Brucellosis

What is brucellosis?
Brucellosis is a highly infectious disease caused by the bacteria of the genus Brucella. It primarily affects animals such as sheep, goats, cattle, camels, deer, pigs, and dogs.

Brucella melitensis, Brucella abortus and Brucella suis are the main species that cause disease in man.

How common is brucellosis?
It is estimated that there are about two million cases of brucellosis infections every year. Brucellosis is common in certain parts of the world, especially the Mediterranean region. In 2021, 165 cases were reported in the EU/EEA region.

Brucellosis is a notifiable disease in Ireland.

Since 2018, only one case of brucellosis has been notified in Ireland. In the UK, most cases are acquired overseas and the same is likely true of any Irish cases. In 2009, the Minister of Agriculture, Food and the Marine confirmed that Ireland had been declared brucellosis free.

People who handle animals as part of their work, like butchers, farmers, laboratory personnel, veterinarians, etc. are at an increased risk of contracting brucellosis.

How is brucellosis spread?
Humans become infected by coming in contact with animals or animal products that are contaminated with the bacteria, through the following ways:

• Eating or drinking contaminated or unpasteurised milk and milk products (the most common way)
• Eating inappropriately cooked or raw meat
• Getting skin wounds, especially if you are a farmer, veterinarian or work in meat processing

Very rarely, brucellosis may be spread through breast feeding and sexual contact.

Direct person-to-person spread of brucellosis is extremely rare.

What are the symptoms of brucellosis?
In humans, brucellosis can cause a range of symptoms that are like flu and may include:

• Fever
• Sweating
• Headaches
• Back and joint pain
• General malaise (feeling unwell).

Occasionally, severe infection of the nervous system or heart can occur.

Untreated, brucellosis symptoms can recur over many years and can also cause chronic symptoms that include recurrent fevers, joint pain, intermittent fever and fatigue.

See your GP if you’ve had these symptoms and:

• Work with farm animals
• Have consumed unpasteurised dairy products
• Eaten undercooked or raw meat
• Travelled overseas recently.

How is brucellosis diagnosed?
Brucellosis is diagnosed by detecting Brucella in samples of blood or bone marrow. Blood tests can also identify antibodies to Brucella, indicating infection.

What is the treatment for brucellosis?
Brucellosis is treated with antibiotics. The standard treatment involves a combination of doxycycline and rifampin for at least six weeks. Recurring infection may require longer courses or a change of antibiotics.

Depending on the timing of treatment and severity of illness, recovery may take a few weeks to several months.

Can brucellosis be prevented?
Currently, there are no vaccines available for human brucellosis.

To protect yourself:

• Avoid unpasteurised milk and dairy products (including soft cheeses and ice cream)
• Avoid raw or undercooked meat
• Use protective equipment (gloves, gowns, goggles) if working with animals or animal products
• Cover any open wounds when handling animals
• Follow safe food-handling and hygiene practices
• Be cautious when traveling to areas where brucellosis is common.

Last updated: 6 June 2025