Plague

Plague (pestis) is an acute zoonotic natural-focal infectious disease with a predominantly transmissible mechanism of transmission of the pathogen, which is characterized by intoxication, damage to the lymph nodes, skin and lungs. It is referred to especially dangerous, conventional diseases.

Symptoms of plague consist either of acute pneumonia, or massive lymphadenopathy with high fever. The latter often progresses to septicemia. Diagnosis of plague is based on epidemiological data and clinical examination. Confirmation of the diagnosis is based on a culture test. Treatment of plague is carried out by fluoroquinolone or doxycycline. 

ICC codes 10

• A20.0. Bubonic plague.
• A20.1. Cellular-skin plague.
• A20.2. Pneumonic plague.
• A20.3. Plague of meningitis.
• A20.7. Septic plague.
• A20.8. Other forms of plague (abortive, asymptomatic, small).
• A20.9. Plague, unspecified.

What causes plague?

The plague is caused by Yersinia pestis. Yersinia (formerly Pasterella) pestis is a short bacillus that often stains bipolar (especially with Giemsa dye) and can resemble an English pin.

The plague originates primarily in wild rodents (eg, rats, mice, squirrels, prairie dogs) and is transmitted from the rodent to humans through the bites of infected fleas. Transmission of infection from a person to a person occurs when inhaling an air suspension, which is formed in patients with a pulmonary form of the plague (primarily pulmonary plague). The latter is a highly contagious disease. In the endemic regions of the United States, a certain number of cases can be caused by domestic animals, in particular cats. Transmission from cats can occur through bites or by inhalation of air suspension (if the animal is sick with a pulmonary form of plague).

In the past, there were massive epidemics of plague (for example, black death of the Middle Ages). Recently, the plague was recorded in the form of sporadic cases or limited outbreaks. In the US, more than 90% of the plague cases occur in the south-west of the country, especially in New Mexico, Arizona, California and Colorado. Yersinia is considered as a possible weapon of bioterrorism.

What are the symptoms of plague?

The most common form of the disease is bubonic plague, the incubation period of which is usually 2-5 days, but it can vary from a few hours to 12 days. The onset of fever (39.5-41 ° C) is acute and often accompanied by chills. Pulse may be rapid and threadlike; hypotension often develops. Enlarged lymph nodes (buboes) appear with fever or shortly before it begins. The first to enter the pathological process are the femoral or inguinal lymph nodes, after which axillary, cervical or multiple lymph nodes are affected. Usually the nodes are extremely sensitive and are surrounded by an edema zone. They can fester at the second week of the disease. The underlying skin is smooth and red, without raising the local temperature. In some cases, a primary skin damage can occur at the site of the bite, which can be a small bubble with a minor local lymphangitis and a scab. The patient can be restless, delirious, his consciousness can be confused, and coordination impaired. The liver and spleen can be enlarged.

The incubation period of the primary pulmonary plague lasts 2-3 days, after which the disease takes an acute course. At the same time there is a high fever, chills, tachycardia and headache, which is often acute. Initially, cough is insignificant, but it develops within 24 hours. The sputum is initially mucous, but soon there appear veins of blood in it, after which it becomes pink or bright red (resembling a raspberry syrup) and frothy. There are tachypnea and dyspnea, but there is no pleurisy. Symptoms of compaction of the lung tissue are rare, wheezing may be absent.

Septicemic plague usually appears along with the bubonic form as an acute, fulminant disease. Abdominal pain, most likely due to mesenteric lymphadenopathy, occurs in 40% of patients. Pharynx plague and plague meningitis are less common forms of the disease.

The small plague is more benign than the bubonic form. It usually occurs only in endemic regions. Lymphadenitis, fever and prostration are reduced within a week. The mortality rate in untreated patients is about 60%. Most of the deaths occur as a result of sepsis within 3-5 days. Most untreated patients with pulmonary plague die within 48 hours of the onset of symptoms. Septicemic plague can be fatal until signs of bubonic or pulmonary form of the disease appear.

How is plague diagnosed?

The plague is diagnosed on the basis of staining and culture. Usually, the material for research is taken by needle aspiration from bubo (surgical drainage can promote the spread of MO). It is also necessary to conduct a culture of blood and sputum. Other tests include immunofluorescence staining and serological tests. A titer of more than 1:16 or a 4-fold increase between acute and convalescent titers is considered positive. If possible, the diagnostic is PCR analysis. Previous vaccination does not rule out plague; Clinical disease can develop in vaccinated people. Patients with pulmonary symptoms or signs should undergo chest radiography, which shows a rapid progression of pneumonia with pulmonary plague form. The number of leukocytes is usually 10-20 x 109 with a huge number of immature neutrophils.

How is the plague treated?

Immediate treatment of plague reduces mortality to 5%. With septicemic or pulmonary plague, treatment should be started within 24 hours. At the same time, streptomycin 7.5 mg / kg intramuscularly is used every 6 hours for 7-10 days. Many doctors prescribe higher starting doses up to 0.5 g intramuscularly every 3 hours for 48 hours. An alternative drug is doxycycline 100 mg intravenously or orally every 12 hours. Gentamicin may also be effective. For plague meningitis, chloramphenicol should be given in a loading dose of 25 mg / kg intravenously, after which the treatment should be continued at a dose of 12.5 mg / kg intravenously or orally every 6 hours.

Routine isolation is sufficient in patients with a bubonic form of plague. Patients with primary or secondary pulmonary plague require strict respiratory isolation. All persons who were in contact with a plague patient should be under medical supervision. They should measure body temperature every 4 hours for 6 days. If the latter is not possible, tetracycline can be given at a dose of 1 g once a day for 6 days, but this can lead to the emergence of antibiotic-resistant strains.

The plague can be prevented through the supervision of rodents, and the use of insect repellent substances to reduce flea bites to a minimum, vaccination against plague is also used . Travelers should receive a prophylaxis with doxycycline 100 mg orally every 12 hours during exposure periods.