Anthelmintics are a group of antiparasitic antibiotics that treat infections by parasitic worms or helminths.
They are roughly divided into two groups: vermifuges, which stun helminths; and vermicides, which kill them.
Now “helminth” is not a term based on taxonomy; instead, it’s a practical term used for many multicellular, worm-like parasites that can infect humans. These include cestodes, trematodes, and nematodes.
Cestodes are tapeworms that can grow to prodigious size, some even reaching over 20 feet, or 7 meters!
Species like Taenia solium, or pork tapeworm, and Taenia saginata, or beef tapeworm, are transmitted via undercooked pork and beef.
Once eaten, they hang out in the small intestine, living off of the nutrient-rich fluid around them.
They are also hermaphrodites and can lay over 50,000 eggs in their lifetime, so you’re never lonely when you have tapeworms!
The disease itself, taeniasis, can be asymptomatic or it can cause GI symptoms, like abdominal pain, nausea, diarrhea, and weight loss.
However, if the eggs of the Taenia solium found in human feces is ingested, it could cause cysticercosis. This is where newly hatched larvae burrow into different parts of the body like the eyes, which can cause blindness; and also the brain, which can lead to seizures and death.
Next are trematodes, which are more commonly known as flukes.
Common species that infect humans include Schistosoma species, or blood flukes, that cause schistosomiasis, also called snail fever.
These parasites live inside freshwater snails and pop out as free swimming larva that search for unsuspecting swimmers, and penetrate the skin through hair follicles to make their way into capillary beds, where they feed on blood.
Liver flukes like Clonorchis and Opisthorchis species also use snails as a host, but their larvae invade fish, that are then eaten by humans.
Once ingested, the fluke burrows through the intestinal wall and head straight for the liver and bile duct, where they feed on bile.
Nematodes or roundworms are a particularly diverse bunch. Most infections start when a person eats or drinks something contaminated with nematode eggs, which are transmitted through human feces. This is why it’s important to wash your hands after using the bathroom before eating!
The eggs hatch into larvae in the small intestine and cause GI symptoms like malabsorption, diarrhea, and abdominal pain.