Tapeworm Infection: Signs, Symptoms, and Complications

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In most cases, tapeworm infections won’t cause any noticeable signs or symptoms, but in others they can cause diarrhea, abdominal pain, nausea, and weight loss. Symptoms also vary by the type of tapeworm you are infected with. Several types of tapeworms can infect humans, including the beef tapeworm (Taenia saginata), pork tapeworm (Taenia solium), Asian tapeworm (Taenia asiatica), dwarf tapeworm (Hymenolepis nana), and Diphyllobothrium latum, which is a broad tapeworm that infects fish.

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Frequent Symptoms

Your symptoms may vary epending on the type of tapeworm you're infected with.

Asian tapeworm (T asiatica), Beef Tapeworm (T saginata), Pork Tapeworm (T solium)

Humans infected with one of the different species of tapeworms in the Taenia family (which is called taeniasis) may experience no signs or symptoms, or only mild symptoms. The beef tapeworm (T saginata) is the largest of these parasites (it can grow to over 30 feet long) and so symptoms might be more noticeable when infected with this type. 

Symptoms of taeniasis may include:

  • abdominal pain
  • lack of appetite 
  • passing tapeworm parts in stool
  • weight loss
  • upset stomach

Dwarf Tapeworm (H nana)

Most infections with the dwarf tapeworm won’t cause symptoms but when they do occur, there can be:

  • abdominal pain
  • diarrhea
  • loss of appetite
  • nausea
  • weakness

Children who are infected may also experience: 

  • anal itching
  • headache
  • sleep disturbances

Fish or Broad Tapeworm (D latum)

Most symptoms are mild, but can include: 

  • abdominal pain
  • diarrhea
  • fatigue
  • loss of appetite
  • weakness
  • weight loss

Complications

Complications from tapeworm infections may occur from either tapeworm sections or eggs migrating inside or outside the digestive tract (depending on the species of the worm).

For a tapeworm infection, the adult tapeworm living in the digestive tract produces segments which contain both female and male reproductive parts. These segments, called proglottids, become pregnant with eggs, are released from the parent tapeworm, and can pass into other areas of the digestive system or out of the body with a bowel movement.

Asian tapeworm (T asiatica), Beef Tapeworm (T saginata), Pork Tapeworm (T solium)

It is rare, but when the proglottids migrate through the digestive tract and to other organs, they can block bile ducts or pancreatic ducts, or get into the appendix. Symptoms of a blocked bile duct can include:

  • middle abdomen pain
  • nausea
  • severe, increasing upper abdominal pain lasting 30 minutes to hours
  • pain between the shoulder blades 
  • pain under the right shoulder
  • vomiting

Fish or Broad Tapeworm (D latum)

The broad tapeworm siphons vitamin B12 from its host. Because vitamin B12 is necessary for the creation of blood cells, the result can be both low vitamin B12 and anemia. Vitamin B12 deficiency can cause neuropathy, which can be life-threatening if untreated. Symptoms of these complications can include:

  • Depression
  • Dizziness
  • Fatigue
  • Headaches
  • Low energy
  • Rapid heart beat
  • Ringing in the ears

The fish tapeworm can grow to be quite large, reaching as long as 30 feet. Because of this large size, complications can include bowel (intestinal) obstructions and gallbladder problems. These complications can occur when the tapeworm produces proglottids, which migrate to the different structures inside the digestive tract.

Pork Tapeworm (T solium)

The eggs of the pork tapeworm can cause a serious complication called cysticercosis. A person infected with the pork tapeworm passes eggs in their stool. After going to the bathroom, eggs may get on the infected person’s hands and then be transmitted to food, water, or to surfaces. A person eating or drinking something with eggs on it may also become infected.

What’s different about the pork tapeworm eggs is that when they hatch and grow into the larval stage, they can leave the intestinal tract and go into other areas of the body, causing cysts. Cysts may occur in the muscles, eyes, brain, under the skin, or other organs.

When cysts form in the central nervous system, such as in the brain or the spinal cord, it causes a complication called neurocysticercosis. This condition may result in seizures and other neurological symptoms. While rare in the United States, this is a major public health concern in developing nations where tapeworm infection is more common.

The symptoms caused by neurocysticercosis will depend on the location of the cysts, but can include:

  • headaches
  • seizures 
  • numbness
  • tingling
  • weakness 

When to See a Doctor

Symptoms are often mild, which might not prompt a visit to the doctor right away. However, symptoms in the digestive tract such as ongoing diarrhea, nausea, abdominal pain, and unintended weight loss are reasons to see a physician. Tapeworm segments might be visible in the stool, and if that’s the case, collecting the stool and placing it in a plastic container to bring to a doctor or a lab as soon as possible can help in getting a diagnosis.

Red flag symptoms such as severe abdominal pain, vomiting, or diarrhea and/or lack of bowel movements and abdominal distention could indicate a blockage and are a reason to seek medical care immediately. Seizures and tingling, numbness, or weakness in the extremities are also a reason to see a doctor right away, and possibly go to emergency if symptoms are severe.

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Article Sources
  • Centers for Disease Control and Prevention. "Hymenolepiasis FAQs.” Global Health – Division of Parasitic Diseases. 10 Jan 2012.
  • Pearson R. "Diphyllobothriasis (Fish Tapeworm Infection).” Merck Manual Professional Edition. Aug 2016.
  • Pearson R. "Taenia Solium (Pork Tapeworm) Infection and Cysticercosis.” Merck Manual Professional Edition. Aug 2016.