Can you elaborate? I haven't read too much about it. Is it something that affects you for years?
All people are believed to be susceptible to infection, but individuals with a damaged or undeveloped immunity may suffer more severe forms of the disease.
...it seems possible to me that, if Giambi had been using steroids and suddenly stopped (as is the speculation) his immune system could have been weakened enough that this affected him more than it normally would.
Since he is treated now, Giambi is in better shape than most. What strikes me is that he's had this condition for months before they are finally testing him for this particular parasite. He risks possible liver and intestinal damage and also this could trigger illnesses like ulcerative colitis. That would be a nightmare.