Neurocysticercosis: tapeworm cysts in the brain and nervous system

The World Health Organization (WHO) explains that Taenia solium is a zoonotic tapeworm found globally but with particularly high transmission in parts of Latin America, South and South-East Asia and sub-Saharan Africa. Depending on its life cycle it causes two distinct presentations in humans: taeniasis, an intestinal tapeworm infection, and cysticercosis, in which larvae form cysts in the muscles, skin, eyes or central nervous system.

Neurocysticercosis is the form in which cysts develop in the central nervous system. Patient.info’s clinical article, written for medical professionals in the UK, describes how cysticercosis arises when T. solium larval cysts infiltrate the lung, liver, eye or brain, causing inflammation and neurological symptoms.

No NHS or UK government patient page on neurocysticercosis was found when this guide was prepared, so the main source here is the WHO, supported by a UK clinical summary. Specialist infectious diseases and neurology teams manage the condition.

The WHO notes that people with taeniasis do not have severe disease themselves, but they shed T. solium eggs, which can infect both pigs and humans. The resulting larvae form cysts in the muscles, skin, eyes or central nervous system. Patient.info’s article describes the life cycle of the adult tapeworm in humans following ingestion of poorly cooked meat containing larval cysts, with eggs excreted in faeces.

It also advises prevention measures such as inspecting meat thoroughly, adequate handling of food including freezing or cooking, and notes that cysticerci do not survive temperatures below 10°C and above 50°C. The WHO advocates periodic treatment for tapeworms in endemic areas, which can prevent neurocysticercosis at a later stage, according to the article.

Symptoms depend on where the cysts are and how the body responds to them. The WHO lists focal epilepsy, epileptic seizures, hydrocephalus, chronic headaches, focal deficits and symptoms associated with increased intracranial hypertension. Many people with infection may have no symptoms for a long period, and the WHO notes the number of people with symptomatic or asymptomatic neurocysticercosis is estimated to be 2.56 to 8.30 million.

Patient.info’s article states that in some countries, for example Peru and Mexico, neurocysticercosis accounts for 30% of seizures, which makes it an important cause of morbidity and mortality worldwide. The WHO adds that it is estimated to contribute to up to 30% of epilepsy cases in endemic areas.

• Seizures, including focal seizures.

• Chronic or severe headaches.

• Focal neurological deficits, such as weakness.

• Signs of raised pressure inside the skull, or hydrocephalus.

Any first seizure, sudden severe headache, new weakness or confusion needs urgent medical assessment, whatever the cause. In the UK that means calling 999 or going to A&E for a seizure or sudden neurological change. Tell clinicians if you have lived in or travelled to parts of the world where the tapeworm is common, since this changes the list of possible causes.

The sources read do not state how common neurocysticercosis is in the UK, so this is general advice rather than a statement of risk. A GP can refer someone with relevant symptoms and a travel or residence history to infectious diseases or neurology services.

The WHO says the internationally recognised criteria for diagnosing neurocysticercosis include a requirement for neuroimaging techniques such as computerised tomography (CT) and/or magnetic resonance imaging (MRI), ideally supported by serology. It notes these facilities are not available in all settings, which makes diagnosis difficult in rural areas of low-income countries.

Patient.info’s article says cysticercosis is confirmed by the presence of antibodies and imaging, for example CT scan of the brain. The same article says eggs or proglottids can be recovered from stool or the perianal area to identify intestinal tapeworm infection.

The WHO says there is controversy about the role, type and duration of anthelmintic (antiparasitic), anti-inflammatory and antiepileptic drug treatments for different forms of neurocysticercosis, and that its guidelines were developed to assist health-care providers in managing parenchymal neurocysticercosis, in which cysts are within the brain tissue. They do not address other forms, such as cysts in the cerebral ventricles or subarachnoid space.

Patient.info’s article states that for intestinal tapeworm infection, niclosamide or praziquantel as a single dose can be used, available on a named-patient basis in the UK. Treatment of neurological disease is more complex and is decided by specialist teams; the sources read do not give a regimen, so none is given here.

The WHO describes neurocysticercosis as one of the leading preventable causes of epilepsy worldwide. The WHO says the eggs shed by people with taeniasis can infect pigs and humans, and Patient.info’s article lists inspecting meat thoroughly, handling food adequately, freezing or cooking, and the WHO-advocated periodic treatment of tapeworms in endemic areas.

For UK travellers, the sources read do not give destination-specific advice. A travel clinic can advise on food and water precautions for the region you are visiting, and on any symptoms to report after returning.

In the NHS, suspected neurocysticercosis would normally be assessed by infectious diseases or neurology teams after GP or hospital referral. Treatment is free at the point of use.

Private care may offer faster neuroimaging or specialist consultation. Because treatment can involve antiparasitic drugs and steroids, ask which team will monitor your care and how seizures will be managed, and inform your GP of all treatment received.