Taeniasis
Cysticercosis
Tapeworms can cause epilepsy

Teaniasis is a food-borne disease caused by mainly three parasites, commonly known as tapeworms. Cysticercosis is a tissue infection caused by the proliferation of tapeworms in the body. In most people they do not cause serious issues by occasionally the disease migrates to the brain where it can cause serious issues. Cysticercosis is the most common cause of symptomatic epilepsy worldwide.

It is uncommon in the developed world, but in some areas up to 25% of people are affected. It rarely causes deaths, but still at least 50 000 per year. There is also a risk for disability when it infects the brain. Tapeworms affect about 50 million people globally.

What causes Taeniasis and Cysticercosis

Taeniasis is caused when a human is infected with the adult form of the pork or beef tapeworm while cysticercosis is caused when a human becomes infected with the larval stage of only the pork tapeworm, Taenia solium.

Consuming undercooked pork is not the cause of cysticercosis. Should the pork have larval cysts, consumption of undercooked pork could, then, lead to intestinal tapeworm. Cysticercosis is usually acquired by eating food or drinking water contaminated by tapeworm eggs from human feces. Among foods, uncooked vegetables are the major source.

The intestinal infection caused by 3 species of tapeworm: Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm) and Taenia asiatica. aenia saginata is due to eating contaminated undercooked beef while Taenia solium and Taenia asiatica is from contaminated undercooked pork.

Photo: Head of Taenia solium tapeworm.

Where are Taenia found

Taeniasis and cysticercosis can be found globally with the highest infection rates noted in Africa, Latin America, and Asia.

Taeniasis and cysticercosis are often present in rural parts of developing countries. Cysticercosis is most prevalent where humans live in close contact with pigs. High prevalence is reported in Mexico, Latin America, West Africa, Russia, India, Pakistan, North-East China, and Southeast Asia. In Europe it is most widespread among Slavic people.

Image: Geographical distribution of taenia.

In Latin America, an estimated 75 million persons live in endemic areas and 400,000 people have symptomatic disease. In areas of Guatemala, Bolivia, and Peru infection rates as high as 20 percent in humans, and 37 percent in pigs have been found. In Ethiopia, Kenya and the Democratic Republic of Congo around 10% of the population is infected, in Madagascar 16%.

The earliest reference to tapeworms were found in the works of ancient Egyptians that date back to almost 2000 BC.

What are the symptoms of Taeniasis and Cysticercosis

Infections with the pork tapeworm (T. solium) are normally asymptomatic. A complication, known as cysticercosis, may occur if the eggs of the pork tapeworm are eaten. This typically occurs from vegetables or water contaminated by feces from someone with pork tapeworm taeniasis. The eggs enter the intestine where they develop into larvae which then enter the bloodstream and invade tissues. It can lead to headaches, dizziness, seizures, dementia, hypertension, lesions in the brain, blindness, tumor-like growths, and low eosinophil levels. It is a cause of major neurological problems, such as hydrocephalus, paraplegy, meningitis, and death.

Infections with the beef tapeworm (T. saginata) is generally asymptomatic, but heavy infection causes weight loss, dizziness, abdominal pain, diarrhea, headaches, nausea, constipation, chronic indigestion, and loss of appetite. It can cause an allergic reaction and is also a rare cause of ileus, pancreatitis, cholecystitis, and cholangitis.

Infection with the Asian tapeworm (T. asiatica) is also usually asymptomatic.

How can Taeniasis and Cysticercosis be prevented

Proper cooking of meat is an effective prevention. Freezing meat at −10 °C for 5 days or long periods of salting kills the parasites.  Contaminated hands are also a cause, and especially concerning among food handlers.

Clean and peel any raw fruits and vegetables prior to consumption. While in developing countries boil drinking water or consume bottled water.

Prevention efforts include properly cooking meat, treating active cases in humans, vaccinating and treating pigs against the disease, stricter meat-inspection standards, health education, improved sanitation, and improved pig raising practices. Preventing human feces from contaminating pig feeds also plays a role. Infection can be prevented with proper disposal of human feces around pigs.

How are Taeniasis and Cysticercosis diagnosed

Diagnosis of taeniasis is mainly using stool sample, particularly by identifying the eggs. However, this has limitation at the species level because tapeworms basically have similar eggs.

Polymerase chain reaction (PCR) tests, such as the ones available from the WoIDMo are used to identify the exact species.

Diagnosis of cysticercosis requires biopsy of the infected tissue. Imaging, such as X-ray, CT scans, MRI and ultrasound are used to determine the location of cysts and the extent of the disease.

How are Taeniasis and Cysticercosis treated

Anthelmintics Praziquantel and niclosamide are the treatment of choice for taeniasis. Both drugs present problems in terms of availability in several countries.

Usual treatments are with praziquantel (5–10 mg/kg, single-administration) or niclosamide (adults and children over 6 years: 2 g, single-administration after a light breakfast, followed after 2 hours by a laxative; children aged 2–6 years: 1 g; children under 2 years: 500 mg).

Albendazole at 400 g for 3 consecutive days, is also highly effective.

In neurocysticercosis, since the destruction of cysts may lead to an inflammatory response, specialised treatment of active disease is required and may include long courses with high doses of praziquantel and/or albendazole, as well as supporting therapy with corticosteroids and/or anti-epileptic drugs, and possibly surgery.

In eye disease, surgical removal is necessary for cysts within the eye itself as treating intraocular lesions with anthelmintics will elicit an inflammatory reaction causing irreversible damage to structural components. Cysts outside the globe can be treated with anthelmintics and steroids.

Treatment recommendations for subcutaneous cysticercosis includes surgery and antihelmintics.

 

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