Plague

Plague is a severe infectious disease mainly transmitted by rat fleas, a natural focal disease widespread among wild rodents. Clinically it presents as fever, severe toxemia, lymphadenopathy, pneumonia, and bleeding tendency. It has caused multiple historical pandemics with tens of millions of deaths; China also had epidemics before liberation with extremely high fatality.

Common Symptoms

Coma; diarrhea; dyspnea; Yi Yupin; irritability; abdominal pain; fatigue; low fever; cyanosis; nausea; toxemia

Causes and Pathogenesis

Transmission: Rat flea bites are the main route (rodent→flea→human for bubonic plague); the oriental rat flea Xenopsylla cheopis is the main vector. Respiratory droplet transmission from pneumonic patients causes human-to-human spread and large epidemics. Skin transmission occurs through handling infected rodent pelts/meat or contact with patient blood/pus. Ingestion of undercooked infected meat also infects. Pathogenesis: After skin entry, bacilli reach regional nodes causing primary lymphadenitis with marked congestion, hemorrhage, and coalescence; nodes contain abundant bacilli and toxins that enter the blood causing systemic infection, septicemia, and severe toxemia; if progression stops, it is bubonic plague; hematogenous spread to lungs causes secondary pneumonic plague, which then spreads via droplets causing primary pneumonic plague; all forms may cause secondary septicemia; fulminant cases may have minimal skin/node/lung lesions yet rapidly become primary septicemic plague. Basic lesions are vascular/lymphatic endothelial damage and acute hemorrhagic necrosis; nodes show coagulative necrosis; lungs show bronchopneumonia or lobar pneumonia with bloody frothy exudate; widespread petechiae and serosanguineous effusions.

Treatment

Drug therapy, supportive therapy

Preventive Measures

1. Manage sources: strengthen international quarantine; isolate suspected/confirmed cases and report to health authorities within 6 h; quarantine contacts for 6 days; isolate pneumonic plague until 6 negative sputum cultures, bubonic until nodes fully resolve plus 7 days; disinfect or burn patient excreta/utensils; lock down endemic areas for at least 9 days; conduct rat-catching and flea-killing campaigns. 2. Thoroughly kill fleas. 3. Protect susceptibles: (1) Personal protection: protective clothing, masks, goggles, gloves, boots; contacts may receive sulfadiazine/tetracycline 2 g/day in 4 doses or streptomycin 1 g/day in 2 IM doses for 6 days (though some find bacilli insensitive to sulfonamides). (2) Vaccination: Current live/ killed/purified vaccines are imperfect; China uses avirulent live vaccine by scarification or subcutaneous injection (adults 1 ml); immunity starts at 10 days, peaks at 1 month, declines after 6 months, vanishes after 1 year; boosters every 6-12 months. Recombinant F1/V subunit vaccines show promise. Strictly handle Y. pestis as a dangerous pathogen; prevent aerosol/flea-borne infection; disinfect cultures and equipment. Avoid contact with sick animals/carcasses; use flea repellents; reduce rodent habitats; control insects before rodenticide use.

Department to Visit

It is recommended to visit the Infectious Diseases department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.