Signs, symptoms, and pathophysiology of Pneumocystis carinii pneumonitis.

In 80 patients with Pneumocystis pneumonitis, the intial signs and symptoms of infection were usually fever and cough, followed by tachypnea and coryza. Flaring of the nasal alae and cyanosis occurred later. Blood gas composition was markedly altered in its acid-base profile in most patients at admission. There was moderate to severe respiratory alkalosis and hypoxia. Clinical manifestations were correlated with the extent of histopathologic changes in the lung. (Deprivation of protein in the diet of rats provoked P. carinii infection.) P. carinii infection was found in children with kwashiorkor; evidence of protein-calorie malnutrition is closely associated with P. carinii pneumonitis in children wiht cancer and other primary diseases. P. carinii pneumonitis proved unique in that the causative organisms remained limited to the lungs even in fatal cases. No toxins have been identified, and systemic effects of the infection were only those that could be related to hypoxia and fever.