Plague
Plague is an acute and exceptionally dangerous infectious disease (classified in Vietnam as a Group A communicable disease) caused by Yersinia pestis, a facultatively anaerobic gram-negative bacillus. It spreads mainly through the bite of the rat flea (Xenopsylla cheopis) or through direct contact with the tissues or body fluids of infected rodents. Highly virulent, Y. pestis invades the lymphatic system and causes acutely swollen, painful lymph nodes (bubonic plague). It can progress to bloodstream infection (septicemic plague) and widespread small-vessel blockage, leading to symmetrical purpura and dry gangrene of the fingers and toes, which is why the disease was historically called the "Black Death."
At Haute-Derma, managing suspected plague or its effects on the skin requires urgent isolation and diagnosis, powerful bactericidal antibiotics, surgical debridement of dead tissue, and scar reconstruction once the acute phase has passed.
Pathogenesis and Bacterial Virulence
Sources of Infection and Routes of Entry
- The reservoir-vector-host cycle: Yersinia pestis persists in nature among rodents such as rats, squirrels and prairie dogs. The flea Xenopsylla cheopis feeds on an infected host, and the bacteria multiply until they block the flea's proventriculus. The flea stays constantly hungry, bites again and again, and regurgitates bacteria into the skin of each new host.
- Entry through the skin: Bacteria enter through a flea bite or through scratches and abrasions that come into direct contact with the blood or tissue of an infected animal.
Virulence Factors and Damage to the Microcirculation
- Surface proteins and immune-evasion antigens: The type III secretion system (T3SS) injects virulence proteins called Yops (Yersinia outer proteins) directly into macrophages and neutrophils, disabling phagocytosis and wrecking the cell's cytoskeleton. The F1 capsular antigen protects the bacterium from killing by complement.
- Necrosis and disseminated intravascular coagulation (DIC): Exotoxins and lipopolysaccharide (LPS) switch on the clotting cascade throughout the body and damage the vascular endothelium. Countless tiny clots block the vessels supplying the skin, producing hemorrhagic, necrotic purpura and dry gangrene of the fingers, toes and tip of the nose.
Clinical Forms of Plague Affecting the Skin
Bubonic Plague (The Most Common Form)
- Incubation period: 2–6 days after the flea bite.
- The bubo: Illness begins abruptly with high fever (39–40°C), shaking chills and a severe headache. The draining lymph nodes (most often in the groin, 60%; armpit, 20%; neck, 10%) swell very quickly to 2–10 cm. They are extremely painful and stuck fast to the surrounding tissue, so the patient cannot move the limb. The node may soften with pus or burst, releasing foul-smelling discharge.
Cutaneous Plague
- Blisters and pustules on a dusky red base appear at the site of the flea bite.
- These quickly break down into a necrotic ulcer with a gray-black base and a firm, raised edge, surrounded by spreading swelling and bruising.
Septicemic Plague and Gangrene of the Extremities
- Purpura fulminans: Deep purple patches of bleeding appear in the skin and rapidly turn black as the tissue dies and dries out.
- Dry gangrene of the extremities: Severe loss of blood supply from small-vessel blockage turns the fingers and toes, and sometimes an entire hand or foot, black, and they may drop off if not treated in time.
Assessment and Diagnosis at Haute-Derma
Exposure History and Isolation Alert
- We ask about travel to areas where plague is endemic and about contact with rats, fleas or rodent bites within the past 10 days.
- If plague is suspected, we immediately start high-level respiratory and contact isolation and notify the public health authorities, as required for Group A diseases.
Urgent Microbiological Diagnosis
- Samples are taken by fine-needle aspiration (FNA) of the bubo, from blister fluid, or from blood.
- Gram, Giemsa or Wright stain: Shows gram-negative coccobacilli with dark staining at both ends, the characteristic "safety-pin" appearance.
- Confirmatory tests: Rapid F1 antigen test, culture under biosafety level 3 (BSL-3) conditions, or PCR to detect Yersinia pestis genes.
Medical Treatment and Recovery Care at Haute-Derma
Standard Antibiotic Regimens (Started as Soon as Plague Is Suspected)
- First-line antibiotics:
- Aminoglycosides: streptomycin 1 g intramuscularly twice daily (or gentamicin 5 mg/kg intravenously once daily) for 10–14 days.
- Alternatives (oral, mild cases or prophylaxis):
- Doxycycline 100 mg by mouth twice daily for 10–14 days.
- Ciprofloxacin 400 mg intravenously every 12 hours (or 500 mg by mouth twice daily).
- Prophylaxis for close contacts: doxycycline 100 mg twice daily or ciprofloxacin 500 mg twice daily for 7 days.
Aesthetic Skin Restoration After the Acute Phase
- Surgery: Working with surgeons, we debride areas of dry gangrene once the bloodstream infection and bacteria are fully under control.
- Tissue regeneration and scar improvement:
- Topical products containing epidermal growth factor (EGF), panthenol (vitamin B5) and madecassoside are applied to encourage granulation tissue in the ulcer bed.
- Once the skin has fully closed, short-pulse fractional laser (fractional CO2 or Er:YAG) combined with topical niacinamide is used to flatten scars, release tight scar bands and even out skin color in the affected area.
