Risk factors for parasites include children who play outdoors in the dirt, close contact with pets, farming, gardening, outdoor activities that include walking near wooded areas, digging in the dirt, walking outside barefoot, being in close or sexual contact with someone who has specific parasites, or sometimes simply the act of walking from the car to the house. Parasites exist in the world and can not be avoided simply by avoiding being outdoors. Parasites can be found in foods, especially undercooked or exotic foods. 

Physicians typically do not screen for parasites without cause. Blood tests or fecal samples can determine parasites, but not all parasites. Pinworms require a nightly anal test, typically for three nights, where a sticky slide is placed on either side of the anus to pick up any eggs that have been laid. Analyzing the slide under a microscope can determine the presence of pinworm. 

The majority of parasitic diseases are not dangerous. However, extreme cases may cause weight loss, dehydration from chronic diarrhea, symptoms which mimic pneumonia, anemia, fatigue, Lyme disease from ticks, Malaria from mosquitoes, or a host of uncomfortable bowel syndromes.