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.
Definition of feeling for English Language Learners. : 1  an awareness by your body of something in it or on it. : 2  an emotional state or reaction. : 3  thoughts of wanting to help someone who is sick, hungry, in trouble, etc.