When you think of the world’s most dangerous animals, chances are you picture creatures like lions, snakes, and sharks. And why wouldn’t you? All three are known for being exceedingly dangerous to humans, and people do lose their lives to these animals in regular numbers every year.
But, what if you found out one of the planet’s deadliest creatures actually lived in bodies of fresh water and could fit in the palm of your hand? It’d be a difficult thing to believe, but it’s completely true.
Believe it or not, one of the deadliest animals on Earth is the simple freshwater snail. These miniature mollusks might appear harmless, but once you learn about the brain-controlling “zombie” parasite many of them carry, you may never take a dip in a lake again!
Most people would probably put animals like lions, snakes, and sharks at the top of any list of deadliest animals. But what most of them don’t know is there’s an even more dangerous animal that lives in fresh water—and it fits in the palm of your hand.
The freshwater snail is considered to be one of the world’s deadliest creatures. These tiny mollusks can be found in lakes and ponds all over the world, and many of them carry a deadly transmittable parasite that kills over 200,000 people a year. That’s more than any predatory mammal!
Many freshwater snails carry a harmful parasite called cercariae that causes the disease schistosomiasis, or “snail fever.” The snails release the parasite in its larval form into the water, and it penetrates the skin of anyone who comes in contact with it.
Here is a simple illustration of how the cercariae larva is transferred from the snail to the host, and then eventually back to the snail again. The parasite actually takes over the brain functions of the snails, essentially turning them into controlled “zombies.” How crazy is that?
The parasite uses this mind-control technique to prolong its life for as long as it can. Once it enters a snail, it has full control of their body. It uses them to locate a new host so it can lay more eggs and multiply while feeding off the nutrients provided by its victim.
Suzanne Sokolow, a disease ecologist, spoke about schistosomiasis. She said, “Schistosomiasis eggs can lodge in different tissues and cause severe symptoms ranging from anemia and fatigue, all the way to various severe symptoms, and even death in about 10 percent of chronic cases.”
Schistosomiasis is most prevalent in poor countries that don’t have the same strict water sanitation laws as many other places do. It’s especially rampant in many parts of Africa. The water isn’t safe enough to drink or bathe in, but because many people live in extreme poverty, they do it anyway.
Another way these deadly parasites enter into human bodies is from contaminated snails that are used for food. Large batches of these freshwater mollusks are gathered for meals, but they aren’t cleaned thoroughly, and the parasites enjoy an easy entry into their new host.
The symptoms of schistosomiasis are extremely unpleasant. The host’s skin will break out in itchy red bumps at first, and depending on where the parasite laid its eggs, they could experience side effects like severe abdominal pain, diarrhea, and traces of blood in urine and stool.
It’s hard to believe that something as small and seemingly harmless as a freshwater snail can have such a deadly impact on so many people worldwide. There are treatments for schistosomiasis, but experts say the most effective way to combat this problem would be a call for better sanitation regulations in the affected areas. Until they do get those regulations, people should be extra careful.
Yikes! The next time you head to a pond or a lake to take a dip, definitely keep an eye out for these little guys.
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