ASCP Parasitology Practice Exam

Paragonimus westermanii is classified as a tissue fluke, which is a type of trematode (flatworm). This organism resides in the lungs of its definitive hosts, typically humans and other mammals. The life cycle of Paragonimus westermanii includes multiple stages, starting from eggs laid in the lungs, which are then coughed up and either swallowed or expelled into water sources. From there, the eggs hatch into larvae that infect snails, and subsequently, these larvae can infect crustaceans like crabs. Ultimately, when humans consume undercooked crustaceans, they can get infected by the parasite.

Being a tissue fluke signifies that it primarily invades and resides within bodily tissues - in this case, lung tissue - which can lead to various health issues like lung infections or other respiratory problems. This characteristic distinguishes it from other types of parasitic organisms like roundworms, which are nematodes that typically inhabit the gastrointestinal tract, tapeworms, which are also flatworms but adopt a different lifestyle primarily in the intestine, and protozoans, which are single-celled organisms that usually have different life cycles and methods of infection. Understanding the classification of Paragonimus westermanii helps in recognizing its