4. Blood flukes (via freshwater snails)

You know the animal is bad if it’s got “blood” in the name. Blood flukes are a type of parasitic worm, called schistosomes, that cause the disease schistosomiasis. They live and grow in freshwater snails, but then move to humans when people come in contact with contaminated water. They actually get into humans through the skin, instead of open parts like the mouth.

In humans, they live in the liver, veins, and urinary tract. The worms lay eggs inside people, which are then spread through human excrement. This disease is mostly in Africa, but also in other poor communities in places like South America and the Middle East. There are treatments for it, but not everyone has access to them.