Cysticercosis

Unique identifier / Notation

BI0112

Synonyms

Cysticercus cellulosae Infection Human Cysticercosis Cysticercosis neurocysticercosis (NCC) Porcine Cysticercosis Taenia solium Taenia solium Cysticercoses Taeniasis pork tapeworm infection

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Cysticercosis is a preventable infection in humans and pigs caused by the larval stages of the parasite Taenia solium (pork tapeworm). Human cysticercosis can result in devastating effects when the larvae are located in the central nervous system, resulting in neurocysticercosis which may cause convulsions and epileptic seizures and can be fatal. It is the main cause of preventable epilepsy where the parasite is present, and it is estimated to affect between 2.56 and 8.30 million people (adapted from WHO, 2023).

Primary reference(s)

WHO, 2023. Taeniasis and cysticercosis. World Health Organization (WHO). Accessed 26 May 2025.

WHO, 2023. New OpenWHO course: Toolbox for the control and management of Taenia solium Accessed 26 May 2025.

WOAH. No date. Porcine cysticercosis. Accessed 26 May 2025.

Annotations

Additional scientific description

Taenia solium is a zoonotic parasite whose life cycle involves both humans and pigs. The parasite, Taenia solium, causes three diseases: taeniasis in humans, cysticercosis in pigs and cysticercosis in humans. T. solium is included in the WHO portfolio of Neglected Tropical Diseases.

Human

Taeniasis in humans is acquired when people undercooked infected pork that contains T. solium larvae, which then develop into adult tapeworms in the small intestine. Taeniasis in humans is usually asymptomatic or characterized by mild/non-specific symptoms such as abdominal pain or diarrhoea. Symptom onset occurs when the tapeworms become fully developed in the intestine, usually approximately 8 weeks following ingestion. These symptoms may continue until the tapeworm dies following treatment, otherwise it may live for several years. Human tapeworm carriers excrete tapeworm eggs in their faeces and contaminate the environment when they defecate in open areas. Ingestion of the excreted tapeworm eggs from the environment causes human and porcine cysticercosis.

Human cysticercosis is transmitted through the ingestion of tapeworm eggs through the faecal oral route or contaminated food/water. The ingested eggs develop into larvae that encyst in the muscles, under the skin, eyes or in the central nervous system causing neurocysticercosis, which is the most serious disease caused by T. solium. Most neurocysticercosis is asymptomatic, however, the most common features are seizures, and it is the leading cause of preventable epilepsy worldwide. Cysts lodged in different parts of the brain give rise to unique clinical syndromes such as s focal epilepsy, epileptic seizures, hydrocephalus, chronic headaches, and symptoms associated with increased intracranial hypertension. The incubation period prior to the appearance of clinical symptoms varies, and infected people may remain asymptomatic for many years.

The internationally recognized criteria for diagnosis of neurocysticercosis include a requirement for neuroimaging techniques, such as computerized tomography (CT) and/or magnetic resonance imaging (MRI), ideally supported by serology. These facilities are not available in all settings, especially in rural areas of low-income countries, making it difficult to identify and treat patients. Therefore, the prevalence of infection and disease, morbidity, and mortality are probably grossly underestimated. The management of neurocysticercosis may include anthelmintic, anti-inflammatory and antiepileptic drug (AED) treatments, and neurosurgery in some cases as detailed in the WHO guidelines on the management of cysticercosis (WHO, 2021).

Animal

Swine are the usual intermediate host for T. solium but humans, the usual definitive host, can serve as accidental intermediate hosts following ingestion of infectious eggs (CDC, 2019). Specific control measures in the pig population include the vaccination of pigs with the TSOL18 vaccine and the treatment with oxfendazole. Vaccination prevents the pigs from getting infected; oxfendazole cures the pigs already infected at the time of vaccination, and both can be given simultaneously (WHO, no date).

Metrics and numeric limits

T. solium is endemic in 51 countries, with a further 14 countries suspected endemic mostly in Africa, Asia and Latin America (WHO, 2022 b).

The total number of people with symptomatic or asymptomatic neurocysticercosis is estimated to be 2.56-8.30 million. The greatest burden of T. solium-induced disease is due to neurocysticercosis, which is estimated to contribute to approximately 30% of epilepsy cases in areas where the disease is endemic. However, in specific communities, it can be up to 70%. Approximately 80% of people with epilepsy live in low- and middle-income countries and most do not receive appropriate treatment (WHO, 2022b).

In Latin America, it is estimated that in 2010 there were 30 859 cases of neurocysticercosis (NCC) and 960 deaths, causing 180 829 years of disabilities-adjusted life (DALYs) (PAHO, no date)

Key relevant UN convention / multilateral treaty

International Health Regulations (2005), 3rd ed. (WHO, 2016).

Drivers

Key drivers for cysticercosis include the number of backyard pigs and the prevalence of open rural defecation.

Taeniasis is the intestinal infection of the adult tapeworm. When left untreated, a more serious condition known as cysticercosis develops as T. solium larvae invade body tissues. When larvae build up in the central nervous system, muscles, skin and eyes, it leads to neurocysticercosis - the most severe form of the disease and a common cause of seizures worldwide (WHO, 2018)

T. solium taeniasis is acquired by humans through the ingestion of the parasite's larval cysts (cysticerci) in undercooked and infected pork. Human tapeworm carriers excrete tapeworm eggs in their faeces and contaminate the environment when they defecate in open areas. Humans can also become infected with T. solium eggs due to poor hygiene (via the faecal-oral route) or ingesting contaminated food or water (WHO, 2022a).

Ingested T. solium eggs develop into larvae (called cysticerci) in various organs of the human body. When they enter the central nervous system, they can cause neurological symptoms (neurocysticercosis), including epileptic seizures. T. solium is the cause of 30% of epilepsy cases in many endemic areas where people and roaming pigs live in close proximity. In high-risk communities it can be associated with as many as 70% of epilepsy cases (WHO, 2022a).

Impacts

T. solium produces a significant societal impact. Neurocysticercosis carries a significant economic burden, increasing poverty through high treatment costs for patients and their families and the healthcare system. This is compounded by the economic losses associated with porcine cysticercosis through loss of value from infected pigs, Furthermore, many patients specifically female patients face discrimination and stigma due to the symptoms of epilepsy (which is associated with witchcraft), increasing inequalities.

Multi-hazard context

More than 80% of the world's 50 million people who are affected by epilepsy live in low and lower-middle-income countries (WHO, 2022 a). Neurocysticercosis is the most frequent preventable cause of epilepsy worldwide and is estimated to cause 30% of all epilepsy cases in countries where the parasite is endemic. In specific communities, the association between neurocysticercosis and epilepsy can be up to 70%. In poor remote settings where the disease is present, epilepsy is difficult to diagnose and treat, and causes major stigma, especially in girls and women (WHO, 2022a)

Cysticercosis mainly affects the health and livelihoods of subsistence farming communities in developing countries of Africa, Asia and Latin America. It also reduces the market value of pigs and makes pork unsafe to eat (WHO, 2022a)

In the WHO Taenia solium endemicity map - 2022 update, it was reported that of the 196 countries and territories assessed, 51 were classified as endemic for T. solium, 14 as suspected endemic, 21 as having few pigs exposed to risk factors and 55 as not endemic. There was insufficient data for 59 countries and no data or possible transmission in some communities in 14 countries (WHO, 2022b).

Risk Management

T. solium cysticercosis remains a neglected disease because of a lack of general awareness, lack of information on disease burden, a paucity of validated tools for field diagnosis, lack of resources for control and treatment, poor access to neuroimaging and neurological care and hesitation to invest in zoonotic neglected tropical diseases.

Human

The control and elimination of T. solium are hindered by many factors, including the lack of reliable epidemiological data on infections in people and pigs. Appropriate surveillance and point-of-care diagnostic tools would enable identification and targeted interventions in high-risk communities. Key preventative measures include preventive chemotherapy for taeniasis, and a One Health approach involving vaccination and anthelmintic treatment of pigs to prevent infection with T. solium cysticerci. Health promotion and awareness of the community are necessary to support those interventions. Other interventions require a longer-term approach such as improved pig management practices to prevent exposure of pigs to human faeces; improved sanitation to prevent contact between pigs or humans and T. solium eggs in human faeces and in the environment; meat inspection and sufficient cooking of pork to reduce the risk of humans becoming infected and health education to promote hand hygiene, food safety, sanitation and pig management (WHO, 2023).

Animal

Prevention and control in animals include Improved pig-farming practices; Vaccination of pigs with TSOL18; Treatment of pigs with oxfendazole; Meat inspection, meat processing (freezing) (FAO, OIE & WHO, 2021).

Monitoring

The table below offers an overview of monitoring for cysticercosis. This information can be used for forecasting within a national early warning system (EWS). Since EWS capacities and processes differ across countries, the most current and specific information regarding EWS should be obtained from the appropriate national or regional agency/authority responsible for disaster management.

Which institution(s) produce(s) Disaster Risk Data/Information?

WHO, Ministry of Health

WOAH Reference Centres

How is the Hazard Observed/Monitored/Forecast?

WHO, Ministry of Health

FAO empres-i+ https://empres-i.apps.fao.org/diseases

WOAH WAHIS https://wahis.woah.org/#/event-management

WHO supports countries to conduct all-hazards strategic risk assessment in the contexts of health emergencies and disasters, which results in the development of a country risk profile. Empowered with the country risk profile, inclusive of a seasonal risk calendar, countries can anticipate potential emergencies before they occur to trigger early alerts and inform early actions (WHO, 2021).

Robust surveillance data is fundamental to assess disease burden, take action and evaluate progress. As for other neglected diseases, data is especially scarce. WHO is active in countering this situation by collecting and mapping data on T. solium distribution and risk factors associated with the occurrence of the parasite, such as information on pig keeping, food safety and sanitation. This information has been incorporated into the WHO Global Health Observatory (WHO, 2022a).

WHO's Early Warning, Alert and Response System (EWARS) has been designed to improve disease outbreak detection in emergency settings, such as in countries in conflict or following a natural disaster. It is a simple and cost-effective way to rapidly set up a disease surveillance system. EWARS is deployed during an emergency as an adjunct to the national disease surveillance system. WHO works with Ministries of Health and health sector partners to train local health workers to use the system. After the emergency, EWARS should re-integrate back into the national system (WHO, no date).