Cysticercosis is a parasitic infection caused by the larval form of the pork tapeworm (Taenia solium). When a person swallows the eggs of this tapeworm, the eggs hatch in the intestine, and the tiny larvae travel through the bloodstream to various parts of the body, where they form small, water-filled sacs called cysticerci. These cysts can form in the muscles, eyes, skin and, most dangerously, in the brain.

To understand cysticercosis, it is absolutely essential to distinguish it from another disease caused by the same parasite: taeniasis.

• Taeniasis (The Intestinal Tapeworm): A person gets taeniasis by eating raw or undercooked pork that contains the tapeworm’s larval cysts. In the human intestine, the larva matures into a single, long adult tapeworm, which can grow to be several meters in length. This person has an intestinal worm infection. They are the source of the tapeworm eggs but do not have cysticercosis.
• Cysticercosis (The Tissue Cysts): A person gets cysticercosis by swallowing the microscopic eggs that are passed in the feces of a person who has taeniasis. In this person’s body, the eggs do not become adult tapeworms. Instead, they hatch into larvae that migrate throughout the body to form the damaging tissue cysts.

Therefore, you can get cysticercosis without ever eating pork. The disease is transmitted through the fecal-oral route, from a person who is carrying the adult tapeworm.

The most severe form of the disease is neurocysticercosis (NCC), which occurs when the cysts form in the central nervous system (the brain and spinal cord). The symptoms of NCC are not usually caused by the live cysts themselves, but by the intense inflammatory reaction the body mounts when the cysts begin to die and degenerate. This inflammation can cause swelling, seizures, and increased pressure inside the skull.

In my experience, cysticercosis is often a surprising diagnosis for patients, they may have no idea they’ve been infected until neurological symptoms appear. Education and hygiene play a crucial role in prevention.

Analogy: Imagine the human body as a city. In cysticercosis, unwanted travelers (tapeworm eggs) sneak into the city, settle in different neighborhoods (organs), and build homes (cysts). Some remain quiet, while others disrupt power lines, especially if they reach the brain.

Cysticercosis is caused by infection with the larval stage of the pork tapeworm (Taenia solium). The life cycle of this parasite is complex and requires both pigs and humans to be completed.

1. The Pig (Intermediate Host): The cycle often begins when a pig ingests tapeworm eggs from soil or food contaminated with human feces. The eggs hatch in the pig’s intestine, and the larvae migrate to the pig’s muscles, where they form cysts.
2. Human Intestinal Infection (Taeniasis): A human eats raw or undercooked pork containing these cysts. The cysts mature into an adult tapeworm in the human’s small intestine. This tapeworm attaches to the intestinal wall and can live for years, producing thousands of eggs daily.
3. Human as the Egg Source: The person with the adult tapeworm passes these microscopic eggs in their feces.
4. Human Tissue Infection (Cysticercosis): Another human becomes infected by accidentally swallowing these infective eggs. This can happen through contaminated food, water, or poor hand hygiene. This person becomes an “accidental intermediate host,” and the larvae form cysts in their tissues, causing cysticercosis.

Clinically, I’ve diagnosed this condition in patients who hadn’t eaten pork in years, but lived in environments with poor sanitation or close contact with someone unknowingly carrying a tapeworm.

You get cysticercosis by accidentally ingesting Taenia solium eggs. The infection is transmitted by consuming food or water contaminated with the eggs of the T. solium tapeworm, which can only come from the feces of an infected human.

The most common pathways of transmission include:

• Contaminated Food Preparation: This is the most frequent route of infection. A person who has an adult pork tapeworm (taeniasis) and who does not practice good hand hygiene after using the toilet can contaminate food with microscopic eggs while preparing it for others.
• Drinking Contaminated Water: In areas with poor sanitation, water sources can become contaminated with human fecal matter containing the eggs.
• Contaminated Produce: Eating raw fruits or vegetables that were grown using contaminated water or soil.
• Autoinfection: It is also possible for a person who is already hosting the adult tapeworm to infect themselves with cysticercosis if they have poor hygiene, transferring eggs from their hands to their mouth.

The risk of contracting cysticercosis is highest in rural and developing areas where pigs are raised, where sanitation is poor, and where open defecation is common. However, due to global travel and food distribution, cases can appear anywhere in the world.

Patients are often surprised to learn that you don’t need to eat pork to get this disease, it’s fecal-oral transmission that’s the true culprit.

Cysticercosis symptoms vary depending on where the cysts form, how many are present, and whether the immune system reacts to the cysts. If cysts form only in the muscles, a person may have no symptoms at all and never know they are infected. Most symptoms occur when cysts are in the central nervous system.

Neurocysticercosis (NCC): This is the most common symptomatic form of the disease and is a leading cause of acquired epilepsy worldwide (WHO, 2023). Symptoms are caused by cysts and surrounding inflammation in the brain.

• Seizures and Epilepsy: This is the most common presenting symptom. The onset of new seizures in an adolescent or adult who has never had them before should always raise suspicion for NCC in endemic areas.
• Headaches: Often severe and chronic, caused by increased pressure inside the skull.
• Hydrocephalus (“Water on the brain”): Cysts can become lodged in the brain’s ventricles and block the normal flow of cerebrospinal fluid, causing a dangerous buildup of pressure.
• Other Neurological Symptoms: Depending on their location, cysts can cause confusion, difficulty with balance, disorientation, stroke-like symptoms, or swelling of the brain.

Other forms of the disease are less common:

• Ocular Cysticercosis: Cysts forming in the eye can cause blurry or disturbed vision, swelling, or, in some cases, retinal detachment.
• Muscular and Subcutaneous Cysticercosis: Cysts in the muscles or under the skin are usually asymptomatic but may be felt as small, hard lumps.

I’ve seen patients misdiagnosed with epilepsy or brain tumors, only to later discover that the seizures were caused by cysts in the brain from a tapeworm infection, timely diagnosis makes all the difference.

Diagnosing cysticercosis requires a combination of imaging, clinical suspicion, and sometimes lab testing, especially in patients with neurological symptoms and a history of travel to endemic regions.

• Neuroimaging: This is the cornerstone of diagnosis for NCC.
  • Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) of the brain are the most important tests. These scans can directly visualize the cysts in the brain. They can show whether the cysts are active (viable, fluid-filled), degenerating (inflamed), or inactive (small, calcified dots).
• Blood Tests (Serology): Blood tests can be performed to detect antibodies against the T. solium parasite, which can support a diagnosis, but they are not always definitive on their own.
• Stool Examination: A stool sample may be tested for the presence of tapeworm eggs or segments to see if the patient or a close family contact is the source of the infection.
• Biopsy: In rare cases where a cyst is in an accessible area under the skin, a biopsy of the lump can confirm the diagnosis.

In clinical practice, brain MRI remains the most sensitive test for neurocysticercosis. A good travel and dietary history often raises the first red flag.

Treatment

Cysticercosis treatment is complex and must be managed by a doctor with expertise in infectious diseases or neurology. It depends on the location, number of cysts, and presence of symptoms.

• Symptomatic Treatment: The first priority is to manage the symptoms.
  • Anti-epileptic drugs (AEDs) are used to control and prevent seizures.
  • Corticosteroids (like dexamethasone or prednisone) are used to reduce the inflammation and swelling in the brain caused by the dying cysts.
• Antiparasitic Treatment:
  • Medications like albendazole or praziquantel are used to kill live, active parasitic cysts.
  • It is crucial to understand that antiparasitic treatment can sometimes worsen neurological symptoms. As the cysts are killed, they can trigger a strong inflammatory response.
  • Treatment is not usually given for cysts that are already dead and calcified.
• Surgery: Surgery may be necessary in some cases, such as to remove a cyst that is blocking a fluid pathway in the brain or to place a shunt to treat hydrocephalus.

I always tailor antiparasitic treatment carefully. Killing the cysts too quickly without steroid coverage can cause severe brain swelling. It’s a delicate balance between elimination and control.

Prevention

Cysticercosis is an entirely preventable disease. Prevention strategies are focused on breaking the complex life cycle of the Taenia solium parasite.

1. Preventing Taeniasis (the Intestinal Worm):

• Food Safety: Cook all pork meat thoroughly to a safe internal temperature (above 145°F / 63°C) to kill any larval cysts that may be present. Freezing pork can also kill the larvae.
• Pig Husbandry: Raise pigs in environments where they cannot come into contact with human feces.

2. Preventing Cysticercosis (the Tissue Infection): This is the most critical area for public health intervention.

• Handwashing: Practice thorough handwashing with soap and clean water after using the toilet and before preparing or eating food.
• Food and Water Safety: Wash raw vegetables and fruits. Drink safe, treated water.
• Sanitation: The single most important prevention measure is ensuring the proper, sanitary disposal of human feces and ending the practice of open defecation.

Cysticercosis is a severe parasitic disease that casts a long shadow on global health, serving as a stark reminder of the link between sanitation and disease. While its two-part life cycle is complex, the pathways to prevention are clear. It is critical to dispel the myth that the disease is simply a matter of eating pork; the far more dangerous neurocysticercosis is a disease of hygiene, transmitted from person to person through fecal-oral contamination. Its role as a leading cause of preventable epilepsy makes it a major public health priority. Patients often express relief after finally receiving a diagnosis that explains years of unexplained seizures or headaches. Knowledge empowers both prevention and healing.

Centers for Disease Control and Prevention (CDC). (2023). Parasites – Cysticercosis. Retrieved from https://www.cdc.gov/parasites/cysticercosis/index.html

World Health Organization (WHO). (2023). Taeniasis/Cysticercosis. Retrieved from https://www.who.int/news-room/fact-sheets/detail/taeniasis-cysticercosis

Mayo Clinic. (2023). Neurocysticercosis. https://www.mayoclinic.org