Generalized and rare forms
In addition to typical lymph node involvement, the infection can take extremely severe generalized clinical courses.
- Primary septic form: Develops fulminantly (within 1–3 days) without primary changes at the site of bacterial entry. Characterized by profound CNS depression (status typhosus), rapid development of infectious-toxic shock (ITS) and DIC syndrome. Massive skin hemorrhages and bleeding gave rise to the historical name of the disease — the "Black Death".
- Secondary pneumonic plague: Arises against the background of other forms. Accompanied by a sharp increase in intoxication, chest pain, and cough (sputum changes from mucous to bloody). Physical findings are meager due to the small-focal nature of the pneumonia. The patient becomes a source of infection for the primary pneumonic form.
- Rare variants: Meningeal form (development of serous-hemorrhagic and then purulent meningoencephalitis), intestinal form ("plague cholera" with bloody diarrhea), and fulminant form (death occurs within a few hours).
Severity criteria and prognosis
The main measure of severity for any form of the disease is the severity of intoxication syndrome. The physician evaluates:
- Fever level and frequency of chills.
- Hemodynamic and respiratory parameters.
- Renal function (urinary output).
- Hemostatic system status and neuropsychiatric status.
An unconditional sign of a severe course is the development of ITS of any degree. The prognosis directly depends on the speed of diagnosis. If antibacterial therapy is not prescribed, mortality approaches 100%. Treatment initiated on the first day virtually guarantees saving a life, whereas delaying the start of therapy to 2–3 days reduces survival to 50%.
Infection complications
Complications are divided into specific (caused by pathogenesis) and nonspecific.
Specific complications include:
- Secondary generalization. Prognostically extremely unfavorable are primary buboes in the neck (high risk of breakthrough into the CNS) and axillary region (risk of dissemination to the lungs).
- Formation of secondary buboes (small, multiple, mildly painful, without periadenitis).
- Development of shock, acute renal failure, cerebral edema, and DIC syndrome.
Nonspecific complications arise due to secondary flora (nonspecific pneumonia, erysipelas, adenophlegmon, gangrene) or against the background of decompensation of chronic diseases. With a prolonged course without treatment, pronounced cachexia may develop.
Laboratory verification
Diagnosis requires strict biological safety measures.
- Complete blood count: Neutrophilic leukocytosis. In extremely severe cases — leukopenia, profound left shift to promyelocytes, toxic granularity of neutrophils, normoblasts, and the presence of bacteria in the smear.
- Bacteriological method: Gold standard. Hottinger agar, Martin media, and blood agar are used. Primarily sterile media (CSF, blood) are inoculated into broths. The result is evaluated after 48–72 hours.
- Biological assay: Infection of guinea pigs or white mice (death on days 5–9). To accelerate death, animals may be administered hydrocortisone.
- Rapid methods: Bacterioscopy (staining of bipolar rods with methylene blue) provides an answer in 2 hours. PCR allows detection of single pathogen DNA within a few hours.
- Immunology and serology: Detection of the capsular antigen F1 (ELISA, IHA) and antibodies (for retrospective analysis).
Epidemiological history and differential diagnosis
It is extremely important to record the exact time of the first chill. The physician must ascertain the fact of being in an endemic focus, contacts with rodents, fleas, febrile patients (especially those with a cough), animal mortality, and occupational risks.
In the initial period, plague is differentiated with two groups of diseases:
- By appearance and acute onset: typhus, leptospirosis, influenza, hemorrhagic fevers, pseudotuberculosis (similar infectious-toxic syndrome with facial hyperemia and scleritis).
- By hyperacute septic course: meningococcal sepsis, tropical malaria, severe forms of anthrax and tularemia, erysipelas.
Briefly: answers to topical questions
What is the duration of the incubation period in bubonic plague?
The incubation period for plague averages 3 to 6 days.
- Standard period — 3–6 days.
- Quarantine period — 6 days (determines the period of isolation and observation of contacts).
- Exceptions — the incubation time can be shortened to a few hours or prolonged to 8–10 days.
What antibacterial drugs are used for etiotropic treatment of bubonic plague?
For etiotropic therapy of plague, the antibiotics streptomycin and doxycycline are used.
- Streptomycin — administered intramuscularly at a dose of 1.0 g twice a day.
- Doxycycline — used at subsequent stages of treatment in combination with streptomycin.
The use of antibacterial drugs begins immediately after collecting biomaterial for study due to the severity of the patient's condition.
How to remember the dangerous localization of buboes: "Neck — Shock for the brain (meningitis), Armpits — Pneumonia (generalization to the lungs)".
Class and exam questions
With this form, there are no visible pathological changes in the area of the portal of entry, and the disease starts immediately with severe shock and encephalopathy.
With this form, there are no visible pathological changes in the area of the portal of entry, and the disease starts immediately with severe shock and encephalopathy.
What is the epidemiological danger of secondary pneumonic plague?
A patient with this form begins to excrete bacteria with sputum, becoming a highly contagious source of airborne droplet infection for others (they will develop primary pneumonic plague).
Can liquid media be used for culturing sputum or feces when plague is suspected?
No. Yersinia pestis has poor competitiveness in broths, so liquid media are used only for primarily sterile biomaterials (blood, CSF) collected under aseptic conditions.
What else to study on this topic
- Pathogenesis of infectious-toxic shock and DIC syndrome in plague.
- Structural features of the F1 antigen and its role in immunological diagnosis.
- Pathomorphological picture of animal organs during a biological assay.
- Differential diagnosis of buboes in plague and tularemia.
- Mechanisms of secondary generalization in skin and bubonic forms.
Master the complete topic in the «Infectious Diseases» course
This is a summary. The course covers everything tested in classes and exams.
- Full study guide on "Bubonic plague" and another 3,312 pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 41 video lessons on the subject
Other topics in the section "Zoonotic infections — 2024 study guide"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.