Changing face of paragonimiasis.

Abstract

[Extract] Paragonimus (lung fluke) species cause paragonimiasis, one of the neglected tropical diseases that many people might not be familiar with. Around 50 species have been named, some of which will prove not to be valid. Different species are known from Africa, the Americas, and Asia (especially Eastern and Southern Asia). As with many other trematodes, the life cycle is complex: cercariae develop in a freshwater snail, metacercariae develop in freshwater (sometimes brackish water) crabs or crayfish and adults develop in the lungs of mammals that eat crabs or crayfish. Typically, two adult worms live together in a cyst in the lungs and pass eggs out into bronchioles. Paragonimiasis is a zoonosis. Natural mammal hosts include members of the cat family, dog family, rodents, monkeys, marsupials (in the Americas), and more. Only a few species of Paragonimus infect humans. Some of these occupy cysts in human lungs, the usual site in their natural animal hosts, but other species end up in atypical sites such as the brain, where they can cause serious disease.