Tapeworm infection, pork: Known medically as cysticercosis, an infection caused by Taenia solium (the pork tapeworm). Infection occurs when the tapeworm larvae enter the body and form cysticerci (SIS-tuh-sir-KEY) (cysts). When cysticerci are found in the brain, the condition is called neurocysticercosis (NEW-row SIS-tuh-sir-KO-sis).
The tapeworm that causes cysticercosis is found worldwide. Infection is found most often in rural, developing countries with poor hygiene where pigs are allowed to roam freely and eat human feces. This allows the tapeworm infection to be completed and the cycle to continue. Infection can occur, though rarely, if you have never traveled outside of the United States. Taeniasis and cysticercosis are very rare in Muslim countries where eating pork is forbidden.
Cysticercosis is contracted by accidentally swallowing pork tapeworm eggs. Tapeworm eggs are passed in the bowel movement of a person who is infected. These tapeworm eggs are spread through food, water, or surfaces contaminated with feces. This can happen by drinking contaminated water or food, or by putting contaminated fingers to your mouth. A person who has a tapeworm infection can reinfect themselves (autoinfection). Once inside the stomach, the tapeworm egg hatches, penetrates the intestine, travels through the bloodstream and may develop into cysticerci in the muscles, brain, or eyes.
The signs and symptoms of the disease depend on the location and number of cysticerci in the body.
- Cysticerci in the muscles: Cysticerci in the muscles generally do not cause symptoms. However, you may be able to feel lumps under your skin.
- Cysticerci in the eyes: Although rare, cysticerci may float in the eye and cause blurry or disturbed vision. Infection in the eyes may cause swelling or detachment of the retina.
- Cysticerci in the brain or spinal cord (neurocysticercosis): Symptoms of neurocysticercosis depend upon where and how many cysticerci (often called lesions) are found in the brain. Seizures, and headaches are the most common symptoms. However, confusion, lack of attention to people and surroundings, difficulty with balance, swelling of the brain (called hydrocephalus) may also occur. Death can occur suddenly with heavy infections.
Symptoms can occur months to years after infection, usually when the cysts are in the process of dying. When this happens, the brain can swell. The pressure caused by swelling is what causes most of the symptoms of neurocysticercosis. Most people with cysticerci in muscles won’t have symptoms of infection.
Diagnosis can be difficult and may require several testing methods. The health care provider will usually ask about where the patient has traveled and their eating habits. Diagnosis of neurocysticercosis is usually made by MRI or CT brain scans. Blood tests are available to help diagnose an infection, but may not always be accurate. If surgery is necessary, confirmation of the diagnosis can be made by the laboratory.
Treatment is generally with anti-parasitic drugs in combination with anti-inflammatory drugs. Surgery is sometimes necessary to treat cases in the eyes, cases that are not responsive to drug treatment, or to reduce brain edema (swelling). Not all cases of cysticercosis are treated. Often, the decision of whether or not to treat neurocysticercosis is based upon the number of lesions found in the brain and the symptoms. When only one lesion is found, often treatment is not given. If there is more than one lesion, specific anti-parasitic treatment is generally recommended.
If the brain lesion is considered calcified (this means that a hard shell has formed around the tapeworm larvae), the cysticerci is considered dead and specific anti-parasitic treatment is not beneficial.
As the cysticerci die, the lesion will shrink. The swelling will go down, and often symptoms (such as seizures) will go away.
To prevent cysticercosis and other disease causing germs:
- Avoid eating raw or undercooked pork and other meats.
- Don’t eat meat of pigs that are likely to be infected with the tapeworm.
- Wash hands with soap and water after using the toilet and before handling food, especially when traveling in developing countries.
- Wash and peel all raw vegetables and fruits before eating. Avoid food that may be contaminated with feces.
- Drink only bottled or boiled (1 minute) water or carbonated (bubbly) drinks in cans or bottles. Do not drink fountain drinks or any drinks with ice cubes. Another way to make water safe is by filtering it through an “absolute 1 micron or less” filter AND dissolving iodine tablets in the filtered water. “Absolute 1 micron” filters can be found in camping/outdoor supply stores.
Cysticercosis is not spread from person to person. However, a person infected with the intestinal tapeworm stage of the infection (T. solium) will shed tapeworm eggs in their bowel movements. Tapeworm eggs that are accidentally swallowed by another person can cause infection.
Anyone suspected of having cysticercosis (and family members) should be tested. Because the tapeworm infection can be difficult to diagnose, several stool specimens over several days may be needed to examine the stools for evidence of a tapeworm.