This is part of our House MD Project series.
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The team rescues Rebecca after a collapse at the MRI machine. Photo by Fox broadcasting company. Credit: Alan Zenuk/FOX.
Danger level: High
What is it?
Neurocysticercosis is the most common disease caused by a parasite that infects the brain and spinal cord. It is caused by eating a type of worm.
Who gets it?
In the US, neurocysticercosis is mainly an immigrant disease. It’s more common among the Hispanic population and in the states of California, Texas and New Mexico. Other cases are caused by traveling to other parts of the world, or by eating infected foods (more on that later).
Throughout the world, the disease is most common in Central and South America, sub-Saharan Africa, and in some regions of the Far East.
What causes it?
Neurocysticercosis is caused by the ingestion of eggs of a certain type of worm, the pork tapeworm (which, in its scientific name is called Taenia solium).
How does this happen?
The tapeworm has a lifecycle, as can be seen in the drawing below:
People infected with the worm shed its eggs in their feces. In places of questionable hygiene, the infected feces can reach food or water sources (1). Once other people eat or drink infected food or drinks (7), the worm’s embryos hatch from the eggs in the small intestine, where they invade the intestines’ wall (8). From there they travel through the blood stream to the brain, muscles, under the skin, the eye, or almost any other place in the body (9). That leads to a dead-end, as you can see in the drawing.
If, on the other hand, a pig were to eat the contaminated food or water, and that pig is not cooked appropriately, a human eating that pig can be infected by the worm (4) (this is what happened on the House episode). The worm then attaches to the human’s small intestines (5), where they mature over a period of 2-4 months (6). They can live in the small intestines for years. Then the worm is spread in that human’s feces, and the cycle continues.
It’s important to understand that usually the worms we get from eating pork don’t reach our brains. Only when we eat eggs which can hatch as discussed above do we get neurocysticercosis. (However, if you do carry the worm and transmit it through your feces, and don’t wash your hands appropriately after visiting the toilet, you can transmit the eggs to yourself).
How does it feel?
As mentioned above, the worms can reach different organs in our body. What we feel depends on where they reach. Neurocysticercosis is the name of the disease that occurs when the worms reach the brain.
Once they reach the brain, any number of things can happen. The infected person can develop seizures. The pressure inside the brain can also rise, causing headache, nausea, vomiting, changes in vision, dizziness, problems walking, or confusion. The worms may also cause a stroke.
How is it discovered?
To find out if someone has neurocysticercosis, the eggs or worms have to be found. How can this be done? In one of 3 ways:
- Showing the worm in a sample taken from the body (muscle, for example).
- Showing the worm inside the eye, through equipment used by eye doctors.
- Showing the worm in images of the body (MRI or CT images), for example the brain – you can see an example of such an image below.
A brain infected with neurocysticercosis as seen in an MRI image.
There are other ways to discover the worm, such as blood tests or simply trying to treat the patient and seeing if the disease has improved.
How is it treated?
Once someone has a worm-infected brain, two things can be done to help them: Treating them with drugs that control seizures, and treating them with drugs that kill the worms (One such drug was used in House, called albendazole).
Steroids can also help in the treatment, since they can help reduce the brain swelling that may be caused by the disease. This actually happened in the show, when the patient was given steroids, which helped her, but only temporarily.
What happens after treatment?
Usually, the seizures associated with neurocysticercosis improve after treatment and can be stopped. In people with more severe complications, treatment may be less helpful.
The bottom line – How do I avoid it?
The CDC (Center for Disease Control) recommends you take the following measures to avoid having neurocysticercosis:
- Avoid eating raw or undercooked pork and other meats.
- Don’t eat meat of pigs that are likely to be infected with the tapeworm.
- Wash hands with soap and water after using the toilet and before handling food, especially when traveling in developing countries.
- Wash and peel all raw vegetables and fruits before eating. Avoid food that may be contaminated with feces.
- Drink only bottled or boiled (1 minute) water or carbonated (bubbly) drinks in cans or bottles. Do not drink fountain drinks or any drinks with ice cubes. Another way to make water safe is by filtering it through an “absolute 1 micron or less” filter AND dissolving iodine tablets in the filtered water. “Absolute 1 micron” filters can be found in camping/outdoor supply stores.
What next?
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