Carinii

Carinii, often referred to as Pneumocystis jirovecii pneumonia (PCP) when discussing the associated disease, is a genus of fungi. Historically, it was mistakenly classified as a protozoan. The most well-known species within this genus is Pneumocystis jirovecii, which is a significant opportunistic pathogen. This fungus resides in the lungs of a wide range of mammals, including humans. In healthy individuals with competent immune systems, Pneumocystis infection is typically asymptomatic and remains dormant.

However, in individuals with weakened immune systems, such as those with advanced HIV/AIDS, organ transplant recipients, or those undergoing chemotherapy, Pneumocystis can proliferate and cause a severe form of pneumonia. This condition, Pneumocystis pneumonia (PCP), is characterized by symptoms like fever, dry cough, shortness of breath, and chest pain. Diagnosis usually involves identifying the organism in respiratory specimens, such as sputum or bronchoalveolar lavage fluid, through microscopy or molecular methods. Treatment typically involves specific antimicrobial medications like trimethoprim-sulfamethoxazole. Preventive measures, such as prophylactic medication, are often recommended for individuals at high risk of developing PCP. The exact mode of transmission is not fully understood but is believed to occur through airborne droplets.