i read in a book somewhere that if someone has an infection or disease such as syphilis, then by giving them another disease thing such as malaria can over-ride the syphilis and they wont have it anymore.

is that possible?

Before the invention of antibiotics some doctors advocated the practice of inducing high fevers in people with late phase syphilis. Malaria was used because it was easily (kind of) cured with quinine. The idea was that by prolonging a high fever the bacteria would be slowed. This was dangerous because the strain on the body was significant. Modern drugs work better and are less dangerous.

some times it can so happen that the commensels in the body can take advantage of the situation and the condition might actually get from bad to worse.with the protozoan the bacteria and the commensels all trying to establish their authority.