OVERVIEW

What are Taenia solium and Taenia saginata infections?

Taenia solium infection refers to a disease caused by the adult tapeworm residing in the human small intestine, also known as pork tapeworm infection or Taenia solium taeniasis. If the larvae of Taenia solium parasitize human subcutaneous tissues, muscles, brain, or other organs, it is called cysticercosis (neurocysticercosis)^[1].

Taenia saginata infection refers to a disease caused by the adult tapeworm residing in the human small intestine, also known as beef tapeworm infection or Taenia saginata taeniasis^[1].

Are Taenia solium and Taenia saginata infections common?

No, they are not common. However, they should not be taken lightly.

With China's socioeconomic development, improvements in agricultural production and living conditions, the transmission of parasitic diseases has been effectively controlled, with the overall national parasitic infection rate below 6%. However, in economically underdeveloped and remote rural areas, parasitic infection rates remain relatively high, exceeding 30% in some regions. In areas where raw meat consumption is a dietary habit, the infection rate of Taenia remains elevated^[2].

The "Third National Survey Report on the Current Status of Major Human Parasites" published by China's National Health Commission in 2018 showed that Taenia infections are mainly distributed in western regions such as Tibet, Sichuan, and Yunnan. The infection rates in these three provinces were 9.83%, 0.18%, and 0.12%, respectively, primarily due to the dietary habit of consuming raw beef among herders^[3].

Among the 610,000 surveyed individuals, 1,752 cases of Taenia infection were identified, with an infection rate of 0.06%. It is estimated that approximately 370,000 people nationwide are infected with Taenia. Compared to the 0.28% infection rate reported in 2005^[4], the Taenia infection rate has decreased by 99.94%^[3].

SYMPTOMS

What are the common symptoms of Taenia solium and Taenia saginata infections?

Symptoms of Taenia solium / Taenia saginata infection may include the following ^[5]:

1. Shared symptoms.
   Symptoms of adult Taenia solium and Taenia saginata infections are similar. Mild cases often show no obvious symptoms, mostly presenting as digestive issues such as abdominal pain, diarrhea, nausea, indigestion, and loss of appetite. Patients usually seek medical attention after discovering proglottids (tapeworm segments) in their stool.

2. Unique symptoms of Taenia solium infection.

Unlike Taenia saginata, Taenia solium carries the risk of self-infection with cysticercosis.

In Taenia solium infections, when intestinal peristalsis occurs or deworming medication is taken, detached gravid proglottids may reflux into the stomach, releasing oncospheres (Taenia solium larvae) and causing self-infection with cysticercosis. Symptoms of cysticercosis vary depending on the location of the cysticerci.

• Subcutaneous and muscular cysticercosis: Cysticerci nodules can be felt under the skin, with a cartilage-like hardness. Few nodules may cause no symptoms, while numerous nodules can lead to muscle soreness, swelling, numbness, or pseudohypertrophic myopathy (where muscles, especially in the limbs, appear enlarged due to multiple cysticerci nodules, but actual muscle atrophy occurs ^[6]).
• Neurocysticercosis: Presents in various forms, including epileptic, high intracranial pressure, meningoencephalitic, psychiatric, neurasthenic, or mixed types. Some cases may show no clinical manifestations or signs.
• Ocular cysticercosis: Causes visual disturbances. Fundoscopy may reveal moving scolices, and severe cases can lead to blindness.
• Cysticercosis in other locations: Symptoms depend on the affected area. Besides the above, cysticerci may also invade the oral cavity, heart, spinal cord, etc., causing different symptoms.

CAUSES

How do Taenia solium and Taenia saginata infect humans?

Human infection with Taenia solium or Taenia saginata occurs through the consumption of raw or undercooked meat containing the larval stage of these tapeworms ^[5].

• Taenia solium (Pork Tapeworm).

The adult Taenia solium resides in the human small intestine. Its gravid proglottids detach from the worm and are excreted in human feces. When these proglottids rupture, eggs are released. If pigs (intermediate hosts) ingest the eggs or proglottids, the eggs hatch in the pig's small intestine, releasing oncospheres (first-stage larvae). These larvae penetrate the intestinal wall, enter the bloodstream or lymphatic system, and migrate to various tissues, developing into cysticerci within about 10 weeks.

Pork containing cysticerci is commonly called "measly pork" or "rice-grain pork." When humans consume raw or undercooked infected pork, the cysticerci attach to the small intestine and mature into adult tapeworms within 2–3 months, after which they begin producing eggs and proglottids.

Poor hygiene, such as failing to wash hands before meals or after defecation, may also lead to accidental ingestion of tapeworm eggs from contaminated feces.

• Taenia saginata (Beef Tapeworm).

Taenia saginata has a similar life cycle to Taenia solium, except that its intermediate hosts are primarily cattle, sheep, llamas, giraffes, antelopes, and other herbivores.

DIAGNOSIS

How to Diagnose Taeniasis Solium and Taeniasis Saginata?

• Taenia solium ^[5].

  • Diagnosis of Taeniasis Solium
    A history of consuming raw or undercooked pork and the presence of expelled proglottids are of significant diagnostic value. The anal swab method or fecal sedimentation technique can be used to examine the entire stool for scolex and gravid proglottids to differentiate it from Taeniasis Saginata.

  • Diagnosis of Cysticercosis
    The examination method varies depending on the location of cysticerci.

    • Subcutaneous or superficial cysticercosis nodules can be surgically removed and biopsied.
    • Ocular cysticercosis can be examined using an ophthalmoscope.
    • Cysticerci in the brain or deep tissues can be detected using imaging techniques such as X-ray, ultrasound, CT, or MRI.
    • Immunological tests may also assist in diagnosis.

• Taenia saginata ^[3].
  Similar to Taenia solium, diagnosis is based on a history of consuming raw or undercooked beef or mutton and the presence of expelled proglottids. The anal swab method or fecal sedimentation technique can be used to examine the stool for scolex and gravid proglottids to differentiate it from Taenia solium.

TREATMENT

Can Taeniasis in Pigs and Cattle Self-Heal?

Generally, it cannot self-heal.

Parasitic infections typically induce non-sterilizing immunity in the host. This means that while the infection may trigger some immune response to prevent reinfection, it cannot completely eliminate the existing parasites ^[5]. Therefore, prompt medical treatment is still necessary.

How to Treat Taeniasis in Pigs and Cattle?

If suspicious symptoms appear after consuming raw or undercooked pork, beef, or mutton, seek medical attention immediately at the gastroenterology or infectious disease department of a hospital.

Patients are usually treated with medications such as mepacrine, praziquantel, mebendazole, or albendazole. If there is co-infection with cysticercosis (e.g., in subcutaneous tissues, muscles, eyes, or brain), additional targeted treatments may be required.

Medical treatment is strongly recommended whenever possible. Avoid self-administered deworming at home, as tapeworms are long, making it difficult to confirm complete expulsion. Moreover, infection with Taenia solium (pork tapeworm) carries the risk of cysticercosis, and deworming alone may not ensure full recovery.

DIET & LIFESTYLE

What should patients with Taenia solium and Taenia saginata pay attention to in daily life?

Develop good dietary and hygiene habits, wash hands before meals and after using the toilet, and avoid accidentally ingesting tapeworm eggs from their own feces, which may lead to repeated infections.

After deworming treatment, observe whether white tapeworm segments are excreted in the stool. If no eggs or gravid segments are found in the stool within 3–4 months, the condition can be considered cured ^[5].

PREVENTION

How to Prevent Taeniasis in Pigs and Cattle?

Prevention of taeniasis in pigs and cattle can be achieved through the following measures ^[5]:

Mass Screening and Prevention: In high-risk areas, conduct mass screenings and treatments to prevent cross-infection among the population.

Manage Pig Pens and Toilets: Educate the public on proper toilet management and safe disposal of feces. Keep pigs in pens to prevent mutual infection between humans and livestock.

Strengthen Meat Inspection: Ensure strict inspection and processing of meat before it reaches the market.

Separate Raw and Cooked Food: Store, handle, and use separate utensils for raw and cooked food during preparation.

Freeze Meat Before Cooking: Store pork/beef at freezing temperatures for sufficient time to kill potential cysticerci. Specifically:

• Pork should be frozen at -13°C to -12°C for 12 hours to ensure all cysticerci are killed ^[6].
• Beef should be kept at -23°C to -22°C for 10 days to guarantee the elimination of cysticerci ^[8].

During cooking, ensure the internal temperature of pork and beef reaches at least 70°C to kill any cysticerci ^[7]. Avoid consuming raw or undercooked pork and beef.

Maintain Good Hygiene: Practice personal and food hygiene, including washing hands before meals and after using the toilet.