Taeniasis (tapeworm)

Notification requirement for taeniasis

Notification is not required.

Primary school and children’s services centres exclusion for tetanus

School exclusion is not required.

Infectious agent of taeniasis

Taenia solium (pork tapeworm) causes both intestinal infection with the adult tapeworm and somatic infections with the larvae (cysticerci).

T. saginata (beef tapeworm) causes only intestinal infection with the adult tapeworm in humans.

Identification of taeniasis

Clinical features

T. saginata infections are often asymptomatic, apart from the anal passage of tapeworm segments. Infection may be associated with epigastric pain, diarrhoea and weight loss.

T. solium adult worm infections are also usually asymptomatic. Many tissues and organs may be infected by the larval form (cysticercosis). Neurocysticercosis is a serious but rarely fatal complication, which may manifest as headaches, epileptiform seizures, and visual or psychiatric disturbances.

Diagnosis

Infection with an adult tapeworm can be diagnosed through the identification of segments, eggs or the head of the parasite in faeces or perianal swabs. Microscopic examination of the eggs cannot differentiate between the two species.

Specific serological tests are available to support the clinical diagnosis of taeniasis.

Subcutaneous cysticerci may be visible or palpable. Calcified cysticerci may be visualised using ultrasound, computed tomography (CT) scan or magnetic resonance imaging (MRI).

Incubation period for taeniasis

Symptoms of cysticercosis may appear from weeks to years after infection. Eggs appear in the faeces 8–12 weeks after infection with the adult T. saginata tapeworm and after 10–14 weeks for T. solium.

Public health significance and occurrence of taeniasis

Taeniasis occurs worldwide. It is commonly seen in parts of Latin America, Africa, South-East Asia and eastern Europe. Both forms are usually imported to Australia, but sporadic locally acquired cases of T. saginata infection have been reported.

Many infections are largely asymptomatic, but the larval stage of T. solium may cause fatal cysticercosis. Chronic tapeworm infections contribute to malnutrition in developing communities in many parts of the world.

Reservoir for Taenia

Humans are the definitive host for both species. Cattle are the intermediate host for T. saginata and pigs for T. solium.

Mode of transmission of Taenia

Eggs of T. saginata passed in the faeces of an infected person are only infectious to cattle. Humans are infected by ingestion of raw or undercooked beef infected with Cysticercus bovis, the larval stage of T. saginata. In humans, the adult tapeworm develops in the intestine over 2–3 months. The cycle of infection repeats when infectious eggs are passed in the faeces and later ingested by cattle, slowly migrating into the flesh and transforming into the larval stage.

Infections by T. solium may follow a similar cycle, with consumption of infected pork leading to the subsequent development of adult tapeworms. However, human infection may also occur through the consumption of T. solium eggs. This occurs by direct transfer from the faeces of an infected person, or through ingestion of contaminated food or water. When the eggs of T. solium are ingested by either humans or pigs, the embryos escape the shells and penetrate the intestinal wall, with subsequent spread of larvae to various tissues to produce cysticercosis.

Period of communicability of taeniasis

T. saginata is not directly transmissible from person to person, but T. solium may be. Adult tapeworms may persist in the intestines for up to 30 years and are able to disseminate eggs for all of this time. Eggs may remain viable in the environment for months.

Susceptibility and resistance to taeniasis

Everyone is susceptible to infection. Infection does not appear to confer immunity.

Control measures for taeniasis

Preventive measures

The public should be advised to avoid faecal contamination of soil, and human and animal food; avoid the use of raw sewage for irrigation of pasture soil; and cook beef and pork thoroughly.

Beef and pork should be adequately cooked – for example, at 60 °C for 5 minutes.

Freezing meat below –5 °C for more than 4 days will kill cysticerci.

Meat should be routinely inspected for evidence of taeniasis at slaughter.

Control of case

Praziquantel or niclosamide are used for treatment of beef and pork tapeworm infections. Consult the current version of Therapeutic guidelines: antibiotic.

People harbouring adult T. solium should be immediately identified and treated to prevent human cysticercosis. For cysticercosis, surgical intervention may relieve symptoms. For central nervous system cysticercosis, praziquantel or albendazole may be used, with corticosteroids if indicated.

Isolation is not required. The case and relevant caregivers should be advised that the case’s faeces may be infectious, and advised on sanitary disposal of wastes.

Control of contacts

Symptomatic patients exposed to a suspected source of infection should be evaluated for evidence of taeniasis.

Control of environment

If the history is consistent with local infection, the source of the infection should be investigated, often with the assistance of the local government.

Outbreak measures for taeniasis

Not applicable.