Pathology and pathogenesis of plague

Infection can occur through the skin (by the bite of fleas, rubbing crushed fleas or their droppings in the intact skin or infected material), the respiratory tract and the conjunctiva. The plague microbe, once in human skin, quickly penetrates into the regional lymph nodes. Inflammatory reaction in the skin (the place of the entrance gate) and the lymph vessels is rare. In some cases, the skin occurs primary affect - pustule or carbuncle with serosanguineous content. In subsequent ulcers, the bottom of which is impregnated hemorrhagic fluid. When the healing of ulcers granuliruth and subcourse.
Often the process begins immediately after the regional to the place of the entrance gate lymph nodes (primary plague bubo first order). At the further spread of the pathogen through the lymphatic vessels in the process can involve new groups of lymph nodes (primary plague bubny second, third order, and so on). Primary bubny formed in the inguinal, femoral, armpit, the neck, the submandibular and other lymph nodes. In the result of haematogenous entry of agent or of its toxins in remote lymph nodes may develop secondary plague of Bubnov. In arterioles, even deleted from pathological foci are destructive changes in the form of plasma impregnation and fibrinoidnogo necrosis. Many investigators in the pathogenesis of plague attach great importance to the damage of the vessels.
The point is that the skin in the area of primary Bubnov tense, bluish-red. At level two visible dark red enlarged lymph nodes, their boundary lubricated. The surrounding tissue edema, imbibition blood (printing. table, Fig. 3). Sometimes visible grey and grey-yellow foci of necrosis. In the primary bubonic of the second order and on secondary bubonic the same picture is observed, they only rarely necrosis and Perederiy.

axillary bubo when plague
Fig. 3. Axillary bubo when plague; lymph nodes, and fiber impregnated with blood.

Microscopically, the affected lymph nodes and surrounding tissue soaked serosanguineous the exudate, in the subsequent character of the exudate is changing, and it appears in a large number of neutrophilic leukocytes. Along with the changes of the exudate marked proliferation of lymphocytes, reticular and endothelial cells. In slices, even during normal color, found a huge number of plague bacilli (Fig. 3). The process bubonic ends purulent fusion or gangrene. The favorable outcome occurs sclerosis. Bubonic form of plague may be complicated by secondary plague pneumonia.

Fig. 3. The abundance of plague bacilli in the primary bubo.
Fig. 4. Serosanguineous pneumonia and pulmonary form of plague.

When primary pulmonary plague lung damage tends to be focal nature (bronchopneumonia). Pneumonic lesions may merge, affecting almost the entire share (pseudosabina pneumonia). Less inflammatory process captures a percentage or more shares. Pneumonic tricks dense on palpation, grey-red or gray color, the cut surface is smooth. No pronounced grain in share lungs helps to differentiate primary pulmonary plague from lobar pneumonia. From the cut surface of the lungs flows down the muddy, bloody pussy or liquid. Pleura hyperemic, with bleeding, sometimes with soft overlays, fibrin. In the pleural cavities found serosanguineous exudate. Microscopically, the alveoli are filled serosanguineous exudate (Fig. 4)that contains a large number of the pathogen. Among the dead after 36-48 hours. after the outbreak of the disease in the exudate find leukocytes. On separate sites lung tissue blackened dead tissue. Sometimes develops the so-called pulmonary type of pneumonia with hyperemia and oedema of the lungs. This form of pneumonia is usually considered as a manifestation of lightning plague of sepsis.
The use of sulfa drugs and antibiotics (streptomycin) led to changes in the morphology of primary pulmonary plague. Antibiotics inhibit fibrinolytic properties of the pathogen, so the exudate appears fibrin, and then pneumonia assumes the character of an interstitial with the subsequent outcome sclerosis.
In addition to local changes, in all forms of plague found bleeding in the form of petechiae and Achkasov on the peritoneum, pleura, pericardium, the lining of the stomach and other organs. In parenchymatous organs develops granular dystrophy, can be formed necrosis. Spleen increased in 1,5-2 times, flabby, the pulp is dark-red, gives ample scraping. Pia mater swollen, red-blooded, with hemorrhages. Swelling and haemorrhages occur in the brain and nerve ganglia.