41.   How many anthrax spores does it take to cause illness?

42.   How many organisms it takes to cause illness depends on the person.

43.   In healthy people, it lives silently in the intestinal tract, causing no illness.

44.   In earlier studies, dregs of communion wine have grown organisms like Mycobacterium avium, one of many microbes that can cause devastating illnesses for people infected with HIV.

45.   In all but a few instances, illness has been caused by undercooked hamburgers.

46.   In many, the immune system clears the virus without causing illness.

47.   Infected gums can easily transmit bacteria to the blood stream, causing serious illness.

48.   It is not considered lethal, even after long exposure, but it could cause illness or have uncertain long-term effects.

49.   It never goes away but rarely causes any illness either, unless the immune system fails.

50.   It must not be the presence of germs that causes illness, she said, but the absence of an adequate defense from the immune system.