A few weeks ago, a mountain biker I know found something that looked like an undigested noodle in the toilet after he had a bowel movement. He captured the thing and headed to the doctor. At first glance, the doctor suspected that he had a tapeworm. Though this rider had been out of the country around six months earlier, the doc didn't think the creature was picked up outside of the U.S.A. The doctor told him that he may have gotten it from ingesting dirt—as in the dirt that gets on water bottles during mountain biking.
This cyclist's experience reminded me of professional cyclist Ben Day, who removed a four-foot tapeworm from his body a couple of years ago. Of course all of this got me wondering exactly how easy it is to get tapeworms. Specifically, am I at risk?
I contacted internal medicine specialist Dr. Peter Smith and asked him questions about these disgusting creatures. Here is what Dr. Smith had to say:
As athletes tour the globe and press deeper into natural areas, they expose themselves to many risks. Part of the challenge of competition includes the exposure to exotic and rugged environments. As competitions draw these athletes into wilderness and underdeveloped locations, the risk of exposure to infectious diseases demands some attention and precautions.
Although humans face numerous forms of infectious diseases, nothing turns the guts more than the thought of intestinal parasites. Recently, the publicity of one cyclist's encounter with an intestinal worm led to obvious questions about how one is infected, what symptoms are present and the possible treatments.
Entry Into the Human Body
Worms belong to a class of infectious agents known as helminths. Helminths may cause disease in the gastrointestinal tract or they may enter the body and cause disease in the tissues. This column will focus on helminths that primarily live in the intestinal tract.
A person may be infected by a worm passing through the skin or by ingesting contaminated food. Intestinal worms are the largest parasites that infect humans and can range from small pinworms to large tapeworms which can grow up to 7 meters.
Some worms complete their lifecycle within the human intestine, but others require an animal vector such and a cat or dog to replicate. The three major groups of helminths are the roundworms, the tapeworms and the flukes.
The most common known intestinal worms that can pass through the skin are the roundworms, Strongyloides stercoralis, Necator americans, and Ancylostoma duodenale. The last two are also knows a "hookworms." Strongyloides is the most pathogenic of these roundworms. Its gruesome lifecycles begins as the larvae penetrate the host's skin and enter the blood stream. From there, they travel to the lungs and penetrate into the alveoli. They are literally coughed up and are then swallowed into the stomach where their lifecycle continues. They are shed into the feces and if those feces come into contact with another host, the infection enters that host and the cycle continues.
The most common intestinal helminths that enter the body through ingestion of contaminated food are the roundworm, Ascaris lumbricoides; the pinworm, Enterobious vermicularis; the whipworm Trichuris trichiura; and the infamous tapeworms, Taenia solium, Taenia saginate and Diphyllobothrium latuum.
All of these organisms enter the body through ingestion of the parasite's eggs found in contaminated feces or contaminated food. Ascaris, Enterobious and Trichuris eggs are found in the feces of infected individuals or animals. The infection is passed when those feces are inadvertently ingested, perhaps from contaminated soil.
Ascaris is the worm found in the dogs and cats. When ingested, it can invade the host body and cause severe illness. Ascaris can grow up to 30 centimeters. The tapeworms come from ingestion of eggs found in infected meat—either pork, beef or fish. Fortunately, proper cooking of the meat kills the eggs.