Aerosols in the Treatment of Asymptomatic Pneumocystis Pneumonia: A Pilot Study Assessing the Effectiveness of Aerosolized Pentamidine as Treatment of Subclinical Pneumocystis Infection in Patients With No Clinical Symptoms

Inclusion Criteria Concurrent Treatment: Allowed during aerosolization: Metaproterenol or albuterol to treat bronchospasm. Patients must have: * HIV infection confirmed by ELISA, HIV culture, or p24 antigenemia. * Suspected subclinical Pneumocystis carinii infection as detected by \> 10 percent change in lung volumes and/or diffusing capacity indicative of progressive restrictive disease as detected by monthly screening pulmonary function tests (PFT's). Patients will be afebrile and have no respiratory signs or symptoms of clinical disease. Morphologic confirmation of pneumocysts will be determined by bronchoalveolar lavage (BAL) performed 24 hours after the initial aerosol inhalation. If the BAL is negative for pneumocysts, the patient will be withdrawn from this protocol and will be followed per the screening PFT protocol at Stony Brook. * Diagnostic bronchoscopy and BAL must be performed within 2 weeks of detection of \> 10 percent change in PFTs. * Ability and willingness to sign informed consent. Prior Medication: Allowed: * Primary prophylaxis with agents active against Pneumocystis carinii pneumonia (PCP), but no more than 5 patients may have received prior prophylaxis with aerosolized pentamidine. * Zidovudine. Exclusion Criteria Co-existing Condition: Patients with the following conditions or symptoms are excluded: * History of Pneumocystis carinii pneumonia (PCP). * Development of respiratory signs and/or symptoms in the interval between detection of pulmonary function test (PFT) abnormality and the time of initial aerosol deposition. * Dyspnea, cough, or bronchospasm that prevents cooperation with aerosol administration. * History of a major adverse reaction to pentamidine defined by absolute neutropenia, \< 750 polymorphonuclear leukocytes plus bands; thrombocytopenia, \< 40000 platelets; creatinine rise, \> 3.0 mg/dl; liver function abnormalities, SGOT or SGPT \> 5 x normal; hypoglycemia, \< 50 mg/dl; rash, exfoliative or mucositis; cough, unremitting cough or bronchospasm uncontrolled by bronchodilator preventing \> 50 percent of dose delivered for \> 2 days. Concurrent Medication: Excluded: * Zidovudine. Patients unable to cooperate with aerosol administration are excluded. Prior Medication: Excluded: \- Another antiprotozoal regimen for this episode. Unable to complete therapy or follow-up for social reasons in the opinion of the investigator.