Overview

Brucellosis is an infectious disease caused by bacteria of the genus Brucella. It primarily affects animals such as cattle, goats, sheep, pigs, and dogs, but can be transmitted to humans, making it a zoonotic disease. Brucellosis is also known as undulant fever, Malta fever, or Mediterranean fever, due to its characteristic pattern of recurring fevers. In humans, it causes a range of symptoms, from mild flu-like illness to more severe, chronic conditions affecting various organs. While rarely fatal, brucellosis can lead to significant discomfort and long-term complications if not treated promptly. The disease is common in parts of the Middle East, South America, Africa, Asia, and the Mediterranean region.

Causes

Brucellosis is caused by infection with Brucella bacteria, which are transmitted from animals to humans through direct contact or consumption of contaminated animal products. The main species causing human infections include:

• Brucella melitensis: Found in goats and sheep; the most common and severe type affecting humans.
• Brucella abortus: Found in cattle.
• Brucella suis: Found in pigs.
• Brucella canis: Found in dogs.

Common modes of transmission to humans include:

• Consumption of unpasteurized milk, cheese, or other dairy products.
• Direct contact with infected animal tissues, blood, urine, or aborted fetuses, especially among farmers, veterinarians, and slaughterhouse workers.
• Inhalation of airborne bacteria in laboratories (occupational exposure).
• Rarely, person-to-person transmission through blood transfusions, organ transplantation, or sexual contact.

Symptoms

Symptoms of brucellosis can develop within 5 days to several months after exposure, typically appearing within 2-4 weeks. The disease can present as acute or chronic and affects multiple body systems.

Common Symptoms:

• Fever: Often intermittent or undulating (rising and falling), giving the disease its nickname "undulant fever".
• Chills and Sweating: Particularly noticeable at night, sometimes with a characteristic strong odor.
• Fatigue and Weakness: Persistent tiredness affecting daily activities.
• Muscle and Joint Pain: Common, especially in the back and large joints.
• Loss of Appetite and Weight Loss.
• Headaches.

Chronic Symptoms (if untreated or inadequately treated):

• Persistent low-grade fever.
• Arthritis or joint swelling.
• Neurological problems (neurobrucellosis), including depression or concentration difficulties.
• Endocarditis (infection of heart valves), which can be life-threatening.
• Liver or spleen enlargement.

Diagnosis

Diagnosing brucellosis requires a combination of clinical evaluation, history of exposure, and laboratory testing.

• Medical History: Doctors inquire about occupational exposure, consumption of unpasteurized dairy, or travel to endemic areas.
• Physical Examination: May reveal fever, joint tenderness, lymph node swelling, or organ enlargement.
• Blood Cultures: The gold standard for diagnosis; Brucella bacteria can often be cultured from blood samples.
• Serologic Tests: Detect antibodies against Brucella (e.g., Standard Agglutination Test).
• PCR Testing: Detects Brucella DNA in blood or tissues for faster diagnosis.
• Imaging Studies: X-rays, ultrasound, or MRI may be needed to assess joint, liver, spleen, or spinal involvement in complicated cases.

Treatment

Treatment of brucellosis involves a combination of antibiotics to eliminate the bacteria and prevent relapse.

• Antibiotic Regimen: The standard treatment includes doxycycline for at least 6 weeks combined with streptomycin for 2-3 weeks or rifampin for 6 weeks.
• Alternative Regimens: In children and pregnant women, alternative safer antibiotics are used.
• Management of Complications: Additional treatments, including prolonged antibiotics or surgery, may be required for conditions like endocarditis or neurobrucellosis.
• Supportive Care: Pain management, hydration, and rest are advised during recovery.

Prognosis

With appropriate treatment, the prognosis of brucellosis is generally good, though recovery may be slow.

• High Recovery Rate: Most patients recover completely with proper antibiotic therapy.
• Risk of Relapse: Relapse can occur in 5-15% of cases, typically within months of treatment completion, necessitating retreatment.
• Chronic Brucellosis: A small number of patients develop chronic symptoms, such as persistent fatigue and arthritis.
• Complications: If left untreated, brucellosis can lead to serious issues like endocarditis, infertility, or organ failure.
• Prevention: Preventive strategies include avoiding unpasteurized dairy products, using protective equipment during animal handling, and implementing veterinary control programs in livestock.

Early diagnosis and appropriate antibiotic therapy are key to reducing complications and achieving a complete recovery from brucellosis.