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The symptoms your friend is having is most likely due to flu. Influenza
, commonly known as "the flu," is a highly contagious viral
infection of the respiratory tract.
Although he might not be having fever & feeling well enough to play tennis but still he is contagious till all his symptoms gets resolved.
It usually takes one week from the start of symptoms to get it resolved completely. One is contagious for viral flu 1 day before symptoms begin to approximately 5 days after illness onset.
As he is still having the symptoms & its just 2 days from his symptoms,he is still contagious.If you will play now,you may catch the infection & get the viral flu symptoms.
You will be safe to play after tuesday(5 days from when the symptoms first appear).
Hope this helped.
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