If its recommended for water to boil to ensure its safety, how is it?
A fever of 38C does not cripple or kill these microorganisms. They are quite healthy at that temperature. An infection is a race. The microorganisms are multiplying and your immune system is developing antibodies to block their ability to infect cells and to neutralize any toxins produced by them. The race is to create these antibodies in time before the microorganisms kill you. Many microorganisms multiply a bit slower at the higher temperature giving your body more time to make the antibodies.