Key facts

Brucellosis, also known as “undulating fever” or “Mediterranean fever”, is a zoonotic disease caused by bacteria of the genus Brucella, primarily affecting livestock like cattle, sheep, goats, and pigs. The most common species causing human infection are Brucella melitensis (which is the most common), Brucella abortus, Brucella suis, and Brucella canis.
Brucellosis is present worldwide, especially in regions where livestock management and veterinary services are underdeveloped, including parts of Africa, the Mediterranean, the Middle East, and Latin America.
Humans can acquire Brucellosis through direct contact with infected animals, their tissues, or by consuming contaminated animal products, such as unpasteurized milk or cheese.

Transmission

Consuming raw or unpasteurized dairy products, including milk, cheese, and butter, made from infected animals.
Handling infected animal tissues, organs, blood, urine, or placentas, particularly during slaughter, veterinary procedures, or meat processing.
Inhaling airborne bacteria, which can occur in laboratory settings, during handling of infected animals
Environmental exposure in areas with high levels of animal waste.
From an infected mother to her child during childbirth or through breastfeeding.
Person-to-person is not common

Most Vulnerable to Contracting the Disease

Individuals working in frequent contact with animals or animal products, such as farmers, veterinarians, abattoir workers, and laboratory personnel.
Consumers of unpasteurized dairy
Travelers to or living in endemic areas.

Signs and symptoms

In animals

Typically, the sign of the disease in animals is not evident until reproductive signs occur
Abortion in infected pregnant female animals (sometimes) or some may give birth to give birth to weak and vulnerable animals.
Swelling of the testicles in males (sometimes)
Arthritis (sometimes)
In horses, there may be a swelling of the neck or back (called fistulous withers or poll evil) Infected pregnant mares may either abort

Note: One of the most important implications of brucellosis is that it causes poor reproductive performance, due to abortions, infertility, retention of placenta, stillbirth or birth of weak offspring. This results in huge economic losses to dairy, sheep, goat and pig farmers.

In humans

Acute Phase
- Fever, often fluctuating (undulant fever)
- Sweating, particularly at night
- Fatigue and general weakness
- Muscle and joint pain
- Headaches
Chronic Phase
- Persistent or recurrent fevers
- Arthritis and joint pain
- Swelling of the testicles and scrotum area
- Neurological symptoms such as depression, fatigue, and headaches

What can you do to prevent and control an epidemic?

The most effective prevention strategy is the elimination of infection in animals.
Monitoring the community and identifying sick people and animals
- Detect sick people and animals quickly for referral to the appropriate health facilities
- Monitor the community for clusters of sick or dead animals
  - Report any clusters to your supervisor, animal health and welfare authorities and/or health authorities
  - Encourage quarantining sick animals from healthy ones
    - Discourage community members from taking sick animals to markets or other places where they may encounter other animals or humans
  - Encourage minimal contact between sick animals and humans
  - Limit contact between sick and healthy animals, stop sick animals from reaching the market, etc.)

Treatment and management

Vaccination of cattle, goats and sheep is recommended in areas with high prevalence rates of the disease among the animal populations.
Refer suspected human and animal cases for screening and treatment
- Refer people to the appropriate health facilities
- Notify animal health and welfare authorities and professionals or care providers (such as veterinarians) of suspected cases in animals
If antibiotic and supportive treatment is available (for animals or people), encourage people to seek and complete treatment as directed by health care providers
Provide psychosocial support to the sick person and their family members

Safe animal handling

Safe handling and slaughtering practices including supervision and meat inspection
People working with animals or animal products should wear protective clothing and equipment and follow recommended hygiene practices

Personal protection and hygiene

Promote handwashing with soap
- BEFORE: preparing food; eating; feeding a child; treating wounds; or caring for sick people
- AFTER: using the toilet or cleaning a baby; touching garbage or waste (especially when dealing with rodent waste); touching or feeding animals; blowing nose, coughing or sneezing; treating wounds; or caring for sick people
In agricultural work and meat-processing, workers should wear protective clothing and ensure correct handling and disposal of afterbirths, animal carcasses and internal organs

Food and water hygiene and safety

Cook animal products thoroughly (including meat, milk and offal).
Boil/heat milk before drinking it to kill harmful germs and prevent disease that can spread from animals to humans.

Social mobilisation and health promotion

In countries where eradication in animals through vaccination or elimination of infected animals is not feasible, prevention of human infection is primarily based on raising awareness, food-safety measures, occupational hygiene and laboratory safety.
Establish education campaigns about avoiding raw, untreated and unsafe milk products.
Find out the specific advice being given by health and other relevant animal health authorities
- Liaise with health professionals in both human and animal health sectors for health advice and promotion messages for best health practices.
- Promote recommended health practices (such as safe animal handling and use of protective clothing and equipment)
Model following this advice and inform community members of current health practice advice 
Offer support and encouragement to people to help them follow the advice  
- Try to gain understanding about if and why health advice is not being followed  
- With the advice of your supervisor and health authorities, work with communities to overcome barriers to following health advice and recommended practices

Mapping and community assessment

Make a map of the community.
Mark the following information on the map:
- How many people and animals have fallen sick with brucellosis? Where?
- How many people have died? Where? When?
- How many animals have died? Where? When?
- Who and where are the vulnerable people? (where are farms, slaughterhouses, wool mills, etc?)
- Where are the handwashing facilities in the community? (are there stations at animal markets and other areas where livestock gather?)
  - Are soap and water always available?
- Where are the local health facilities and services? (include traditional healers)
Record the following information on the back of the map:
- When did people and animals start to fall sick with brucellosis?
- How many people live in the affected community? How many are children under five years of age? How many people work with livestock regularly?
- Do people cook meat and milk thoroughly before eating it?
- Do any animal health agencies, veterinarians or agriculture ministry agencies work in the area?
- What are the community’s habits, practices and beliefs about caring for and feeding sick people?
- What are the community’s habits, practices and beliefs about care and slaughter of animals?
  - Are there societal, cultural or religious beliefs or perceptions about the care and slaughter of animals?
- What are the community’s habits, practices and beliefs about sick or dead animals?
  - How do people dispose of animal carcasses (by burning, burying, eating, etc.)?
- Is a social mobilisation or health promotion programme in place?
- Which sources do people use/trust the most for information?
  - Are there rumours or misinformation about brucellosis? What are the rumours?
- What role do women play in livestock management (including caring for animals, gathering animal feed and selling animal products in markets)?

Volunteer actions

01. Community-based surveillance 02. Community mapping 03. Communicating with the community 04. Community referral to health facilities 19. Psychosocial support 29. Hygiene promotion 31. Good food hygiene 32. Sanitation 33. Encouraging the use and maintanace of latrines 34. Handwashing with soap 41. Handling and slaughtering animals 43. Social mobilization and behaviour change 44. Dealing with rumors

Other resources

World Health Organization (WHO); Brucellosis; 2020
World Health Organization (WHO); Brucellosis in Humans and Animals; 2006
https://www.who.int/publications/i/item/9789241547130
Centers for Disease Control and Prevention (CDC); About Brucellosis; 2024
World Organisation for Animal Health (WOAH); Brucellosis. (n.d.)
World Organisation for Animal Health (WOAH); Brucellosis; 2022