In January of 2016, doctors extracted a tapeworm that was nearly 20 feet long from a Chinese man. Shockingly, this is not the record for the longest worm to be pulled from a human; that distinction belongs to Sally Mae Wallace from whom doctors removed a tapeworm that was 37 feet in length.
Reportedly, the Chinese man was infected with the parasitic worm from all the raw beef he loved to consume. While this was an extreme case, human infections by these wriggly, squirmy parasites are not that uncommon, especially in developing parts of the world with poor sanitation. It's estimated that nearly 3 billion people are infected with the large roundworm, the hookworm or the whipworm. The pinworm is most common in the US and Europe, affecting mostly young children.
Worms generally have a bad reputation, as they can cause gastrointestinal problems and abnormal weight loss through parasitism. But in some instances, scientists have found that humans can be unaffected by the worm infections (commensalism relationship), or even benefited by the worms (symbiotic relationship). Watch the video to learn which worms hurt or help us along.