How long does it take for any symptoms to appear? Well, the answer to this question is a tough one. There are many things which may influence the onset of symptoms for this particular disease. Symptoms may appear within hours or may appear only after several days. It is for this reason that if diarrhea occurs, one should examine the stool for blood, and pay attention to any other symptoms which may occur, particularly if the person affected is a young child, is elderly, or is infirm in any way. The following are some of the things which can influence the time it takes for symptoms to occur: (1) The actual number of organisms ingested - the higher the number ingested, the sooner the possibility for symptoms (the relatively greater concentration of toxin made). (2) The health status of the individual - the weaker or less healthy, the sooner the possibility for symptoms. (3) The individual's natural resistance to either      (a) the growth of the organism within the intestine, or      (b) the effect of the toxin itself. Different    people may respond differently. Usually, the disease is self-resolving (means that the disease clears "on its own") within about 8 days or so. However, as stated above, if any blood appears in the stool, or if watery diarrhea appears in an infant or a small child, one should immediately contact one's physician and describe the symptoms as accurately as possible. Whether or not E. coli O157:H7 is involved, diarrhea for any reason in a little kid can potentially be dangerous - so - discuss the symptoms with your physician if you are the least bit concerned. How can I reduce the risk of infection from E.coli O157:H7? 1. Always clean any surface that has come in contact with raw meat, before any other item is placed on that surface. 2. Always thoroughly wash your hands after handling raw meat, and before you handle any other utensils or other food items. 3. Never use the same plate, tray or utensils for the cooked meat that you use for the raw meat - unless you thoroughly wash the plate, tray or utensils in-between. 4. Always cook meat, _especially_ ground meat, until the juices run absolutely clear - pink _is not_ good enough. In fact, it is necessary for the internal temperature of a hamburger pattie to reach 160 degrees F to kill all of any contaminating E. coli. 5. In day-care centers, schools, etc., any small children with diarrhea should be carefully handled, and kept separate from all well children. All diapers, and any soiled clothing should be kept separate from all well children. The day-care worker, teacher, and health-care personnel should practice strict hygeine at all times, regardless of the health of the children. The best advice is to of course be smart about all of this... realize that there is always a risk and simply take common-sense actions to minimize the risk. . Copyright John C. Brown, 1995, updated September 16, 1997.