In patients with AIDS, which opportunistic infection is frequently associated with CD4 counts below 200?

In patients with AIDS, Pneumocystis pneumonia (PCP) is an opportunistic infection commonly associated with CD4 counts below 200 cells/mm³. This infection is caused by Pneumocystis jirovecii, a fungus that can lead to life-threatening pneumonia in immunocompromised individuals. The risk significantly increases as the CD4 count declines, placing patients with AIDS at a heightened risk when their CD4 levels fall below that critical threshold.

Patients with CD4 counts under 200 are particularly susceptible to PCP because their immune system is severely compromised, inhibiting their ability to mount an effective response against such opportunistic pathogens. Clinical signs of PCP may include non-productive cough, dyspnea, and fever—symptoms that can rapidly evolve without appropriate prophylaxis or treatment.

While other opportunistic infections can occur in patients with AIDS, they are associated with different thresholds of CD4 counts or have varied risk profiles. For instance, Cytomegalovirus retinitis is often seen with CD4 counts below 50, and other diseases like histoplasmosis or tuberculosis present different risk factors related to opportunistic infection surveillance and prevention strategies. Understanding the specific risks associated with various CD4 levels is crucial for effectively managing the health of patients