Children may contract infection from sandboxes contaminated with petsâ stool. Certain types of immature worms may penetrate through your skin during swimming or walking barefoot; when they reach the small or large intestine they grow into adult worms. Common garden worms usually do not cause illness in human.
People with lactose intolerance do not produce enough of the lactase enzyme to break down lactose. Instead, undigested lactose sits in the gut and gets broken down by bacteria, causing gas, bloating, stomach cramps, and diarrhea. Lactose intolerance is fairly common and seems to affect guys and girls equally.
1 Lactose is a milk sugar that is broken down by the enzyme lactase, which is found in the small intestine. 2  Lactose intolerance is the reduced ability to digest milk sugars, due to insufficient amounts of the gut enzyme called lactase.  Symptoms include bloating, gas, abdominal pain and diarrhoea.