TAENIA SOLIUM SAGINATA

Taeniasis in humans is a parasitic infection caused by the tapeworm species Taenia saginata (beef tapeworm), Taenia solium (pork tapeworm), and Taenia asiatica (Asian tapeworm). Humans can become infected with these tapeworms by eating raw or undercooked beef (T. saginata) or pork (T. solium and T. asiatica). People with taeniasis may not know they have a tapeworm infection because symptoms are usually mild or nonexistent.

Taenia solium tapeworm infections can lead to, which is a disease that can cause seizures, so it is important seek treatment.

FAQS

What is taeniasis?

T. solium tapeworm infections can lead to cysticercosis, which is a disease that can cause seizures, so it is important seek treatment.

Where does taeniasis occur?

Taenia saginata and T. solium are found worldwide. Infections with T. saginata occur wherever contaminated raw beef is eaten, particularly in Eastern Europe, Russia, eastern Africa and Latin America. Taeniasis due to T. saginata is rare in the United States, except in places where cattle and people are concentrated and sanitation is poor, such as around feed lots where cattle can be exposed to human feces. Tapeworm infections due to T. solium are more prevalent in under-developed communities with poor sanitation and where people eat raw or undercooked pork. Higher rates of illness have been seen in people in Latin America, Eastern Europe, sub-Saharan Africa, India, and Asia. Taenia solium taeniasis is seen in the United States, typically among Latin American immigrants. Taenia asiatica is limited to Asia and is seen mostly in the Republic of Korea, China, Taiwan, Indonesia, and Thailand.

What are the signs and symptoms of taeniasis?

Most people with tapeworm infections have no symptoms or mild symptoms. Patients with T. saginata taeniasis often experience more symptoms that those with T. solium or T. asiatica infections because the T. saginata tapeworm is larger in size (up to 10 meters (m)) than the other two tapeworms (usually 3 m). Tapeworms can cause digestive problems including abdominal pain, loss of appetite, weight loss, and upset stomach. The most visible sign of taeniasis is the active passing of proglottids (tapeworm segments) through the anus and in the feces. In rare cases, tapeworm segments become lodged in the appendix, or the bile and pancreatic ducts.

Infection with T. solium tapeworms can result in human cysticercosis, which can be a very serious disease that can cause seizures and muscle or eye damage.

Taenia saginata does not cause cysticercosis in humans. It is not clear if T. asiatica causes cysticercosis in humans or not.

Is taeniasis common?

Taeniasis is under-reported in a significant portion of the world because diagnosis is difficult in resource-poor settings. The number of new cases in the U.S. each year is probably less than 1000, but an exact number is not known.

What should I do if I think I have taeniasis?

Contact your health care provider for proper diagnosis and care.

Is medication available to treat taeniasis?

Yes. Praziquantel is the drug of choice. Niclosamide is an alternative drug. See your health care provider for proper diagnosis and care.

How did I get taeniasis?

Eating raw or undercooked contaminated beef or pork is the primary risk factor for acquiring taeniasis. Because of this, certain groups with dietary restrictions for these meats may have a lower risk of taeniasis.

How can I prevent infection with taeniasis?

One way to prevent taeniasis is to cook meat to safe temperatures. A food thermometer should be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked. USDA recommends the following for meat preparation.

For Whole Cuts of Meat (excluding poultry)

Cook to at least 145° F (63° C) as measured with a food thermometer placed in the thickest part of the meat, then allow the meat to rest* for three minutes before carving or consuming.
According to USDA, "A 'rest time' is the amount of time the product remains at the final temperature, after it has been removed from a grill, oven, or other heat source. During the three minutes after meat is removed from the heat source, its temperature remains constant or continues to rise, which destroys pathogens."

Should I be concerned about spreading taeniasis to the rest of my household?

No. However, a disease called cysticercosis can occur when T. solium tapeworm eggs are ingested. For example, people with poor hygiene who have taeniasis -- with or without symptoms -- will shed tapeworm eggs in their feces and might accidentally contaminate their environment. This can lead to transmission of cysticercosis to themselves or others unknowingly.

Can I get taeniasis from my dog or cat that was diagnosed with tapeworm infection?

In general, no. The tapeworm that your pet was diagnosed with is more than likely the flea tapeworm (Dipylidium caninum). Dog or cat tapeworm infections are a result of your pet swallowing a parasite-contaminated flea. Only in very rare instances do humans accidentally swallow the contaminated fleas.

EPIDEMIOLOGY & RISK FACTORS

The tapeworms that cause taeniasis (Taenia saginata, T. solium, and T. asiatica) are found worldwide. Eating raw or undercooked beef or pork is the primary risk factor for acquiring taeniasis. Persons who don't eat raw or undercooked beef or pork are not likely to get taeniasis.

Infections with T. saginata occur wherever contaminated raw beef is eaten, particularly in Eastern Europe, Russia, eastern Africa and Latin America. Taeniasis due to T. saginata is rare in the United States, except in places where cattle and people are concentrated and sanitation is poor, such as around feed lots when cattle can be exposed to human feces. Tapeworm infections due to T. solium are more prevalent in under-developed communities with poor sanitation and where people eat raw or undercooked pork. Higher rates of illness have been seen in people in Latin America, Eastern Europe, sub-Saharan Africa, India, and Asia. Taenia solium taeniasis is seen in the United States, typically among Latin American immigrants. Taenia asiatica is limited to Asia and is seen mostly in the Republic of Korea, China, Taiwan, Indonesia, and Thailand.

A disease called cysticercosis can occur when T. solium tapeworm eggs are ingested. For example, people with poor hygiene who have taeniasis -- with or without symptoms -- will shed tapeworm eggs in their feces and might accidentally contaminate their environment. This can lead to transmission of cysticercosis to themselves or others.

BIOLOGY

Causal Agent:

The cestodes (tapeworms) Taenia saginata (beef tapeworm) and T. solium (pork tapeworm). Taenia solium eggs can also cause cysticercosis.

Life Cycle:

Life Cycle of Taenia saginata and Taenia solium

Taeniasis is the infection of humans with the adult tapeworm of Taenia saginata or Taenia solium. Humans are the only definitive hosts for T. saginata and T. solium. Eggs or gravid proglottids are passed with feces; the eggs can survive for days to months in the environment. Cattle (T. saginata) and pigs (T. solium) become infected by ingesting vegetation contaminated with eggs or gravid proglottids. In the animal's intestine, the oncospheres hatch, invade the intestinal wall, and migrate to the striated muscles, where they develop into cysticerci. A cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat. In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for years. The adult tapeworms attach to the small intestine by their scolex and reside in the small intestine. Length of adult worms is usually 5 m or less for T. saginata (however it may reach up to 25 m) and 2 to 7 m for T. solium. The adults produce proglottids which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool (approximately 6 per day). T. saginata adults usually have 1,000 to 2,000 proglottids, while T. solium adults have an average of 1,000 proglottids. The eggs contained in the gravid proglottids are released after the proglottids are passed with the feces. T. saginata may produce up to 100,000 and T. solium may produce 50,000 eggs per proglottid respectively.

Life cycle image and information courtesy of DPDx.

DISEASE

Human taeniasis is a parasitic infection caused by three tapeworm species, T. saginata (known as the beef tapeworm), T. solium (pork tapeworm), and T. asiatica (the Asian tapeworm). Humans are the only hosts for these Taenia tapeworms. Humans pass the tapeworm segments and/or eggs in feces and contaminate the soil in areas where sanitation is poor. Taenia eggs can survive in a moist environment and remain infective for days to months. Cows and pigs become infected after feeding in areas that are contaminated with Taenia eggs from human feces. Once inside the cow or pig, the Taenia eggs hatch in the animal’s intestine and migrate to striated muscle to develop into cysticerci, causing a disease known as cysticercosis. Cysticerci can survive for several years in animal muscle. Humans become infected with tapeworms when they eat raw or undercooked beef or pork containing infective cysticerci. Once inside humans, Taenia cysticerci migrate to the small intestine and mature to adult tapeworms, which produce segments and eggs that are passed in feces.

Symptoms

Most people with tapeworm infections have no symptoms or mild symptoms. Patients with T. saginata taeniasis often experience more symptoms that those with T. solium because the T. saginata tapeworm is larger in size (up to 10 meters (m)) than T. solium (usually 3 m). Tapeworms can cause digestive problems including abdominal pain, loss of appetite, weight loss, and upset stomach. The most visible symptom of taeniasis is the active passing of proglottids (tapeworm segments) through the anus and in the feces. In rare cases, tapeworm segments become lodged in the appendix, or the bile and pancreatic ducts.

Infection with T. solium tapeworms can result in human cysticercosis, which can be a very serious disease that can cause seizures and muscle or eye damage.

Taenia saginata does not cause cysticercosis in humans. It is not clear if T. asiatica causes cysticercosis in humans or not.

DIAGNOSIS

Diagnosis of Taenia tapeworm infections is made by examination of stool samples; individuals should also be asked if they have passed tapeworm segments. Stool specimens should be collected on three different days and examined in the lab for Taenia eggs using a microscope. Tapeworm eggs can be detected in the stool 2 to 3 months after the tapeworm infection is established.

Tapeworm eggs of T. solium can also infect humans, causing cysticercosis. It is important to diagnose and treat all tapeworm infections.

PREVENTION AND CONTROL

One way to prevent taeniasis is to cook meat to safe temperatures. A food thermometershould be used to measure the internal temperature of cooked meat. Do not sample meat until it is cooked. USDA recommends the following for meat preparation.