Opportunistic infections (OIs) are infections that occur more frequently and are more severe in individuals with weakened immune systems, including people with HIV.
Being nostalgic means to miss the past time. It seems that a real life was in the past because now in the present is different, probably things changed and we know that never is going to be the same. It leads to a nostalgic feeling.
Anxiety is a feeling of unease, worry or fear. Everyone feels anxious at some point in their life, but for some people it can be an ongoing problem. A little bit of anxiety can be helpful; for example, feeling anxious before an exam might make you more alert and improve your performance.