Makindo Medical Notes

🧬 Brucella species mainly infect cattle, swine, goats, sheep, and dogs. 🥛 Most human cases are due to ingestion of unpasteurised milk, cheese, or dairy products (especially from goats or sheep). ⚠️ It is one of the world’s most common zoonoses, sometimes called “Malta fever” or “undulant fever” because of its relapsing fever pattern.

📖 About

• Intracellular Gram-negative coccobacilli (only 4 species pathogenic to humans).
• Zoonosis – transmitted from animals to humans. Human-to-human spread is extremely rare.
• Endemic in Mediterranean, Middle East, Africa, Asia, and Latin America.

🔬 Microbiology

• B. melitensis 🐐 (goats, sheep, camels) → most severe disease.
• B. abortus 🐄 (cattle) → usually milder disease.
• B. suis 🐖 (pigs) → associated with suppurative complications.
• B. canis 🐕 (dogs) → less common, milder illness.

🩺 Clinical Features

• Incubation period: 1–4 weeks.
• Transmission: Infected milk, cheese, yoghurt, butter, uncooked meat, or inhalation in abattoir/lab workers.
• Systemic symptoms: Pyrexia, rigors, drenching sweats 😰, lethargy, headache.
• Musculoskeletal: Arthralgia, myalgia, suppurative arthritis, synovitis, bursitis, spondylitis, osteomyelitis, paravertebral/psoas abscess.
• CNS: Meningitis, stroke, cranial nerve palsy, myelopathy, subarachnoid haemorrhage, radiculopathy.
• Ocular: Uveitis, retinal thrombophlebitis 👁️.
• Cardiac: Myocarditis, endocarditis ❤️ (leading cause of mortality).
• Respiratory: Pneumonitis, lung abscess, hilar adenopathy.
• Abdominal: Splenic abscess/calcification, hepatitis, orchitis, epididymo-orchitis.
• Characteristic pattern: Undulant fever 🌡️ (recurrent fever with sweats, improving then relapsing).

🧪 Investigations

• Blood cultures: Require prolonged incubation (Brucella grows slowly). B. melitensis is the most readily cultured.
• CSF culture: if neurological involvement suspected.
• Serology: Standard agglutination test – diagnostic titre >1:320 or a four-fold rise in titre.
• FBC, LFTs: may show anaemia, leukopenia, raised transaminases.

💊 Management

• Adults (first-line): Doxycycline 100 mg BD for 6 weeks + IV Gentamicin for 7 days (or Streptomycin IM for 2–3 weeks).
• Bone involvement: Add Rifampicin 600–900 mg OD for 6 weeks.
• Neurobrucellosis: Add Ceftriaxone 2 g IV BD for 4–6 weeks.
• Children: Co-trimoxazole (Trimethoprim/Sulfamethoxazole) + aminoglycoside (Gentamicin or Streptomycin) or Rifampicin.
• Endocarditis: Requires triple therapy (Doxycycline + Rifampicin + Aminoglycoside) and often surgical valve replacement.

⚠️ Key Points

• Relapse is common if treatment is too short ⏳.
• Brucellosis is a notifiable disease in many countries.
• Prevention: pasteurisation of milk, protective measures for abattoir/laboratory workers, vaccination of livestock.

📚 References

• WHO Fact Sheet on Brucellosis
• BNF Guidance