Brucellosis: Symptoms, Causes, Treatment, and Prevention

Overview

Brucellosis is a bacterial infection that primarily affects animals but can spread to humans. Also known as "Malta fever" or "undulant fever," it is caused by bacteria of the genus Brucella. The disease is rare in the United States, with fewer than 200 cases reported annually, but it remains a significant health concern in regions where animal vaccination programs are limited, such as parts of the Mediterranean, Middle East, Central Asia, and Latin America (CDC).

Brucellosis can affect people of all ages and genders, but it is most commonly seen in:

• Veterinarians, farmers, and ranchers
• Slaughterhouse workers
• Hunters
• Laboratory workers handling Brucella bacteria
• Travelers to endemic regions

The infection can become chronic if not treated promptly, leading to long-term complications.

Symptoms

Brucellosis symptoms can vary widely and may appear anywhere from a few days to several months after exposure. The disease often presents in phases, with symptoms that come and go. Common symptoms include:

Early Symptoms (Acute Phase)

• Fever: Often spikes in the afternoon or evening, accompanied by chills and sweating. The fever may rise and fall over weeks, giving the disease its nickname "undulant fever."
• Fatigue: Profound tiredness that doesn’t improve with rest.
• Muscle and joint pain: Particularly in the back, hips, and knees.
• Headache: Often severe and persistent.
• Loss of appetite and weight loss: Due to nausea, abdominal pain, or general malaise.
• Swollen lymph nodes: Especially in the neck, armpits, or groin.

Later Symptoms (Subacute or Chronic Phase)

If untreated, brucellosis can progress to a chronic form, with symptoms that persist for months or even years. These may include:

• Recurrent fevers: May come and go over long periods.
• Chronic fatigue: Debilitating exhaustion that interferes with daily life.
• Joint inflammation (arthritis): Particularly in the knees, hips, or spine. In some cases, it can lead to spondylitis (inflammation of the vertebrae).
• Swelling of the liver or spleen (hepatosplenomegaly): May cause abdominal discomfort or pain.
• Neurological symptoms: In rare cases, brucellosis can lead to meningitis (inflammation of the membranes around the brain and spinal cord) or encephalitis (brain inflammation). Symptoms may include severe headaches, confusion, seizures, or difficulty with coordination.
• Endocarditis: A serious infection of the heart’s inner lining, which can damage heart valves and lead to heart failure if untreated.
• Depression or mood changes: Chronic illness can contribute to mental health struggles.

Symptoms can be nonspecific and mimic other illnesses, such as the flu, tuberculosis, or Lyme disease, making diagnosis challenging.

Causes and Risk Factors

Causes

Brucellosis is caused by bacteria from the genus Brucella. There are several species that can infect humans, including:

• Brucella melitensis (most common and severe, typically from goats or sheep)
• Brucella abortus (from cattle)
• Brucella suis (from pigs)
• Brucella canis (from dogs)

The bacteria are primarily transmitted to humans through:

• Direct contact: Handling infected animal tissues, blood, urine, or birth products (e.g., placentas). The bacteria can enter the body through cuts, scrapes, or mucous membranes (eyes, nose, mouth).
• Consumption of contaminated food: Drinking unpasteurized (raw) milk or eating undercooked meat or dairy products from infected animals. This is the most common route of infection in endemic regions.
• Inhalation: Breathing in airborne bacteria, particularly in laboratories or slaughterhouses where Brucella is present.

Person-to-person transmission is extremely rare but can occur through sexual contact, breastfeeding, or blood transfusions.

Risk Factors

Certain factors increase the likelihood of contracting brucellosis:

• Occupation: People who work closely with animals or animal products, such as veterinarians, farmers, ranchers, slaughterhouse workers, and laboratory technicians, are at higher risk.
• Travel: Visiting or living in regions where brucellosis is common, such as the Mediterranean, Middle East, Central Asia, Mexico, or parts of South America.
• Dietary habits: Consuming raw or unpasteurized dairy products (e.g., milk, cheese) or undercooked meat from high-risk regions.
• Hunting: Handling or dressing wild game, such as elk, bison, or wild pigs, without proper precautions.
• Weakened immune system: Individuals with conditions like HIV/AIDS or those taking immunosuppressive medications may be more susceptible to infection.

Diagnosis

Diagnosing brucellosis can be challenging because its symptoms overlap with many other illnesses. A healthcare provider will typically begin with a detailed medical history, including questions about:

• Occupation and animal exposure
• Recent travel to endemic areas
• Dietary habits, particularly consumption of raw dairy or undercooked meat
• Symptom timeline and patterns (e.g., recurring fevers)

Diagnostic Tests

If brucellosis is suspected, the following tests may be used to confirm the diagnosis:

• Blood culture: The gold standard for diagnosis. A sample of blood is taken and cultured in a laboratory to isolate Brucella bacteria. However, this can take several weeks, as the bacteria grow slowly.
• Serologic tests: These tests detect antibodies produced by the immune system in response to Brucella infection. Common serologic tests include:
  • Rose Bengal test: A rapid screening test that detects antibodies in the blood.
  • Enzyme-linked immunosorbent assay (ELISA): Measures the level of specific antibodies to Brucella.
  • Agglutination tests (e.g., tube agglutination test): Measures how antibodies in the blood clump together in response to Brucella antigens.
• Polymerase chain reaction (PCR): A molecular test that detects Brucella DNA in blood or tissue samples. This test is faster than blood cultures but may not be widely available.
• Bone marrow culture: In chronic or complicated cases, a bone marrow sample may be cultured to detect the bacteria, as they can persist in bone marrow even after blood cultures become negative.
• Imaging tests: X-rays, CT scans, or MRI may be used to assess complications such as joint inflammation, liver or spleen enlargement, or spinal infections.

Diagnosis often requires a combination of tests, as no single test is 100% accurate. A healthcare provider will interpret results in the context of the patient’s symptoms and exposure history.

Treatment Options

Brucellosis is treatable with antibiotics, but the infection can be difficult to eradicate completely. Treatment typically involves a combination of antibiotics taken for at least 6 weeks to prevent relapse. Common antibiotic regimens include:

• Doxycycline + Rifampin: This is the most commonly recommended combination. Doxycycline is taken for 6 weeks, while rifampin is taken for at least 6–8 weeks. This regimen is effective for most cases of uncomplicated brucellosis.
• Doxycycline + Streptomycin: Streptomycin is an injectable antibiotic given for the first 2–3 weeks, followed by doxycycline for an additional 4–6 weeks. This combination is often used for more severe infections or complications like endocarditis.
• Alternative regimens: For patients who cannot tolerate doxycycline (e.g., children or pregnant women), combinations such as rifampin + trimethoprim-sulfamethoxazole or rifampin + ciprofloxacin may be used.

Treatment Considerations

• Duration: Treatment must be completed for the full duration prescribed, even if symptoms improve, to prevent relapse. Chronic brucellosis may require longer courses of antibiotics (e.g., 3–6 months).
• Side effects: Antibiotics can cause side effects such as nausea, diarrhea, or sun sensitivity (with doxycycline). Rifampin can turn urine, sweat, or tears orange-red, which is harmless.
• Follow-up: Regular follow-up with a healthcare provider is essential to monitor response to treatment and check for relapse. Blood tests may be repeated to ensure the infection is clearing.
• Hospitalization: Severe cases, especially those with complications like endocarditis or meningitis, may require hospitalization for intravenous antibiotics and supportive care.

Supportive Care

In addition to antibiotics, supportive measures can help manage symptoms:

• Rest: Adequate rest is crucial, especially during acute phases of fever and fatigue.
• Hydration: Drink plenty of fluids to prevent dehydration from fever and sweating.
• Pain relief: Over-the-counter pain relievers like acetaminophen (Tylenol) or ibuprofen (Advil) can help reduce fever, headaches, and muscle pain. Avoid aspirin in children due to the risk of Reye’s syndrome.
• Physical therapy: For patients with chronic joint pain or arthritis, physical therapy may help improve mobility and reduce discomfort.

Living with Brucellosis

Recovering from brucellosis can be a long process, especially if the infection becomes chronic. Here are some tips for managing daily life during and after treatment:

Managing Fatigue

• Prioritize rest: Listen to your body and rest when needed. Fatigue can be debilitating, so pace yourself and avoid overexertion.
• Gradual activity: Once symptoms improve, slowly reintroduce light activities like walking or stretching. Avoid high-intensity exercise until cleared by a healthcare provider.
• Balanced diet: Eat nutrient-rich foods to support recovery. Focus on lean proteins, whole grains, fruits, and vegetables. Small, frequent meals may help if appetite is poor.

Coping with Chronic Pain

• Heat or cold therapy: Apply heating pads or ice packs to sore joints or muscles for relief.
• Gentle exercise: Low-impact activities like swimming or yoga can help maintain mobility without straining joints.
• Pain management: Work with a healthcare provider to find the safest and most effective pain relief options, especially if chronic arthritis develops.

Mental Health Support

• Seek support: Chronic illness can take a toll on mental health. Consider talking to a therapist or joining a support group for people with chronic infections.
• Stay connected: Maintain social connections with friends and family to combat feelings of isolation.
• Mindfulness and relaxation: Techniques such as meditation, deep breathing, or guided imagery can help reduce stress and improve overall well-being.

Preventing Relapse

• Complete treatment: Finish the full course of antibiotics as prescribed, even if you feel better.
• Follow-up appointments: Attend all scheduled follow-up visits to monitor for relapse or complications.
• Avoid re-exposure: Take precautions to prevent reinfection, especially if you work with animals or travel to endemic areas.

Prevention

Preventing brucellosis involves reducing exposure to Brucella bacteria. Here are key strategies:

For Animal Workers and Hunters

• Use protective equipment: Wear gloves, goggles, and protective clothing when handling animals, animal tissues, or birth products.
• Practice good hygiene: Wash hands thoroughly with soap and water after contact with animals or animal products. Use disinfectants to clean work surfaces and tools.
• Vaccinate animals: If you raise livestock, work with a veterinarian to implement a Brucella vaccination program for your animals.
• Safe disposal: Properly dispose of animal carcasses, placentas, and other potentially contaminated materials.

For Travelers

• Avoid raw dairy: Do not consume unpasteurized milk, cheese, or other dairy products in regions where brucellosis is common.
• Cook meat thoroughly: Ensure all meat is cooked to safe temperatures (at least 145°F for whole cuts, 160°F for ground meat).
• Be cautious with street food: Avoid foods that may contain raw or undercooked ingredients, such as certain traditional dishes or fresh cheeses.

For Laboratory Workers

• Follow biosafety protocols: Handle Brucella samples in a Biosafety Level 3 (BSL-3) laboratory with appropriate containment measures.
• Use personal protective equipment (PPE): Wear gloves, lab coats, and face protection when working with potentially infectious materials.
• Proper disposal: Autoclave (sterilize) all contaminated materials before disposal.

General Precautions

• Educate yourself: Learn about the risks of brucellosis if you live in or travel to endemic areas.
• Report symptoms: If you develop symptoms after potential exposure, seek medical attention promptly and inform your healthcare provider about your risk factors.
• Public health measures: Support and comply with public health efforts to control brucellosis in animals, such as vaccination and surveillance programs.

Complications

If left untreated, brucellosis can lead to serious and sometimes life-threatening complications. These may include:

• Chronic brucellosis: Up to 10–30% of untreated cases become chronic, with symptoms lasting for years. Chronic brucellosis can cause persistent fatigue, joint pain, and recurrent fevers.
• Endocarditis: Infection of the heart’s inner lining, which can damage heart valves and lead to heart failure. Endocarditis occurs in about 1–2% of brucellosis cases and is a leading cause of death from the disease.
• Arthritis: Joint inflammation, particularly in the knees, hips, or spine, can become chronic and debilitating. Spondylitis (inflammation of the spine) is a common complication.
• Neurological complications: Brucellosis can lead to meningitis, encephalitis, or inflammation of the nerves (neuritis). Symptoms may include severe headaches, confusion, seizures, or weakness.
• Hepatitis: Inflammation of the liver, which can cause jaundice (yellowing of the skin and eyes), abdominal pain, and elevated liver enzymes.
• Splenic abscesses: Pus-filled pockets in the spleen, which may require surgical drainage.
• Reproductive issues: In men, brucellosis can cause epididymo-orchitis (inflammation of the testicles and epididymis). In women, it can lead to miscarriage, premature birth, or infection of the placenta.
• Osteomyelitis: Bone infection, which can cause severe pain and may require long-term antibiotic treatment or surgery.

Early diagnosis and treatment are critical to preventing these complications. If you suspect you have been exposed to Brucella or are experiencing symptoms, seek medical attention promptly.

When to Seek Emergency Care

References and Further Reading

• Centers for Disease Control and Prevention (CDC) – Brucellosis
• Mayo Clinic – Brucellosis
• World Health Organization (WHO) – Brucellosis
• National Institutes of Health (NIH) – Brucellosis
• Cleveland Clinic – Brucellosis