Clinical presentation and laboratory diagnostics
The disease starts rapidly. The main clinical phenomenon is clinical-radiological dissociation: the radiogram shows only isolated small pneumonic foci, yet these findings do not correlate at all with the severe dyspnea and profound intoxication. Central nervous and cardiovascular system dysfunction develops before a physician can detect signs of pneumonia by percussion or auscultation.
On physical examination, characteristic «spots of death» may appear on the skin. In the absence of emergency care, the patient dies within two to three days.
Laboratory blood analysis (hemogram) reveals marked neutrophilic leukocytosis with a left shift. Microscopy of a blood smear and thick drop is mandatory to exclude malaria and confirm the bacterial nature of the infection. A rare but specific sign of plague is the presence of bipolar-stained microorganisms in the blood.
Differential diagnosis: anthrax and tularemia
At the height of the disease, the pneumonic form of plague must be differentiated from other zoonotic infections affecting the respiratory system.
- Pneumonic anthrax: Has virtually no reliable clinical differences from plague. Primary pneumonia in anthrax is extremely rare; it is more often the result of generalization of the cutaneous form of infection. Possible reference points are initial catarrhal symptoms and more pronounced objective signs of lung involvement. An early symptom of anthrax sepsis is a change in the mediastinal shadow and tracheal displacement due to mediastinitis and exudative pleurisy.
- Pneumonic tularemia: Differs by less pronounced intoxication, which never reaches «plague» severity. Fever is of an irregular type and accompanied by sweating. Cough is dry, later followed by scanty mucopurulent sputum. The physical picture is poor. Radiography is of decisive importance: enlarged intrathoracic lymph nodes and hilar pneumonia are detected no earlier than the 7th day. Confirmation of the diagnosis requires allergological and serological tests.
Differences from common pneumonia and other syndromes
Plague often has to be distinguished from severe polysegmental pleuropneumonia (lobar pneumonia). In common pneumonia, there is a clear correlation between the severity of the patient's condition and the area of lung lesion. Signs of lobar inflammation increase sequentially from the first day. Symptoms from the central nervous system and heart develop gradually. Sputum is initially viscous and difficult to expectorate, then becomes «rusty». Hemoptysis is less abundant than in plague and is often accompanied by herpetic eruptions.
If plague proceeds with the rapid development of sepsis or shock, the differential series includes meningococcemia, anthrax sepsis, and staphylococcal toxic shock syndrome. With the development of acute respiratory distress syndrome (ARDS), severe influenza, SARS, and hantavirus cardiopulmonary syndrome must be excluded. In these cases, the decisive factor is epidemiological history (seasonality, age, travel to endemic countries in Asia or the USA).
Principles of isolation and treatment
All patients with suspected plague are subject to immediate mandatory hospitalization in a strictly individual box. The main component of treatment is emergency etiotropic antibacterial therapy with drugs of proven efficacy, as well as pathogenetic and symptomatic support.
Transfer of the patient from the box to a general ward (for a specific clinical form) is permitted only if three conditions are met:
- Exclusion of specific pneumonia.
- Triple negative result of sputum bacteriological culture for Yersinia pestis.
- Clinical efficacy of antibiotics lasting for at least 48 hours.
The regimen is prescribed strictly individually, taking into account the state of the central nervous system and hemodynamics (strict bed rest in the first days). Diet therapy ranges from tube enteral nutrition in an extremely critical condition to standard therapeutic tables (№15, 13) or specialized ones (№1, 2, 4, 5, 7) in case of liver, kidney, or gastrointestinal tract damage.
Briefly: answers to topical questions
Which specific antibacterial drugs are used for etiotropic therapy of pneumonic plague?
For etiotropic antibacterial therapy, sources indicate: streptomycin 1.0 g intramuscularly 2 times a day; subsequently, a combination of streptomycin with doxycycline. Antibacterial therapy is started immediately after taking material for bacteriological examination. It is also indicated that the pathogen is sensitive to streptomycin, tetracycline, rifampicin, and chloramphenicol, but resistant to penicillin.
What is the duration of the incubation period for primary pneumonic plague?
Sources do not specify a separate incubation period duration specifically for the primary pneumonic form. For plague in general, the incubation period averages 3–6 days; according to international quarantine rules, the isolation and observation period for contacts is 6 days. In exceptional cases, it can be shortened to a few hours or extended to 8–10 days. In the presented clinical review of the primary pneumonic form in a vaccinated patient, vaccine-induced immunity explained the atypical prolongation of the incubation period and the presence of a prodromal period: chills and malaise were noted for a day while activity was maintained.
Plague dissociation: dots on the scan, shock and dyspnea in the clinic.
Class and exam questions
What is clinical-radiological dissociation in pneumonic plague?
Scanty radiological findings (small foci) do not correspond to the extremely severe degree of dyspnea and profound systemic intoxication of the patient.
How does pneumonic plague objectively differ from lobar pneumonia?
In lobar pneumonia, the severity of the condition strictly corresponds to the volume of lung damage, intoxication increases gradually, and sputum acquires a «rusty» color. In plague, hemoptysis is more abundant, and shock develops fulminantly.
What criteria allow the transfer of a plague patient out of an individual box?
It is necessary to clinically exclude specific pneumonia, obtain a negative sputum bacterial culture for the pathogen, and confirm a sustained effect of antibiotic therapy for at least 48 hours.
What is the main cause of death in the pneumonic form?
Patients who do not receive timely etiotropic treatment usually die on days 2–3 from massive hemorrhagic pulmonary edema.
What else to study on this topic
- Differential diagnosis of bubonic plague (tularemia, cat scratch disease)
- Differences between the cutaneous form of plague and anthrax
- Management tactics for patients with septic plague
- Specific antibacterial therapy and drug selection
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