Ever wonder how many germs it takes to give you an infection?

If you're planning to catch shigellosis, then just ten microscopic bacteria will do the trick.

Since Shigella is passed through "fecal/oral" contamination, a typical infection might occur during a visit to a local restaurant, where a rushed attendant returns from the bathroom to prepare your salad and accidentally leaves a smear of human excrement on the wet lettuce. A fingerprint is enough.

Three days later you will get the definite feeling something is very wrong. Crampy abdominal pain, fever and severe, continuous diarrhea containing bloody mucus. Close relatives of the E-Coli that normally fill your gut, the Shigella bacteria use molecular harpoons to inject shiga toxin into the wall of your digestive tract, allowing them to directly invade your body and produce massive intestinal damage that will put you in bed for a week. Anti-diarrhea medicines can make you even sicker by limiting the body's natural tendency to flush out the infection. Complications can include seizures, kidney failure, chronic arthritis or even death.

The dysentery is compounded by tremendous fatigue and dehydration that turns a six-hour emergency room visit into torture. The wait might be worth it -- the diagnosis can be made through stool culture, intravenous fluid is a miraculous restorative, and the infection often responds quickly to antibiotics. But don't expect to be immune to future infections -- there are over 40 serotypes.

Still want to eat out? If you don't see any soap in the bathrooms, skip the vegetarian fare -- or order your salad cooked at over 400 degrees.