Plague

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    A zoonosis caused by the Gram-negative bacillus Yersinia pestis that mainly affects wild and domestic rodents.

    Plague is transmitted to man by the bite of an infected flea vector or through a break in the skin by contact with a rodent. Human-to-human transmission occurs through the bites of human fleas, or, in the case of pneumonic plague, by inhaling infected droplets expelled by coughing.

    Vast foci of infection remain in Asia, Africa, Madagascar, and in North and South America a Citation a. For more information on distribution of natural foci:
    http://www.who.int/csr/disease/plague/Plague-map-2016.pdf
    .

    Clinical features and progress

    There are 3 main clinical forms:

    • Bubonic plague is the most common form: high fever, chills, headache, associated with one (or more) very painful lymph node, usually inguinal (bubo). Frequent gastrointestinal signs: abdominal pain, vomiting, diarrhoea, etc. The mortality rate in untreated patients is approximately 50% as a result of septicaemia.
    • Septicaemic plague is a complication of untreated bubonic plague and is a fulminant illness.
    • Pneumonic plague is a very contagious form: high fever, chills, headache, myalgia associated with paroxysmal coughing, blood stained sputum and respiratory distress. This form progresses rapidly, and is fatal unless treated. It occurs either as a complication of bubonic plague or as the result of a primary infection.

     

    Occasionally, the disease can take the form of meningitic plague.

    Laboratory

    • Isolation of Y. pestis (direct examination and culture) from lymph node aspirate, blood, sputum, cerebrospinal fluid, depending on the form involved.
    • Serodiagnosis: ELISA reads positive soon after the onset of the illness.
    • Transportation of the samples requires a cold chain (failing that, the temperature must be kept below 30 °C).

    Management and treatment

    • When plague is suspected: take samples for cultures and antibiotic sensitivity testing and then treat immediately without waiting for the diagnosis to be confirmed. Inform the health authorities as soon as the diagnosis has been confirmed.
    • Isolation:
      • Patients suffering from bubonic plague do not have to be isolated. Treat the patient and his/her bedding and clothing with an insecticide (e.g. permethrin 0.5% powder; see Pediculosis, Chapter 4). Observe standard precautions (handwashing, gowns, gloves, etc.).
      • Patients with primary or secondary pneumonic plague must be strictly isolated. Their bedding, clothing, sputum and excreta must be disinfected with a chlorinated solution. Observe standard precautions (handwashing, gowns, gloves, etc.) and both the patient and carers should wear facemasks for 48 hours after beginning appropriate antibiotherapy .

    Treatment of suspected or confirmed cases

    If treatment is begun early, recovery is rapid and complete. Penicillins, cephalosporins and macrolides should not be used.

    Aminoglycosides, tetracyclines, chloramphenicol and sulphonamides are effective. Follow national recommendations. For information:

     

    streptomycin IM for 10 days
    Children: 15 mg/kg every 12 hours (max. 2 g daily)
    Adults: 1 g every 12 hours

     

    gentamicin IM or IV for 10 days
    Children: 2.5 mg/kg every 8 hours
    Adults: 5 mg/kg once daily

     

    doxycycline PO for 10 days
    Children 8 years and over: 2 mg/kg 2 times daily (max. 200 mg daily)
    Adults: 100 mg 2 times daily or 200 mg once daily

     

    chloramphenicol PO or IV for 10 days
    Children 1 year to 12 years: 25 mg/kg every 8 hours
    Children 13 years and over and adults: 1 g every 8 hours

     

    Indications

    First choice

    Alternative

    Bubonic plague

    doxycycline

    chloramphenicol or streptomycin

    Pneumonic plague

    streptomycin

    Septicaemic plague

    streptomycin

    chloramphenicol

    Meningitic plague

    chloramphenicol

    Pregnant or breast-feeding women

    gentamicin

     

    Chemoprophylaxis of contacts

    In the event of contact with a pneumonic plague patient or direct contact with infected body fluids or tissues and within one week after the end of exposure:
    doxycycline PO for 7 days
    Children 8 years and over: 2 mg/kg 2 times daily (max. 200 mg daily)
    Adults: 100 mg 2 times daily or 200 mg once daily
    or
    ciprofloxacin PO for 7 days
    Children: 20 mg/kg 2 times daily (max. 1 g daily)
    Adults: 500 mg 2 times daily 

    Prevention

    • Flea vector control is essential to controlling an epidemic.
    • Long-term prevention: environmental sanitation and control of rodent reservoir.
    • Vaccination against plague is indicated for laboratory technicians handling rodents or working with Y. pestis and is not as a method for controlling an epidemic.

     

    Footnotes