Name a risk factor for developing an opportunistic infection in HIV patients.

In HIV patients, low CD4 T-cell counts are a significant risk factor for developing opportunistic infections. CD4 T-cells play a crucial role in the immune system by helping to coordinate the immune response against infections. HIV targets and gradually destroys these cells, leading to a weakened immune system.

When the CD4 T-cell count drops below a certain threshold (typically below 200 cells/mm3), the body becomes increasingly vulnerable to infections that would not normally cause illness in individuals with a healthy immune system. This makes individuals with low CD4 counts susceptible to various opportunistic pathogens, such as specific bacteria, fungi, and viruses.

In contrast, high CD4 T-cell counts generally indicate a stronger immune response, recent vaccinations can boost immunity but are not a direct correlation to opportunistic infections, and good nutritional status supports overall health and immune function rather than being a risk factor by itself.