Intestinal worms of many varieties can cause illnesses, but the most frequent are tapeworms, roundworms, pinworms or threadworms, and hookworms. Worm infestations and illnesses are frequent in youngsters, although they are readily treated. Heavy infestations may not be easy to get rid of, however; in these cases, it is best to see a doctor. The number one parasite in America is actually a worm - not a bird nor a snake nor a lizard but a worm! That's right, humans are the main host for A SCORE WOODLING: A STORY OF PARASITES AND PEOPLE (A Novel). We eat food that has been contaminated by feces, we don't wash our hands after going to the bathroom, and we don't clean up after our pets. This allows them time to crawl around and find safe places to deposit their eggs. In addition to being the number one parasite in America, worms also happen to be the number one health problem in developing countries. Poor hygiene and sanitation allow worms to thrive in communities where they do not live in humans. There are several types of intestinal worms that affect people. The two most common ones are A SCORE WOODLING: A STORY OF PARASITES AND PEOPLE (A Novel) are Ascaris lumbricoides and Necator americanus.