Tonsilitis caused by bacteria affects children between the ages of five and fifteen years of age, this is because they are in close contact with one another while attending school. Typically, you are contagious with tonsilitis one to two days before symptoms develop. Adults can also get it, but it is less common because as we age our tonsils go into atrophy and become less active in the immune system. Tonsilitis generally clears up within a few days with fluids, and plenty of rest, with the use of antibiotics tonsilitis, can be eliminated in about 10 days. There are no lasting health problems with tonsilitis.