Eating raw potatoes does not cause worms, although it is not a particularly good practice for humans. Raw potatoes have a high concentration of alkaloids, which are broken down during the cooking process. Exposure to high levels of alkaloids can have adverse effects such as diarrhea, vomiting, headaches and hallucinations.
Eating raw potatoes also exposes the human body to potentially harmful bacteria that are killed by heat during the cooking process. Because potatoes grow in the ground, they can be contaminated with listeria, E coli or salmonella from the soil or water and should be cooked to avoid illness. Raw potatoes are also much harder for the body to digest and can cause undue stress on the liver.