My niece has a problem with worms in her system. They have been to doctors and have been given medications for them. They have given stool samples but doctors say they find nothing by time they get the sample. My brother can see these worms in her stools . They keep coming back. She is the only one getting them in the house. She may not be getting rid of them each time she has taken medication for them. What should my brother do and what kind of doctor should he see. The doctors he has seen for this has pretty much stopped helping to find out what is causing the relapses.