Ever heard someone say, "He's so skinny he must have a tapeworm"? Tapeworms may seem like a joke to some people, but they can be a real problem in some parts of the world. In fact, a worm that can grow to more than 82 feet long, live in the intestines, and eat your digested food probably seems more horror movie than comedy.
Here's what you need to know about tapeworms and how to keep yourself from getting one.
What Is a Tapeworm?
Tapeworms are flat worms that live in a person's digestive tract. They can grow to more than 82 feet (30 meters) and live as long as 30 years.
Tapeworms are parasites. As you probably know from biology class, parasites are organisms that live in, or on, other organisms (called "hosts"). Parasites take their nutrients from the host, sometimes depriving the host of nutrition.
Tapeworms get into the body when a person eats or drinks something that's infected with a worm or its eggs. Once inside the body, the tapeworm head attaches to the inner wall of the intestines. The tapeworm feeds off the food that the host is digesting. It uses this nutrition to grow.
Tapeworms are made up of segments, and they get longer by growing new segments. Each segment can reproduce by making thousands of eggs. Since tapeworms can have more than 3,000 segments, that's a lot of opportunity to spread.
New segments grow at the head of the tapeworm, pushing older segments to the end of the line, where they break off. These segments, along with the eggs they contain, pass out of the digestive tract in the host's feces (poop). If the infected feces aren't disposed of in a sanitary way — like down a flush toilet — they can get into the soil or water.
Tapeworm segments can live for months in the environment, waiting for a host to come along. Animals like cows or pigs that eat grass or nose around in the soil can pick up tapeworm segments or eggs. When the tapeworm reaches the animal's intestine, the attach-and-grow cycle begins again.
If all of that sounds pretty scary (not to mention disgusting), there is some good news: Most tapeworm infections are easy to treat.
How Do Tapeworms Infect People?
As if tapeworms aren't gross enough on their own, the ways people get them really amps up the ick factor:
- Tapeworms can spread when someone eats or drinks food or water that's contaminated with infected feces. This is one reason why tapeworm infections are rare in places that have good sanitation. Flush toilets, sewer systems, and water treatment plants help keep feces out of the water and food supply.
- People can pass tapeworm eggs to others when they don't wash their hands after using the bathroom. Tapeworm eggs in feces can easily spread into food or onto surfaces like doorknobs.
- People can get tapeworms from eating meat or fish that hasn't been cooked enough to kill the tapeworm or its eggs.
What Are the Signs of a Tapeworm?
Most people with tapeworms don't feel anything. It can take months or years to notice any signs of a tapeworm. They can include:
- mild nausea
- abdominal pain
- loss of appetite
- weight loss
Sometimes, a person can feel a piece of the worm coming out through the anus or see it in their feces.
There are different types of tapeworm. One (fish tapeworm) can cause anemia because it absorbs vitamin B12, which helps make red blood cells. This can lead someone to feel tired, short of breath, or notice other signs of anemia. In severe cases of B12 deficiency, a person can have numbness or other problems with their nervous system. Getting rid of the tapeworm usually makes vitamin B12 levels normal again.
The eggs of another type of tapeworm (pork tapeworm) can hatch into larvae in the intestine. These larvae go through the intestinal wall and enter the bloodstream. From there they can travel to different organs in the body, such as muscles, eyes, or brain, where they form cysts. This disease is known as cysticercosis. It is rare in the United States, but common in many developing countries.
With cysticercosis, a person might develop lumps under the skin. If the cysts are in the brain, someone might have seizures. Cysts in the eyes can cause vision problems; cysts in the heart can lead to an abnormal heartbeat; and cysts in the spine might cause weakness or trouble walking.
You can't get cysticercosis from eating pork. Eating contaminated pork can give someone a tapeworm in the intestines, but it won't turn into cysticercosis. In order to develop cysticercosis, people have to swallow the eggs of the pork tapeworm, and these eggs aren't found in the meat itself. They are found in feces and around the anus.
Cysticercosis happens when someone eats food that has been contaminated with feces. It can be any kind of food — all it takes is for that food to come into contact with feces. So, for example, if a person who has a tapeworm prepares a meal and doesn't wash his or her hands properly after using the bathroom, that person's feces can end up in the food.
When Should You Call a Doctor?
Tell a parent or call a doctor if you see worms in your feces or if you have abdominal pain or other symptoms that might suggest a tapeworm infection. You'll also want to call a doctor if you're showing signs of infection after traveling to a part of the world that doesn't have good sanitation.
People with masses or lumps under the skin who develop a fever, headache, or any of the symptoms of cysticercosis need to call a doctor right away. If someone has seizures or trouble moving, walking, or talking, it's time for a trip to the emergency room.
What Do Doctors Do?
To diagnose a tapeworm infection, doctors usually examine a stool sample for tapeworm segments. Doctors may need to get a couple of samples because tapeworms don't always show up in every sample.
Doctors can easily cure a tapeworm infection with prescription anti-parasite drugs. Often, just one dose is enough.
Tapeworm infection isn't usually serious. Most people have no complications. But in a few rare cases, large tapeworms can block up a person's intestines, appendix, bile duct, or pancreatic duct. This can lead to things like appendicitis or inflamed gallbladder. They're no fun, but they can be treated.
Cysticercosis is a much more serious condition. If the doctor thinks you may have this condition, he or she might order a CT scan (also called CAT scan) or magnetic resonance imaging (MRI) of the brain to look for cysts. In some cases, anti-parasite drugs can help shrink cysts and keep them from causing problems. Doctors may also prescribe anti-inflammatory drugs (like steroids) for cysticercosis infections. If someone has seizures, doctors may give that person anti-epilepsy medications.
If someone gets hydrocephalus because of cysticercosis, doctors may put a shunt, or tube, in the head to drain excess fluid. Surgeons will remove cysts if they pose a threat to the eyes, liver, lungs, heart, or other organs.
Can I Prevent Tapeworm Infection?
You can protect yourself by always following these tips:
- Wash your hands well and often with soap and warm water, especially after using the bathroom and before touching food. If you ever need a reminder to wash your hands carefully, this may be it: Tapeworm eggs can be found near the anus. If you don't wash after wiping, you could end up eating your snack or meal with a side of tapeworm eggs.
- Thoroughly cook meat until juices run clear and the centers are no longer pink.
- Cook fish until it is solid in color (no longer clear) and flakes when separated with a fork.
- Freeze meat for 24 hours before cooking to kill tapeworm eggs.
Here are some things you should do if you're in a place where tapeworm infections are common:
- Wash and cook all fruits and vegetables with safe water.
- Avoid raw or undercooked meat and fish, raw fruits, and vegetables that you aren't able to peel yourself and any food from street vendors.
- Drink only water boiled for a least a minute, bottled water (carbonated is more reliable than regular), or other beverages in bottles and cans. Wipe the top of cans and bottles before you drink from them or use a straw. Avoid fountain drinks and ice cubes.
Most tapeworm infections are harmless. But it's always a good idea to get checked out by a doctor if you have symptoms.
Reviewed by: Rupal Christine Gupta, MD
Date reviewed: October 2014