate duration or dose of therapy. Follow-up for a minimum period of a year is essential to encourage patient adherence to the chemotherapy regimen and to detect relapse.

How can brucellosis be prevented?

Brucellosis can be prevented by controlling and eradicating disease in animals and by pasteurising milk. Visitors to countries where the disease is endemic should be advised not to consume unpasteurised milk or milk products.

There is no vaccine available for humans in the UK. In the event of a release of Brucella exposed individuals can be treated with antibiotics. Person-to-person spread of Brucella species is rare therefore there is no specific treatment or advice required for secondary contacts.

How common is brucellosis?

Brucella species are widespread throughout the world. However, brucellosis is rare in the UK and with the exception of some cattle-associated cases in Northern Ireland all cases are acquired abroad.

Last reviewed: 11 June 2010