A British woman who was found to have 38 parasitic cysts in her brain believes she contracted the infection during a two-month visit to India in 2007, according to reports by UK media. Lowri Denman, 42, was diagnosed with neurocysticercosis, a rare parasitic disease caused by the pork tapeworm, Taenia solium. The disease affects the brain and nervous system and is one of the leading preventable causes of epilepsy worldwide. According to the BBC, Denman is among only a small number of people diagnosed with the condition in the UK each year.
Denman first noticed something unusual in 2011, four years after returning from India, when she found a metre-long tapeworm after using the toilet, the BBC reported. An MRI scan later detected 38 parasitic cysts in her brain. She subsequently underwent prolonged treatment and now requires lifelong medication to manage epilepsy resulting from the infection.
However, whether she contracted the disease during her visit to India cannot be established with certainty. According to the World Health Organization (WHO), neurocysticercosis develops after a person ingests microscopic Taenia solium eggs through food or water contaminated with human faeces, usually due to poor sanitation or hygiene.
Consuming raw or undercooked pork infected with the parasite can cause an intestinal tapeworm infection, but this alone does not directly lead to neurocysticercosis. Denman told the BBC that she intentionally avoided animal products while in India. However, infectious diseases consultant Dr Brendan Healy said she most likely acquired the infection in India after inadvertently ingesting microscopic tapeworm eggs. Here are three important facts about the disease and one key question.
Fact One: Tapeworm infections are not limited to pork
According to the BBC, Denman's doctor suggested she developed the infection after "inadvertently eating pork that contained microscopic tapeworm eggs."
Although Taenia solium is commonly referred to as the pork tapeworm, tapeworm infections can originate from several different sources depending on the species involved.
Raw or undercooked pork may transmit Taenia solium, undercooked beef can carry Taenia saginata (beef tapeworm), while raw or undercooked freshwater fish may transmit fish tapeworms such as Diphyllobothrium species.
Among these, only Taenia solium can cause neurocysticercosis, in which tapeworm larvae invade the brain and central nervous system.
According to the WHO and the US Centers for Disease Control and Prevention (CDC), neurocysticercosis occurs when a person ingests microscopic eggs shed in the faeces of someone carrying an adult pork tapeworm. These eggs can contaminate many types of food—not only pork—but also raw fruits, vegetables and other ready-to-eat items handled by an infected individual with poor hand hygiene.
By contrast, eating infected pork, beef or fish generally results in an intestinal tapeworm infection rather than larvae spreading to the brain.
Fact Two: Contaminated water can also spread the infection
Apart from contaminated food, drinking contaminated water is another major route of transmission.
People develop neurocysticercosis after swallowing microscopic Taenia solium eggs present in water contaminated with human faeces. These eggs can also contaminate food and surfaces in areas with poor sanitation and inadequate hygiene.
According to the WHO, the eggs are excreted in the faeces of individuals carrying an adult pork tapeworm. In places with inadequate sanitation and sewage systems, they can enter water supplies. Once ingested, the eggs hatch in the intestine, and the larvae migrate through the bloodstream to the brain, muscles and other tissues, where they develop into cysts.
This differs from an intestinal tapeworm infection, which results from eating undercooked pork. Neurocysticercosis specifically develops after ingesting the parasite's eggs through food or water contaminated with human faeces.
The infection may also occur if a person accidentally swallows water while swimming in unmanaged rivers or natural water bodies in endemic regions with poor sanitation. However, the risk of acquiring the disease from properly chlorinated and filtered swimming pools is considered extremely low.
Fact Three: Rare in the UK, but endemic in India
Neurocysticercosis is extremely uncommon in the UK because of strict food safety regulations, modern sanitation systems, regulated pig farming and effective meat inspection.
A study conducted by the Hospital for Tropical Diseases in London identified only 26 active cases between 2001 and 2015, averaging fewer than two cases annually.
Among those cases, 65.4 per cent occurred in immigrants, while the remaining 34.6 per cent involved UK-born travellers who had visited endemic regions in South and Central America, sub-Saharan Africa, and South and Southeast Asia.
India, however, remains one of the countries where the disease is endemic. According to the WHO, neurocysticercosis is widespread across parts of Asia, sub-Saharan Africa and Latin America, particularly in areas with poor sanitation where the parasite continues to circulate between humans and pigs. The disease is recognised as one of the leading preventable causes of epilepsy in such regions.
Unlike the UK, India does not maintain nationwide surveillance data because neurocysticercosis is not a nationally notifiable disease. However, a community-based study conducted in Vellore district of Tamil Nadu and published in the Indian Journal of Medical Research found that neurocysticercosis accounted for 28–34 per cent of active epilepsy cases within the study population.
Based on those findings, researchers estimated a national prevalence of approximately one case per 1,000 people, suggesting that more than one million Indians could be living with the disease, although the actual burden likely varies across regions and remains difficult to determine precisely.
Can it be confirmed that the infection was acquired in India?
The short answer is no. It is not possible to determine with certainty where Lowri Denman contracted neurocysticercosis, as there is no laboratory test capable of identifying the country or exact location where exposure occurred.
Instead, doctors rely on a patient's travel history, the prevalence of the disease in different regions and the likely period of exposure to make an informed clinical assessment.
In Denman's case, her two-month stay in India in 2007 is considered the most probable source because India is an endemic country for neurocysticercosis, whereas the disease is exceptionally rare in the UK.
She also developed an intestinal tapeworm before brain scans revealed multiple parasitic cysts, indicating that the infection had likely occurred years earlier. Such long intervals between exposure and diagnosis are well documented, as the cysts can remain dormant for months or even years before causing symptoms such as seizures.
Nevertheless, it is impossible to exclude every other possible source of infection. Since neurocysticercosis results from ingesting microscopic tapeworm eggs through contaminated food or water, exposure could theoretically occur anywhere the parasite is present.
Dr Brendan Healy's conclusion that Denman most likely acquired the infection during her stay in India is therefore based on clinical probability, taking into account her travel history and the known epidemiology of the disease, rather than definitive evidence identifying the precise place where the infection occurred.
