- Clinical diagnosis of Pneumocystis jiroveci pneumonia will be made by one of the study investigators. All infants must be HIV ELISA positive or exposed, have an oxygen requirement (saturations on air < 90%) and have severe respiratory distress and cough. They may also have a low grade fever, clear chest or diffuse signs on auscultation and features suggestive of Pneumocystis jiroveci infection on chest radiography.