这大概是人们相信孕妇不应该养猫的道理：
Can your cat make you crazy?
Dr. E. Fuller Torrey, president of the Stanley Medical Research Institute in Bethesda, Md., has been studying whether a parasite found in cat droppings called Toxoplasma gondii can trigger an onset of schizophrenia later in life.
"Most people have not thought of schizophrenia as being caused by a virus or bacteria or a parasite," Torrey said. "This is a relatively new idea."
It's long been established that the parasites found in cat droppings are a health risk to pregnant women and young children, but whether the cat can be directly linked to schizophrenia remains to be seen.
"We haven't proven anything," Torrey said. "Infectious agents, virus, etcetera really need to be looked at very carefully in these cases."Torrey's study found a 53 percent increase in risk for schizophrenia if you owned a cat during childhood, but he also found a 51 percent increase in risk if you were breastfed. Statisticians believe the increase in risk has to be above 200 percent for there to be an actual association between something like owning a cat and schizophrenia.
In the meantime, Torrey is still cautious of cats.
"Personally I would not buy a kitten for a small child," he said. "I don't think we know enough to be able to say there's no risk."
ABC medical contributor Dr. Tim Johnson said he is skeptical of the study, but said there are diseases people can get from cats, the most serious being toxoplasmosis. Johnson said millions of people are affected with this parasite, but their immune system fights it off.
Johnson added, however, that pregnant women, women who are about to become pregnant and people with weakened immune systems, including those who are undergoing chemo or have AIDS, should avoid cats and cat litter
原文在此：
http://abcnews.go.com/GMA/OnCall/story?id=1299317#.Tz1Za8Ugq-0