An infestation by Paragonimus species, especially P. westermani
Paragonimiasis is caused by the species of the genus Paragonimus. One in particular is Paragonimus westermani, which is commonly known as oriental lung fluke. There are about thirty Paragonimus species known to cause paragonimiasis in humans.1 Paragonimus westermani is the most common causative agent. It is a species of the family Torglotrematidae of the class Trematoda. Trematodes, also called flukes, belong to the phylum of flatworms, Platyhelminthes.
Paragonimiasis is endemic especially in East and Southeast Asia (e.g. China, Japan, Vietnam, South Korea, Taiwan, Thailand, and the Philippines. It is estimated to affect 22 million people yearly around the world.2 Humans acquire paragonimiasis by ingesting raw or undercooked freshwater crabs or crayfishes. The common symptoms include abdominal pain, fever, cough, diarrhea, hepatosplenomegaly, eosinophilia, etc. Chronic infestation could lead to cough, hemoptysis, discolored sputum, and chest radiographic abnormalities.1
1 Centers for Disease Control and Prevention. (January 2013) Parasites - Paragonimiasis (also known as Paragonimus Infection). Retrieved from [].
2 Haswell-Elkins MR, Elkins DB (1998). "Lung and liver flukes". In Collier L, Balows A, Sussman M. Topley and Wilson's Microbiology and Microbial Infections 5 (9th ed.). New York: Oxford University Press. pp. 507–520.