Clinical presentation and intoxication syndrome
The disease manifests extremely acutely: with shaking chills and a rapid temperature rise to 39–40 °C. Systemic inflammatory response syndrome progresses rapidly, leading to the development of encephalopathy and hemodynamic disorders.
Specific systemic signs:
- Appearance: Facies pestica develops — a bright, puffy face with hyperemia of the sclera and conjunctiva, expressing suffering.
- Oropharynx: Mucous membranes are dry, the tongue is heavily coated with a characteristic white plaque ("chalky tongue").
- Neurological status: Patients are disoriented, restless, speech is disjointed. A unsteady gait, delirious states, sopor, or pronounced motor agitation are possible.
- Hemodynamics and hemostasis: Tachycardia develops (up to 140 bpm), muffled heart sounds, arterial hypotension (ITS). Positive capillary fragility test (tourniquet test), single hemorrhages or areas of necrosis appear.
Assessment of local status
The bubonic form of plague is characterized by specific lymph node involvement (most commonly inguinal or axillary), which is accompanied by a forced limb posture (abduction).
Characteristics of the plague bubo:
- Rate of development: Forms extremely rapidly (within the first days of the disease).
- Structure: Massive, dense, relatively immobile infiltrate, sharply painful upon palpation (the patient reacts with a groan or grimace).
- Periadenitis: The contours of the infiltrate have no clear boundaries, the nodes are fused together and with the skin.
- Skin: The skin over the infiltrate is tense, brightly hyperemic, acquiring a purplish-red color in the center.
- Destruction: Inflammation is of a hemorrhagic-necrotic nature; fluctuation and rupturing bullae may appear.
In the case of development of the secondary pulmonary form, on days 5–6 of the disease, dyspnea appears (tachypnea up to 40/min), coughing with frothy sputum tinged with bright red blood. A discrepancy between pronounced respiratory failure and initially scant auscultatory findings is characteristic (later, multiple rales and foci of dullness appear).
Laboratory and specific diagnostics
A patient with suspected plague is subject to urgent hospitalization in a box unit (with the primary diagnosis of "Fever of unknown origin", if the timing aligns with the incubation period). Sample collection is performed before the initiation of antibacterial therapy.
- Specific diagnostics: Sputum, blood, throat swab, and punctate from the peripheral part of the bubo are examined. Microscopy is performed (methylene blue staining reveals bipolar-staining bacilli), along with bacteriological culture and biological testing on guinea pigs.
- Hemogram (CBC): Pronounced leukocytosis (e.g., up to 28,000), marked band neutrophil shift to the left (up to 37%), appearance of young forms, myelocytes, and Türk cells, as well as toxic granulation of neutrophils.
- Severity assessment (objectification): It is mandatory to perform a biochemical blood analysis, blood gas analysis (acid-base balance), coagulography to assess hemostasis, and chest radiography.
Differential diagnosis with tularemia
Plague is primarily differentiated from tularemia. Despite the similarity of transmission routes (natural foci), the clinical picture has a number of fundamental differences.
| Sign | Plague | Tularemia |
|---|---|---|
| Intoxication | Severe, rapidly leads to ITS and DIC syndrome | Moderate, runs a benign course |
| Bubo | Early maturation, pronounced destructive periadenitis, sharp pain | Matures later; destructive periadenitis is not characteristic |
| Hemogram (peak period) | Pronounced leukocytosis, left shift | Leukopenia, lympho-monocytic reaction |
| Generalization | Frequent (secondary pneumonia) | Secondary generalized forms are extremely rare |
Briefly: answers to topical questions
What specific laboratory diagnostic methods are used to confirm plague?
The following specific laboratory diagnostic methods are used to confirm the disease:
- Bacterioscopic method — detection of ovoid, bipolar-stained microbial cells.
- Fluorescent-serological method — detection of pathogen fluorescence via luminescence microscopy.
- Bacteriological method — isolation of a pure culture of Yersinia pestis by inoculation onto solid nutrient media.
- Biological assay — testing on laboratory animals.
- Serological methods — detection of antibodies to the pathogen capsular antigen (IHA and ELISA).
- Immunological methods — detection of the FI antigen.
- Molecular biological methods — hybridization method and polymerase chain reaction (PCR).
What is the duration of the incubation period in plague infection?
On average, the incubation period for plague infection ranges from 3 to 6 days. According to international quarantine regulations, the period of isolation and observation for close contacts is strictly regulated and lasts 6 days. As an exception, the incubation period can be significantly shortened to several hours or, conversely, prolonged to 8–10 days. Additionally, prior vaccination-induced immunity in a patient can cause an atypical prolongation of the incubation period.
Which antibacterial drugs are the drugs of choice for etiotropic treatment of plague?
The referenced guidelines indicate the following etiotropic antibacterial therapy for plague:
- Streptomycin 1.0 g intramuscularly twice a day.
- Subsequently — combination of streptomycin with doxycycline.
Antibacterial therapy is initiated immediately after specimen collection for bacteriological examination.
Plague: "Three M's" — Fulminant onset, Chalky tongue, Massive (painful) bubo.
Class and exam questions
When is surgical treatment of a plague bubo indicated?
Surgical incision of the bubo is performed strictly by indication — only when obvious signs of fluctuation appear.
What is the characteristic auscultatory finding in secondary plague pneumonia?
At the onset of pneumonia, there is a discrepancy between the severity of the condition (dyspnea, hemoptysis) and the scarcity of physical findings in the lungs; the full clinical picture with rales and dullness appears later.
What else to study on this topic
- Principles of antibacterial therapy for plague (regimens with streptomycin and doxycycline)
- Pathogenesis of infectious-toxic shock in plague
- Anti-epidemic measures and regulations for managing patients with particularly dangerous infections (PDIs)
- Criteria for discharging convalescents after plague
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