What is the primary opportunistic infection associated with AIDS?

Pneumocystis jiroveci pneumonia (PJP) is indeed the primary opportunistic infection associated with AIDS, particularly in patients with a CD4 count of less than 200 cells/mm³. PJP is caused by a fungus that is frequently found in the environment; however, in immunocompromised individuals, especially those with severe immune deficiency like in AIDS, it can lead to a significant and life-threatening form of pneumonia.

Patients with AIDS are at increased risk for a variety of opportunistic infections due to their compromised immune systems. PJP is often one of the earliest infections to manifest as individuals transition into AIDS from HIV infection, marking a critical threshold of immunosuppression. The symptoms of PJP include progressive dyspnea, dry cough, fever, and it typically presents with diffuse interstitial infiltrates on chest imaging.

While other opportunistic infections such as cytomegalovirus, tuberculosis, and histoplasmosis are important in the context of AIDS, they present under different immunocompromised states or with specific risk factors. PJP remains a classic and defining infection closely associated with the advanced stages of HIV disease, underscoring the importance of prophylactic treatment in at-risk populations to prevent its occurrence.