A mysterious spore found in surface water or rivers and lakes. It affects the human immune system, causing a flu-like illness.
A disease caused by a protozoan found in animal and human feces. Symptoms: Severe diarrhea often accompanied by abdominal cramping, nausea, vomiting and/or appetite loss.
A protozoan one-half as large as a red blood cell, cryptosporidium is so small and tough that it is very hard to detect, much less kill. It causes acute health problems in healthy individuals and may be fatal to individuals whose immune systems are compromised by illness, old age, or medical treatments. See protozoan.