Pneumocystis carinii is an unclassified protozoa emerging as a distinct pathogen for those who are immunocompromised – especially those with AIDS. The microorganism is acquired through inhalation into the respiratory tract, where the trophozoites attach themselves to pulmonary tissue cells. Symptoms include the following: dry cough, fever, weight loss, fatigue, night sweats, and difficulty breathing. This amoeba causes a type of pneumonia that often causes death by asphyxiation in immunocompromised patients and premature babies.