Primary pneumonic plague is a lung disease characterized by destruction of alveoli and perivascular pulmonary interstitial foci. This form of plague occurs during the first three weeks after infection with the plague bacteria. Clinical signs of primary pneumonic plague include rapidly developing fever, shortness of breath, pleural pain, cough and other symptoms of influenza and pneumonia. Secondary pneumonic plague. - an infection that quickly spreads from the pleura to the lungs. It is caused by hematogenously penetrating through the branches of the pulmonary artery from endocardial vegetations rod-shaped or coccal microorganisms or their spores, as well as pieces of disintegrated lung tissue.