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Pork tapeworm (Taenia Solium)

What is Taenia Solium (pork tapeworm) infection?

Taenia solium infection – also known as pork tapeworm – is widely endemic across Central, South America, sub-Saharan Africa and Asia. The parasite causes neurocysticercosis (NCC), which has been identified as the leading preventable cause of epilepsy in low- and middle-income countries.

It is estimated that NCC accounts for approximately one third of epilepsy cases in countries where T. solium is endemic.

The parasite thrives in areas of unsafe sanitation, where the environment is contaminated with T. solium eggs, allowing constant exposure to free-ranging pigs. Beyond the human health burden associated with NCC, smallholder pig farmers face a substantial economic burden. Pig cysticercosis reduces the value of pork in food-value chains and leads to infected carcasses being discarded.

One study in Tanzania showed that T. solium accounted for $USD 5 million spent due to NCC-associated epilepsy and $USD 2.8 million lost due to porcine cysticercosis in 2012.

Taenia solium (pork tapeworm) symptoms

  • Symptoms associated with neurocysticercosis including epileptic seizures and other neurological symptoms.
  • Clinical manifestations and severity of symptoms depend on the number, size, location of cysts found in the nervous system and the intensity of the host immune response.

Taenia solium treatment

Human taeniasis can be treated with taenicides including praziquantel and niclosamide. Symptomatic therapy, antiparasitic treatment and surgical intervention are options to manage/treat human neurocysticercosis. Porcine cysticercosis can be treated with oxfendazole (see figure).

Lifecycle of taenia solium

The lifecycle of Taenia solium is complex, involving pigs which act as the intermediate host (porcine cysticercosis) harbouring the larval-stage after consuming T. solium eggs in the environment, and humans which can act as the definitive host (human taeniasis) after consuming the larval-stage from (undercooked or raw) pork meat.

Humans can also act as an accidental intermediate host (human (neuro) cysticercosis).

Opposite: Schematic representation of the transmission cycle of Taenia solium, epitomising a One Health approach. The human (blue), animal (orange), and environment (green) components are represented by inter-locking sections that intersect and form a whole entity whose parts cannot be tackled in isolation. The purple boxes indicate the parasite stages responsible for the main human health burden (associated with neurocysticercosis) and economic impact (due to both neurocysticercosis and porcine cysticercosis) of the disease. The grey boxes highlight the points in the parasite’s life-cycle upon which currently available intervention strategies operate: dark grey boxes indicate biomedical approaches (treatment, vaccination); light grey boxes indicate behaviour- and environment-focussed interventions. Modified from Dixon et al. (2019), and published in Dixon et al. (2021)

How do you prevent pork tapeworm infection?

In humans, properly cooking pork meat is important. Strengthening meat inspection and veterinary capacity to inspect carcasses at slaughter points can limit the larval-stage infection entering the food chain. There is a highly effective vaccine (Tsol18: Cysvax™) that can be used to prevent larval-stage infection in pigs. Minimising or preventing pigs from freely roaming and scavenging for foodstuffs in a community prevents exposure, however many poor farmers rely on this low-cost approach for raising pigs. Improving hygiene and sanitation standards, including building latrines and encouraging use is critical to preventing the exposure of T. solium eggs in humans (therefore preventing human neurocysticercosis).

What Unlimit Health is doing

A 2021research project between Bayer AG, Merck and Unlimit Health looked at the impact of large-scale distribution of the drug praziquantel (PZQ) and its impact on T. solium in Uganda.