Answer:
Epstein-Barr virus
Explanation:
Epstein-Barr virus (EBV) is most widespread in the human population. It spreads through bodily fluids such as saliva. EBV is the virus which can cause or affect infectious mononucleosis also known as mono and other illnesses. After you get infected by EBV, the virus become inactive in our body. In some cases, virus may reactive, peoples who's having weak immune system are more likely to develop symptoms if virus is reactive.
Symptoms: Symptoms of EBV includes Fever, swollen liver, rash, enlarged spleen etc.