Brucellosis

Brucellosis is a bacterial infection caused by Brucella bacteria, usually acquired from infected animals or unpasteurized milk and dairy products. It can cause fever, sweats, fatigue and body aches, and it usually requires specialist diagnosis and antibiotic treatment.

Overview

Brucellosis is an infectious disease caused by bacteria of the genus Brucella. It is mainly a zoonotic disease, which means the bacteria naturally infect animals and can spread to humans. The animals most often involved include goats, sheep, cattle, pigs, dogs and camels, although the exact source may vary by region.

People most commonly acquire brucellosis by consuming unpasteurized milk, cheese or other dairy products made from infected animals. Infection can also occur when Brucella bacteria enter the body through cuts in the skin, the eyes or mucous membranes, or when contaminated particles are inhaled in laboratories, farms, slaughterhouses or veterinary settings.

Brucellosis may develop gradually and can resemble many other illnesses. It often causes fever, sweating, fatigue and aches that come and go. Because symptoms can be non-specific, a careful history of food exposure, animal contact, travel and occupation is an important part of diagnosis.

With timely diagnosis and appropriate antibiotic treatment, many people recover well. However, brucellosis can persist or return if it is not treated adequately, so care from a qualified doctor or infectious diseases specialist is important.

Symptoms

Brucellosis symptoms can appear a few days to several weeks after exposure, and sometimes later. The illness may begin suddenly or develop slowly. A characteristic pattern is fever that may rise and fall, often accompanied by heavy sweating, especially at night.

Common brucellosis symptoms include:

• Fever or recurrent episodes of fever
• Night sweats, sometimes with a strong odor
• Fatigue, weakness or reduced stamina
• Headache
• Muscle aches and joint pain
• Back pain
• Loss of appetite or unintentional weight loss
• Chills or general malaise

Some people develop symptoms related to specific organs. These may include abdominal discomfort, enlarged liver or spleen, testicular pain or swelling in men, persistent back pain, or inflammation around joints. Rarely, brucellosis can affect the heart, nervous system or bones, which requires urgent specialist care.

Because brucellosis can mimic influenza, tuberculosis, rheumatologic disorders and other infections, symptoms alone are not enough to confirm the condition. Medical testing is needed, especially when symptoms follow animal contact, work with livestock, travel to an endemic area, or intake of unpasteurized dairy products.

Causes & Risk Factors

Brucellosis is caused by Brucella bacteria. Different Brucella species are associated with different animals, such as goats and sheep, cattle, pigs and dogs. In humans, infection occurs when bacteria enter the body through the digestive tract, broken skin, mucous membranes or the respiratory system.

The most common cause worldwide is eating or drinking contaminated unpasteurized dairy products. Pasteurization is a heat-treatment process that kills harmful bacteria while preserving the food for consumption. Fresh cheeses, raw milk and dairy products from informal or unregulated sources may carry higher risk in areas where animal brucellosis is present.

Occupational exposure is another important risk factor. People who work closely with animals or animal tissues may have increased risk, including farmers, shepherds, veterinarians, abattoir workers, meat-processing workers, laboratory staff and hunters. Infection can occur through contact with animal blood, birth fluids, placentas, aborted fetuses or contaminated equipment.

Risk is also influenced by geography and travel. Brucellosis is more common in regions where animal vaccination, food safety controls or pasteurization practices are limited. Person-to-person spread is very uncommon, so most prevention focuses on safe food practices, animal health programs and workplace protection.

Diagnosis

Brucellosis diagnosis begins with a medical history and physical examination. The doctor will ask about fever patterns, night sweats, joint or back pain, travel, consumption of unpasteurized dairy products, animal exposure and occupation. This information helps decide which tests are appropriate.

Blood tests are commonly used. Blood cultures may detect Brucella bacteria, although results can take time because the organism may grow slowly. Serology tests look for antibodies produced by the immune system in response to Brucella infection. In some situations, repeated testing may be needed to show a rising antibody level or to clarify uncertain results.

Additional tests may be recommended depending on symptoms. These can include complete blood count, liver function tests, inflammatory markers, urine tests or cultures from other body fluids. If bone, joint, spine, heart or nervous system involvement is suspected, imaging studies such as ultrasound, echocardiography, CT or MRI may be considered by the specialist.

Accurate diagnosis is important because brucellosis treatment differs from treatment for many other causes of fever. A doctor interprets laboratory findings together with exposure history and clinical features, rather than relying on a single result alone.

Treatment Options

Brucellosis treatment usually involves antibiotics that can reach the bacteria effectively and reduce the chance of relapse. Treatment often requires more than one antibiotic and is typically continued for several weeks. The exact choice and duration depend on the patient’s age, pregnancy status, allergy history, disease severity, organ involvement and local medical guidance.

The right approach is decided by a qualified doctor, often an infectious diseases specialist, after assessment. Patients should not stop treatment early, change doses or use leftover antibiotics, because incomplete treatment can allow symptoms to return and may complicate recovery. Follow-up visits are important to check response and monitor for side effects.

If brucellosis affects specific organs, additional care may be needed. Bone and joint involvement may require imaging, pain control, physiotherapy or orthopedic input. Heart valve infection, nervous system involvement, abscess formation or severe complications may require hospital care and multidisciplinary management. Surgery is uncommon but may be considered in selected complicated cases, such as persistent abscesses or serious heart valve disease.

Supportive care also plays a role. Rest, hydration, nutrition and gradual return to activity can help recovery from fatigue and weakness. Any persistent or worsening symptoms during treatment should be discussed promptly with the treating doctor.

Living With / Prognosis

Many people with brucellosis improve with appropriate antibiotic treatment and follow-up. Fever and sweats may settle before fatigue and body aches fully resolve, so recovery can be gradual. Some patients need time to regain normal energy levels, especially if symptoms were present for weeks or months before diagnosis.

Relapse can occur, particularly when treatment is delayed, shortened or complicated disease is present. Relapse usually means symptoms return after a period of improvement and should be assessed medically rather than self-treated. Follow-up testing and review may help the doctor determine whether further treatment or evaluation is needed.

Prevention is an important part of living safely in areas where brucellosis occurs. People should avoid unpasteurized milk and dairy products, choose regulated food sources, wear protective gloves and equipment when handling animals or animal tissues, and follow workplace safety procedures. Farmers and animal-health professionals may also reduce risk through veterinary control programs and safe handling of animal births and abortions.

For international patients, Acibadem International’s multidisciplinary specialists and JCI-accredited hospitals can diagnose and treat brucellosis and its complications within an evidence-based care pathway. As with all infectious diseases, individualized medical assessment is essential.

When to See a Doctor

A person should see a doctor if they develop persistent or recurring fever, night sweats, unusual fatigue, joint pain or back pain after consuming unpasteurized dairy products, handling livestock, working in a veterinary or slaughterhouse setting, or traveling to an area where brucellosis is known to occur.

Medical attention is especially important if symptoms last more than a few days without a clear cause, return after seeming to improve, or are accompanied by weight loss, abdominal swelling, testicular pain, severe headache, confusion, chest pain or shortness of breath. These features do not always mean a serious complication is present, but they require prompt evaluation.

People who are pregnant, immunocompromised, elderly, or living with chronic heart, liver or kidney disease should seek advice early if brucellosis exposure is possible. Children with unexplained fever and relevant exposure should also be assessed by a pediatrician.

Anyone being treated for brucellosis should contact their doctor if fever persists, side effects occur, or medication is missed. Safe and effective care depends on completing the recommended course and attending follow-up appointments.

Frequently asked questions

What is brucellosis?

Brucellosis is a bacterial infection caused by Brucella species. It usually spreads from infected animals to humans through unpasteurized dairy products, direct animal contact or inhalation of contaminated particles. It commonly causes fever, sweats, fatigue and body aches.

How do people get brucellosis?

People most often get brucellosis by eating or drinking unpasteurized milk, cheese or other dairy products from infected animals. It can also enter through cuts in the skin, the eyes or the mouth during contact with infected animals or animal tissues. Some workers may inhale contaminated particles in laboratories, farms or slaughterhouses.

Is brucellosis contagious from person to person?

Person-to-person spread of brucellosis is very rare. Most infections come from animals, animal products or occupational exposure. Routine social contact with a person who has brucellosis is not considered a common route of infection.

What are the main brucellosis symptoms?

The main symptoms are fever, night sweats, fatigue, weakness, headache, muscle pain and joint pain. Symptoms may come and go, which can delay diagnosis. Some people may also develop back pain, weight loss, abdominal discomfort or organ-specific complications.

How is brucellosis diagnosed?

Diagnosis is based on symptoms, exposure history and laboratory tests. Doctors may use blood cultures, antibody tests and general blood tests, and sometimes imaging if bones, joints, heart or nervous system involvement is suspected. Results should be interpreted by a qualified clinician because brucellosis can resemble other illnesses.

Can brucellosis be cured?

Many people recover with appropriate antibiotic treatment prescribed by a doctor. Treatment usually requires a combination of antibiotics for several weeks to reduce the risk of relapse. Follow-up is important because symptoms can return if the infection is not fully controlled.

How can brucellosis be prevented?

Prevention includes avoiding unpasteurized milk and dairy products, choosing regulated food sources, and using protective equipment when handling animals or animal tissues. People working with livestock, animal births or laboratory samples should follow workplace safety protocols. Animal vaccination and veterinary control programs also help reduce human risk.

References

• World Health Organization
• Centers for Disease Control and Prevention
• European Centre for Disease Prevention and Control
• Merck Manual Professional Edition
• Mayo Clinic

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.