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.
feeling, emotion, affection, sentiment, passion mean a subjective response to a person, thing, or situation. feeling denotes any partly mental, partly physical response marked by pleasure, pain, attraction, or repulsion; it may suggest the mere existence of a response but imply nothing about the nature or intensity of it.