Diagnosis of plague

Plague diagnostics is based on clinical and epidemiological data: severe intoxication, the presence of ulcers, bubo, severe pneumonia, hemorrhagic septicemia in individuals in the natural focal zone of plague, living in places where epizootics (mortality) among rodents have been observed or there is an indication of registered cases of the disease. Each suspected patient should be examined.

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Indications for consultation with other specialists

Consultations are usually conducted to clarify the diagnosis. If the bubonic form is suspected, a surgeon's consultation is indicated; if the pulmonary form is suspected, a pulmonologist's consultation is indicated.

Specific and non-specific laboratory diagnostics of plague

The blood picture is characterized by significant leukocytosis, neutrophilia with a shift to the left and an increase in ESR. Protein is found in the urine. During an X-ray examination of the chest organs, in addition to an increase in the mediastinal lymph nodes, focal, lobular, less often pseudolobar pneumonia can be seen, and in severe cases - RDS. In the presence of meningeal signs (rigidity of the occipital muscles, a positive Kernig's sign), a lumbar puncture is necessary. In the cerebrospinal fluid, three-digit neutrophilic pleocytosis, a moderate increase in protein content and a decrease in glucose levels are most often detected. Specific diagnostics of plague is based on the study of bubo punctate, ulcer discharge, carbuncle, sputum, nasopharyngeal smear, blood, urine, feces, cerebrospinal fluid, autopsy material. The rules for collecting material and its transportation are strictly regulated by the "International Health Rules". The material is collected using special dishes, bixes, and disinfectants. The personnel work in anti-plague suits. A preliminary conclusion is given based on microscopy of smears stained according to Gram, methylene blue, or treated with a specific luminescent serum. Detection of ovoid bipolar rods with intense staining at the poles (bipolar staining) allows one to assume a diagnosis of plague within an hour. For final confirmation of the diagnosis, isolation, and identification of the culture, the material is sown on agar in a Petri dish or on broth. After 12-14 hours, characteristic growth appears in the form of broken glass ("lace") on agar or "stalactites" in broth. Final identification of the culture is made on the 3rd-5th day.

The diagnosis can be confirmed by serological studies of paired sera in RPGA, but this method has a secondary diagnostic value. Pathological changes in mice and guinea pigs infected intraperitoneally are studied after 3-7 days, with the sowing of biological material. Similar methods of laboratory isolation and identification of the pathogen are used to detect plague epizootics in nature. Materials from rodents and their corpses, as well as fleas, are taken for the study.

Example of diagnosis formulation

A20.0. Plague, bubonic form. Complication: meningitis. Severe course.

All patients with suspected plague are subject to emergency hospitalization by special transport to an infectious diseases hospital, in a separate box with all anti-epidemic measures observed. Personnel caring for plague patients must wear a protective anti-plague suit. Household items in the ward, the patient's excrement are subject to disinfection.

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Differential diagnosis of plague

The list of nosologies with which it is necessary to conduct differential diagnostics depends on the clinical form of the disease. Differential diagnostics of cutaneous plague should be carried out with cutaneous anthrax, bubonic plague - from cutaneous tularemia, acute purulent lymphadenitis, sodoku. benign lymphoreticulosis, venereal granuloma; pulmonary form - from lobar pneumonia, pulmonary anthrax. Septic form of plague should be distinguished from meningococcemia and other hemorrhagic septicemia. Diagnosis of the first cases of the disease is especially difficult. Epidemiological data are of great importance: stay in foci of infection, contact with rodents sick with pneumonia. It should be borne in mind that early use of antibiotics modifies the course of the disease. Even the pulmonary form of plague in these cases can proceed benignly, but patients still remain infectious. Given these features, in the presence of epidemiological data in all cases of diseases occurring with high fever, intoxication, lesions of the skin, lymph nodes and lungs, plague should be excluded. In such situations, it is necessary to conduct laboratory tests and involve specialists from the anti-plague service.

Differential diagnosis of plague

Nosological form	General symptoms	Differential criteria
Anthrax, cutaneous form	Fever, intoxication, carbuncle, lymphadenitis	Unlike the plague, fever and intoxication appear on the 2nd-3rd day of the disease, the carbuncle and the area of swelling around it are painless, there is an eccentric growth of the ulcer
Tularemia, bubonic form	Fever intoxication, bubo. hepatosplenic syndrome	Unlike plague, fever and intoxication are moderate, the bubo is slightly painful, mobile, with clear contours; suppuration is possible in the 3rd-4th week and later, after the temperature has normalized with a satisfactory condition of the patient, there may be secondary buboes
Purulent lymphadenitis	Polyadenitis with local pain, fever, intoxication and suppuration	Unlike plague, there is always a local purulent focus (panaritium, suppurating abrasion, wound, thrombophlebitis). The appearance of local symptoms is preceded by fever, usually moderate. Intoxication is weakly expressed. Periadenitis is absent. The skin over the lymph node is bright red. Its increase is moderate. Hepatosplenic syndrome is absent.
Lobar pneumonia	Acute onset, fever, intoxication. possible separation of sputum with blood Physical signs of pneumonia	Unlike plague, intoxication increases by the 3rd-5th day of illness. Encephalopathy is not typical. Physical signs of pneumonia are clearly expressed, sputum is scanty, rusty, viscous

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