Teniosis: what is it, causative agent, symptoms, treatment, prevention

What is teniasis?

Teniosis or Teniodosis Is an intestinal infection caused by tapeworms. The infection is asymptomatic in most cases, although it sometimes presents with gastrointestinal symptoms (abdominal discomfort, diarrhea, weight loss). Teniosis is common throughout the world, and is more common in countries with less hygienic development.

Causes of teniasis

Intestinal teniosis occurs mainly after eating raw or undercooked food pork, beef or freshwater fish or, in the case of dwarf tapeworm infestation, contaminated food or water.

Several types of tapeworms can cause infection in humans. The causative agents of teniasis include:

• Taenia saginata (bovine tapeworm);
• Taenia solium (pork tapeworm);
• Taenia asiatica, Infected by eating pork in Asia (Asian tapeworm)
• Diphyllobothrium latum (wide tape);
• Hymenolepis nana (dwarf tapeworm).

Adult tapeworms of other species - Echinococcus granulosus and

Echinococcus multilocularis (dog tapeworms) - live in the intestines of dogs and other members of the canine family. These parasites sometimes infect humans by forming cysts in the liver or other organs.

Tapeworms are made up of three main parts:

• the head with which they attach to the intestine;
• neck that can regenerate;
• the rest of the worm, which consists of many segments (called proglottids) and may contain eggs.

If the head and neck are not destroyed during treatment, the entire worm can recover.

- Life cycle of pork tapeworm, bovine tapeworm and broad tapeworm.

Pork tapeworm, bovine tapeworm and broad tapeworm are large, flat, tape-like worms that live in the human intestine and grow up to 4.5-9 meters in length. (A person is considered the final owner, since tapeworms live in his intestines.) Egg-bearing worm fragments (proglottids) are excreted with feces.

If untreated human excreta is thrown directly into the environment, eggs may be absorbed by their intermediates. hosts - pigs, cattle or (in the case of a wide tapeworm) small freshwater crustaceans, which in turn are eaten fish. In intermediate hosts, larvae hatch from eggs. The larvae invade the intestinal wall and travel through the bloodstream to skeletal muscle and other tissues, where they form cysts.

A person becomes infected with the parasite by eating cysts in raw or undercooked meat or some types of freshwater fish. Cysts emerge from the membrane and develop into adult worms, which attach to the intestinal wall. The worms then begin to grow in length and lay eggs.

- The life cycle of the dwarf tapeworm.

The dwarf tapeworm is small - only about 40 millimeters. Human infection occurs when eggs enter the body, and not cysts, as in the case of infection with pork and bovine tapeworms. Eggs can enter food or water from contaminated human feces, or can enter the body through the mouth through contact with contaminated people. Sometimes a person can accidentally swallow infected insects - fleas and bugs contained in grain.

The eggs turn into adults living in the intestines. Adult tapeworms lay eggs, which are excreted in the feces. These eggs can enter the body of another or the same person, resulting in the development of a new generation of adult worms.

Sometimes eggs hatch in the intestines and develop into adult dwarf tapeworms, infecting the body without leaving it. This type of infection is called autoinfection (self-infection). Large numbers of dwarf tapeworms can accumulate and cause symptoms.

- Cysticercosis.

A person who has swallowed the eggs of a pork tapeworm can be an intermediate host for this tapeworm (but a person cannot be an intermediate host for a bovine tapeworm and other tapeworms). A person can become an intermediate host under certain conditions described below:

• When swallowing pork tapeworm eggs with food or water contaminated with human feces.
• When placing eggs in the mouth after contact with an infected person or contaminated items of clothing or furniture.
• If an adult worm lives in the intestines, then a person can re-infect himself with eggs that come out with feces (for example, when eating contaminated food or water), or if egg-containing worm segments (proglottids) enter the stomach from the intestine, where eggs are released (autoinfection).

As in the case of animals in the role of intermediate hosts, when they enter the intestine, the eggs turn into spheres that contain larvae (the so-called oncospheres). The spheres invade the intestinal wall and move to the brain, muscles, other organs or tissues under the skin, where they begin to form cysts. In humans, this form of the disease is called cysticercosis.

Symptoms of teniasis

Although adult tapeworms cause little or no symptoms in the intestines, they sometimes lead to abdominal discomfort, diarrhea, and other symptoms. In some cases, people infected with the tapeworm may feel part of the tapeworm coming out of the anus, or see part of the tapeworm in the stool. Dwarf tapeworm, unlike other types of tapeworms, is more likely to cause abdominal symptoms, such as:

• nausea;
• vomit;
• diarrhea;
• abdominal discomfort;
• loss of appetite and weight.

Wide tapeworm can lead to anemiabecause it absorbs vitamin B12, which is essential for the production of red blood cells.

Cysticercosis symptoms are caused by cysts that form in the brain and other organs (spinal cord, liver, lungs, and eyes). These cysts can cause severe, sometimes life-threatening symptoms many years after the initial infection, when they begin to break down and cause inflammation.

Cysts in the brain and tissues covering the brain (meninges) can lead to headaches in patients with cysticercosis, epilepsy, disorientation, and other neurological symptoms. Rarely, cysts develop in the eyeball, sometimes causing blindness, or in the spinal cord, leading to muscle weakness and paralysis.

Diagnostics

• With teniasis, examination of a stool sample.
• Computed tomography or magnetic resonance imaging and sometimes blood tests to check for cysticercosis.

The doctor diagnoses teniasis by identifying fragments of the worm or its egg in a stool sample.

In people with cysticercosis, cysts in the brain and other tissues can be seen with computed tomography (CT) or magnetic resonance imaging (MRI). Blood tests for antibodies to pork tapeworm can also aid in the diagnosis. Antibodies are proteins produced by the immune system to protect the body from attacks, including parasites. Sometimes hardened cysts can be felt under the skin.

Treatment of teniasis

Treatment includes the following:

• For intestinal infections, praziquantel or nitazoxanide (antiparasitic drugs).
• For symptoms caused by cysticercosis, in some cases, corticosteroids, as well as any antiparasitic drug with or without surgery.

A person infected with intestinal tapeworm is treated with a single oral dose of praziquantel. For dwarf tapeworm infection, nitazoxanide can be used instead.

- Treatment of cysticercosis.

Treatment for cysticercosis is determined by various factors such as symptoms and the number and location of cysts in the brain.

Typically, cysticercosis does not require treatment unless it affects the brain. Corticosteroids such as prednisone are given to people with symptoms caused by cysts in the brain. These drugs can help reduce the intensity of inflammation. Anticonvulsants are prescribed for people with epilepsy.

Antiparasitic drugs (such as albendazole or praziquantel) can be used to kill live cysts in the brain, but they are prescribed after symptoms have been appropriately controlled. Corticosteroids are also prescribed with an antiparasitic agent to minimize inflammation caused by dying cysts.

Antiparasitic drugs are not used to treat cysts in the eyeball or spinal cord because they can cause severe inflammation that can damage surrounding tissues.

In some cases, surgery is required: for example, when cysts block the flow of fluid, washing the brain and spinal cord (cerebrospinal fluid), or when they create problems in the spinal cord or eyes.

Prophylaxis

The first line of defense against tapeworms is the following:

• Thoroughly cook whole cuts of meat and freshwater fish at temperatures above 63 ° C for three minutes or longer.

If the meat is minced, a cooking temperature of at least 71 ° C is recommended.

Whole cuts of meat should be set aside for 3 minutes after cooking before slicing and eating. Ready-made minced meat can be consumed immediately.

Freshwater fish should not be served raw (such as sushi) and should only be eaten after being cooked at at least 63 ° C or properly frozen at temperatures lower than standard household freezers. With the help of these measures, the broad tapeworm is destroyed.

The following are the recommended methods for freezing freshwater fish:

• At -20 ° C or below for 7 days.
• At -35 ° C or below until cured, then stored at -35 ° C or below for 15 hours.
• At -35 ° C or below until cured, then stored at -20 ° C or below for 24 hours.

Smoking and drying will not kill cysts.

Next line of defense:

• Careful inspection of meat and fish by experienced professionals.

Cysts are visible in contaminated meat.

Proper handling of human excreta interrupts the life cycle of worms and helps prevent infections caused by porcine and bovine tapeworm, including cysticercosis.

Dwarf tapeworm infection can be prevented by avoiding:

• food and water that may be contaminated with feces;
• grains in which infected insects may be present.

For example, when traveling to countries where there is a possibility of food contamination with human feces, you should wash vegetables and fruits before eating them with clean water, peel them off and / or subject them to heat treatment.

Hand washing with soap and warm water after using the toilet, changing diapers and before preparing food is also effective.