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.
Very interestingly, lonely individuals described a feeling of being lost, and not knowing where they are going. Other metaphorical words include things like darkness, night, blinded, drowning, clueless, and lack of meaning.