What Are the Causes of Intestinal Parasites?

Intestinal parasite infections can occur in people of any age, and babies, the elderly and pregnant women are at a higher risk of becoming ill when infected. Intestinal parasites can cause symptoms such as nausea, vomiting, diarrhea, itching, anemia and bleeding, and intestinal parasite infection in babies may be life threatening.

Animals

• Contact with animals, including their waste can be a source of intestinal parasites, according to the Mayo Clinic. Petting zoos and pet shops may have animals including reptiles, fish and rodents that are infected with intestinal parasites, which can infect humans who pet or handle them. Allowing household pets to go outdoors can result in them coming into contact with other animals infected with parasites, and the pets can bring the parasites into the home to infect their owners.

Food

• According to the Mayo Clinic, contaminated food and drinks can be a source of intestinal parasites. Food that is undercooked or eaten raw can contain worms, eggs or cysts that develop into parasites such as worms and washing foods with contaminated water can expose them to uncontaminated food. People who prepare food without washing their hands may contaminate food with fecal matter containing parasites.

Physical Contact

• Direct physical contact with intestinal parasites can result in infections, according to the Mayo Clinic. Babies and toddlers with parasites may expel them into their stool, which can contaminate diaper changing areas and infect others. Touching soiled clothing that have parasites on them can also result in infection.

Sexual Contact

• Certain types of sexual contact may result in infection with intestinal parasites, according to the American Academy of Family Physicians. Anal intercourse can allow parasites such as giardia to spread between people. Oral sex or vaginal sex that follows anal intercourse can also allow for the spread of intestinal parasites.

Soil

• Exposure to soil that is contaminated with the eggs, cysts or adult intestinal parasites can be a cause of infection, according to the American Academy of Family Physicians. Soil that is fertilized with human or animal waste may contain parasites such as hookworms, which can enter the body through the skin and infect the intestines. Walking on soil with bare feet can result in small cuts or abrasions that can allow parasite eggs or cysts to enter the body and cause intestinal infections.

Water

• Water contaminated with sewage including human or animal feces is a cause of intestinal parasites, according to the National Library of Medicine. Swimming in a creek, river or lake may cause infections with intestinal parasites such as giardia or schistosoma. Walking through mud or puddles without proper footwear can also allow worms to enter the body through the skin which then infect the intestines.