Do you always need special stuff to get rid of parasite

My daughter had worms about 2 years ago and went to the docter,she must have got it that time from somebody in University.
She had to bring in her stool to be diagnosed.They thought it tested positive when it came back from the lab but were not sure.
The doctor didn t give her anything for it but told her to come back in another couple of weeks to get her stool tested again.
This time it came back negative.
Can it happen that the body had removed it itself?
Or do you think she should take still treatment for it? Tweet