Neurocysticercosis

22 February 2018

Tapeworm infection of the central nervous system is a leading cause of epilepsy worldwide

Neurocysticercosis is a preventable parasitic infection of the central nervous system and is caused by the pork tapeworm Taenia solium. Humans become infected after consuming undercooked food, particularly pork, or water contaminated with tapeworm eggs, or through poor hygiene practices.

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.

This fact file features key information about neurocysticercosis.

WHO/C. Gaggero

Pigs become infected with T. solium when they come into contact with human faecal waste

Millions of tapeworm eggs are excreted into the environment through the faeces of infected people. When pigs ingest these eggs or eggs from the environment, small cysts develop throughout the animal’s body. Humans are infected by consuming food, such as raw or undercooked pork, or water contaminated with tapeworm eggs, or through poor hygiene practices.

Neurocysticercosis and taeniasis are two different diseases caused by the same parasite

When the parasite T. solium is transmitted to human beings, it causes an intestinal infection of the adult tapeworm known as taeniasis. If left untreated, the tapeworm can survive inside the body for many years, leading to more serious conditions. Cysticercosis develops when the larvae of T. solium invade body and develop in the muscles, skin and eyes. If larvae invade the central nervous system, the infection leads to neurocysticercosis.

J. Latels

50 million people are affected by epilepsy. More than 80% live in the developing world

Neurocysticercosis is the most frequent preventable cause of epilepsy in the developing world. It is a common infection of the human nervous system and a growing public health concern. Symptoms of neurocysticercosis can include chronic headaches, blindness, seizures, meningitis and dementia.

ILRI / Charlie Pye-Smith
Inspecting a pig's health in Busia, western Kenya in 2010

Taenia solium was recently named the food-borne parasite of "greatest global concern"

WHO together with the Food and Agriculture Organization recently issued the warning to highlight the importance of cross-sector collaboration in tackling the spread of the disease. The combined efforts of sectors such as health, veterinary services and education can largely help to control T. solium infections. Behaviour change efforts can also be integrated with other disease programmes and interventions in settings where such resources are limited.

Lian Thomas

Neurocysticercosis is prevalent mainly in developing countries

For decades, Latin America has had a serious problem with cysticercosis and neurocysticercosis. The disease is endemic in South and South-East Asia, and is emerging in parts of sub-Saharan Africa, particularly in rural areas where animal husbandry practices allow pigs to come into contact with human faeces. In many countries, a lack of awareness and understanding about the condition means it is largely a neglected disease.

ILRI/Charlie Pye-Smith
Pigs scavenge for food on a street in Busia. Kenya

Neurocysticercosis mainly affects rural farming communities

The disease occurs in countries where families engage in community farming practices and raise free-roaming pigs. It is also common in areas where animals are slaughtered outside approved abattoirs and in the absence of meat inspections. T. solium infection in pigs affects the livelihood of many communities as pigs lose their market value.

ILRI/HUPH/Ngan Tran
Selling pork at a traditional 'wet' market in Hung Yen province, northern Vietnam

Food handlers can also transmit Taenia solium

Neurocysticercosis is not just limited to rural areas or disadvantaged communities lacking basic sanitation. A growing concern is the lack of hygiene practices among food handlers where the practice of regular hand-washing is important. Food safety, improved sanitation and hygiene are all crucial to preventing the transmission of T. solium. Cooking pork thoroughly also kills the parasite.

Mount Sinai health System
Taenia cysts in the brain

Diagnosis of neurocysticercosis is difficult in rural regions

Diagnosis of suspected neurocysticercosis currently requires computed tomography scans (CT scans). These facilities are not usually available in rural areas, where the disease is most prevalent, making it difficult to identify and treat patients. It is important to control the parasite by finding and treating people with the condition – and therefore avoid chances of transmission.

WHO NTD
Children waiting for drug distribution in Madagascar

Treatment for neurocysticercosis can be long, complicated and costly

Neurocysticercosis is creates tremendous economic burden on health systems as treatments need to be tailored according to individual needs. Long courses of praziquantel and/or albendazole, as well as supportive epileptic therapy can improve the quality of life for patients. Fortunately, pigs can now be treated with anti-parasitic medications and vaccinated against <i>T. solium</i>. This prevents the parasite from being transmitted to humans.

ILRI/Charlie Pye-Smith
A typical household scavenging pig and pit latrine in Busia, Kenya

Eliminating neurocysticercosis requires breaking the life cycle of T. solium

Thorough case finding, better diagnosis and treatment, and public health information campaigns are crucial to effectively control and break the life cycle of the parasite. Many sectors need to be included with activities which can reduce the risk of infection. WHO is working with countries to tailor intensified control strategies for <i>T. solium</i> and improve management of neurocysticercosis patients. Partners include the FAO, the World Organisation for Animal Health, private sector, NGOs and academia.