Paragonimus is a lung fluke (flatworm) that infects the lungs of humans after eating an infected raw or undercooked crab or crayfish. Less frequent, but more serious cases of paragonimiasis occur when the parasite travels to the central nervous system instead of the lungs.

Although rare, paragonimiasis has been acquired in the United States, with multiple cases reported from the Midwest. Treatment for paragonimiasis is available from a physician after an accurate diagnosis is made.

Image: Left: Eggs of Paragonimus sp. taken from a lung biopsy stained with hematoxylin and eosin (H&E). These eggs measured 80-90 µm by 40-45 µm. The species was not identified in this case. Right: P. westermani adult, this approximately 1cm long fluke is viewed under magnification. Credit: DPDx