Plague

Plague is a zoonotic infection caused by Yersinia pestis, transmitted by flea bites from rodents and via respiratory droplets in pneumonic disease.

• Endemic foci: Madagascar (most cases), Democratic Republic of Congo (Ituri), Peru, Uganda, and the western United States.
• Forms: bubonic (most common; 30 to 60% untreated mortality), septicaemic, and pneumonic (nearly 100% fatal untreated, and spread person to person).
• Incubation 2 to 8 days (bubonic) and 1 to 3 days (pneumonic).
• Public health emergency requiring immediate reporting.

• Bubonic: sudden fever, chills, headache, and extremely tender, swollen lymph node (bubo) in the groin, axilla, or neck.
• Septicaemic: fever, shock, DIC, purpura, gangrene of digits (black death), and abdominal pain.
• Pneumonic: fever, cough, dyspnoea, haemoptysis, and rapid respiratory failure.
• Meningitis is a rare complication.

• Culture of bubo aspirate, blood, sputum, or CSF (laboratory biosafety required), Gram or Wayson stain showing bipolar "safety pin" Gram negative coccobacilli.
• Rapid diagnostic test for F1 antigen, PCR, and paired serology.
• Chest X-ray for pneumonia.
• Exclude tularaemia, anthrax, cat scratch disease, lymphogranuloma venereum, staphylococcal lymphadenitis, melioidosis, and other septicaemic illnesses.

• Treat immediately, without waiting for confirmation.
• First line: streptomycin 1 g IM twice daily (or 15 mg/kg every 12 hours) for 10 days; gentamicin 5 mg/kg IV or IM daily (or 2 mg/kg loading then 1.7 mg/kg every 8 hours) for 10 days.
• Alternatives: doxycycline 100 mg twice daily (or 200 mg loading), ciprofloxacin 500 to 750 mg orally twice daily (400 mg IV every 8 to 12 hours), levofloxacin 750 mg daily, chloramphenicol 25 mg/kg IV every 6 hours for meningitis.
• Isolation: droplet precautions for pneumonic plague for at least 48 hours of effective therapy; strict flea control before treatment.
• Post-exposure prophylaxis for close contacts: doxycycline 100 mg twice daily or ciprofloxacin 500 mg twice daily for 7 days.
• Supportive: fluids, vasopressors, ventilation, and management of DIC.
• Control rodent and flea populations (insecticide before rodenticide); a vaccine is not widely available.