The very thought of being infected with a parasite is a pretty gross and disturbing idea: a living entity, roaming around inside of you, feeding off of you. Yet this nightmarish scenario is a reality for many people (and animals) around the world. As an example of the prevalence, a recent study in a province of Thailand determined that approximately 16% of the population had some form of a parasitic infection.
But these kinds of parasitic infections aren’t just isolated to developing countries and parts of the world where food safety doesn’t have as great a focus. Even as a ‘first world’ country with more advanced agricultural processes and food safety regimes, the United States is not immune to parasites. Indeed, the Centers for Disease Control and Prevention (CDC) has identified several “neglected parasitic infections” (NPIs) that likely affect tens of millions of Americans.
However, not all parasites are created equal. While scientists are unable to determine the precise number of parasites that exist in the world, some have estimated that potentially 40% of known species on the planet are parasites that parasitize the other 60% of species. Defined most broadly as any organism that has adapted to living on or in another organism, this estimate includes organisms like fungi, protozoa, viruses, and bacteria.
Of course, such microscopic organisms don’t quite have the “ick factor” of their parasitic brethren: helminths. Helminth is a term used for the group of macroparasitic worms that primarily live in the digestive tracts of vertebrate hosts. The National Institutes of Health estimates that there may be up to 300,000 different species of helminth. Perhaps the most “famous” helminth, though, is the common tapeworm.
What is a Tapeworm?
As discussed above, a tapeworm is a type of parasite that lives and feeds in the digestive tract of its host. The word “tapeworm” is a common term for Eucestoda, a subclass of flatworms in the taxonomic class called Cestoda; the other subclass is called Cestodaria. The primary difference between these two can be identified in the larvae: Eucestoda has six posterior hooks on the scolex (the tapeworm head) and Cestodaria has ten hooks.
Of the many thousands of species of helminth, there are only a few cestodes that typically affect humans. Some of these are categorized by the foods where they are found: Diphyllobothrium latum (fish tapeworm), Taenia solium (pork tapeworm), and Taenia saginata (beef tapeworm). Some other common tapeworms are hymenolepis (typically in rodents) and Dipylidium caninum (typically in dogs).
So how does one become a tapeworm infection? As is perhaps implied by the categorization scheme noted above, humans most often become infected by eating undercooked meat and fish. When a cow or pig has a tapeworm infestation, for example, the worms lay eggs inside the animal. These tapeworm eggs (or resulting larvae) can then get lodged in the muscle tissue of the animal. These eggs can continue to live in the tissue of the animal even after slaughter. Then, if the meat isn’t prepared properly, the parasite can be passed to a human when the undercooked meat is ingested. The tapeworm larvae then develop into fully grown adult tapeworms.
Another potential cause of a tapeworm infection is another human. Since the tapeworm lives in the digestive tract, its eggs can also be passed in the stool. If an infected person who prepares food doesn’t wash their hands properly after using the bathroom, the food can become contaminated and also be passed on to a new host.
Many developing countries have poor water treatment facilities and processes. As a result, it is easy for contaminated drinking water to affect large population areas. Sometimes feces from an infected animal enters the soil and is able to then move to water sources; in such circumstances, a wide variety of different parasites could potentially infect the humans who rely on that water.
What are the Symptoms of a Tapeworm Infection?
Unfortunately, a lot of people who get infected by a tapeworm may not even have any symptoms and therefore may be oblivious to their infection for years. For people who never experience any symptoms, the only indicator that they were ever infected is seeing the tapeworm in a stool sample; imagine looking down at your poop and seeing a wriggly worm!
However, there are some common symptoms that do tend to show up, especially in the more common intestinal infections such as taeniasis (from eating infected beef or pork):
- Loss of appetite
- Weight loss
- Reduced absorption of food nutrients
- Weakness or fatigue
- Abdominal pain
- Strong desire for salty foods
In some rare cases, the eggs laid by the tapeworm can develop into larvae and become mobile. When this happens, the larvae can migrate out of the digestive tract to other parts of the body. One of the most dangerous scenarios is when the larvae become embedded elsewhere and form a cyst. This condition is called cysticercosis and can affect the muscles, eyes, skin, or other organs, usually resulting in damage to the tissue where they form.
In very rare cases, these cysts can form in the brain itself. This condition, known as neurocysticercosis, can be identified by headaches or a variety of other neurological conditions like seizures. This condition can also become life-threatening.
Treatment for Tapeworms
There are a variety of treatments available for tapeworm infections, depending on the severity of the condition and whether or not the larvae have migrated out of the digestive tract. Your doctor may request a stool sample to look for signs of the tapeworm or a blood test if no signs are present.
Since the majority of tapeworm cases are mild and non-life-threatening, your doctor will typically prescribe an oral medication to deal with the problem. One of the most common medications is praziquantel, a substance that essentially paralyzes the tapeworm inside your gut. When exposed to the medication, the tapeworm releases itself from the intestinal wall and is eventually passed in a bowel movement. This course of medication typically takes 1-3 months to be fully resolved and is effective in 95% of patients.
For those rare cases of cysticercosis, anti-inflammatory medication may be prescribed in order to reduce swelling that the presence of the cysts has caused in different tissues in the body. This may be combined with anthelmintic drugs used to shrink the cysts. Surgery is also an option in organs where the cysts may do permanent damage.
In situations where patients have developed neurocysticercosis, more drastic measures may be necessary. Depending on where the cyst is located, surgery is an option to remove it. In some cases, a shunt might be used to drain excess fluid from a cyst that wouldn’t otherwise be safe to remove.
When do I see a doctor?
You may be wondering: how do I know when to see a doctor about this? If you’re like most people who have the tapeworm, you may very well never be aware of it; and it might even resolve itself over time. But for those who have been experiencing some of the symptoms discussed here, it’s wise to consult a doctor any time you have changes in your bowel habits or a variety of these symptoms that last longer than a few days.
You should especially be wary if you have any of the digestive symptoms AND either a mysterious lump on your skin or headaches or other signs of a neurological problem. This combination of symptoms may indicate invasive infection and cysticercosis, problems that, while rare, should be addressed as soon as possible. In fact, your staff is regularly trying to educate your patients to be aware of changes in your daily GI habits. If changes come and go in a day or two that is not a matter of concern; but if changes linger, or worsen, it’s time to make an appointment.
If you notice chronic changes in your bowel habits, request an appointment with Cary Gastro today. Our highly trained staff will be able to diagnose and treat any gastrointestinal issues you might be facing.