The human body is its own ecosystem; millions of bacteria and organisms call it home. Usually the body exists in symbiosis with these organisms, some of them provide benefit. Other organisms, parasites, provide no benefit and are usually harmful. Parasites are similar to fleas or ticks on a dog, but inside your body. They live in and attach to our intestines; they absorb nutrients, lay eggs, and excrete toxic waste (formalin, isopropal alcohol and formaldehyde) inside us.
The risk of infection is widespread. It is estimated that more than 90% of all Americans are infected with some type of harmful organism. Infection can come from “benign” activities like eating at a restaurant, owning a pet, or having a child in school or daycare. Food handlers can spread parasites through unsafe or unclean practices. Pets can pick up parasites from insect bites and introduce them into the home. The undeveloped hand washing skills and curiosity of children usually leads to lots of indirect contact with every type of infectious agent. Soldiers, travelers and workers returning from overseas often bring internal parasites with them as a result of eating or drinking contaminated food in other countries. Plumbers, sanitation engineers, and outdoor workers are also more likely to come into contact with harmful organisms.
Common Harmful Organisms:
- Pinworms are very common in the United States. Adult pinworms live in the colon and can remain there for months. Female pinworms leave the host through the anus and lay eggs on the skin. Pinworms cause itchiness and irritation around the anal area, and they are often spread because the infected person (usually children) scratches the area and touches another surface. Eggs left on clothing or bedding can be ingested through direct contact with the mouth or while breathing. Eggs can survive up to three weeks outside the human body.
- Hookworms occur in soil or water and can be ingested by eating unwashed produce or drinking contaminated water. Infection may also happen through open wounds, especially in areas where there is animal feces. Hookworms use their teeth to attach themselves to the intestinal wall and siphon blood. They can cause anemia, weight loss, and malnutrition.
- Roundworms are the most common harmful organism in the world. Female roundworms enter the small intestine as larvae and can grow to over a foot long. Infection is spread through ingestion of fecal matter, not person-to person contact. Infection may be asymptomatic, although heavy infestations could cause intestinal blockage.
- Tapeworm infection happens by swallowing an infected flea and, though rare in humans, can be serious. Symptoms include dizziness, confusion, and fatigue.
- Liver Flukes are a worm that cause irritation and holes in the liver. Eating undercooked fish or swimming in contaminated water causes liver fluke infections. Symptoms include fatigue and/or pain on the right side of the body, below the ribs.
- Giardia is a widespread protozoa that causes diarrhea. Giardia lives in the intestines and is passed in the feces. It can be spread months after it is out of the body. Infection may occur by ingesting contaminated water. Hygienic food handling practices can reduce the risk of infection.
- Entamoeba is a single cell parasite. Its infection, called amebiasis, often causes mild, or no, symptoms but in rare cases can cause liver abscesses.
- Cryptosporidium infection occurs by swallowing water that has been contaminated. The infection is called “crypto” and causes diarrhea.
- Toxoplasmosis is caused by handling cat litter or undercooked meat (this is why pregnant women are warned against cleaning cat litter boxes). Toxoplasmosis is third among deaths attributable to food borne illness. Infection is often asymptomatic, but can cause severe reactions in pregnant women and people with compromised immune systems. Infection can cause seizures, confusion, loss of coordination, and death.
While prevention is always recommended, living in a bubble is not realistic. Almost all of us will come into contact with these harmful invaders over the course of our lives, if we’re not infected already. Since these infections often have no outward symptoms, it is not always obvious that something is living inside you, feeding off of your tissues. Symptoms may be as vague as fatigue or gas.