Paragonimiasis is a food-borne parasitic disease caused by several species of lung flukes belonging to genus Paragonimus.

Paragonimiasis is easily mistaken for other diseases with which it shares clinical symptoms, such as tuberculosis and lung cancer.

[9] These trematodes have a very complex life cycle with seven distinct phases involving intermediate hosts and humans.

These young worms penetrate intestinal wall, peritoneum, the diaphragm and the pleura where they finally reach the lungs.

[5] In the external environment, the eggs remain unembryonated until ideal conditions of temperature and humidity are encountered.

As the egg shells disintegrate, the motile miracidia hatch and swim to seek the first intermediate host, a snail, and penetrate its soft tissues.

Freshwater crab species of genera Potamiscus, Potamon, Paratelphusa, Eriocheir, Geothelphusa, Barytelphusa, crayfish species of genus Camberoides and shrimps of genera Acrohrachium and Caridina commonly serve as the secondary intermediate hosts.

The secondary intermediate hosts are infected either by directly eating the snail or penetration of the body by free-swimming cercariae.

[11] Human infection with P. westermani—the best understood species—occurs by eating inadequately cooked or pickled crab or crayfish that harbour metacercariae of the parasite.

[7] Unlike most other trematodes, after they migrate from the intestine, they remain in the peritoneal cavity until they find a suitable partner.

However, when this takes place completion of the life cycles is not achieved, because the eggs laid cannot exit these sites.

[7] Just as the species names imply, paragonimiasis is more prominent in Asians, Africans and Hispanics because of their habitats and cultures.

[10] Paragonimiasis causes pneumonia with characteristic symptoms including prolonged cough, chest pain, shortness of breath, and hemoptysis.

[4] The acute phase (invasion and migration) may be marked by diarrhea, abdominal pain, fever, cough, urticaria, hepatosplenomegaly, pulmonary abnormalities, and eosinophilia.

During the chronic phase, pulmonary manifestations include cough, expectoration of discolored sputum containing clumps of eggs,[7] hemoptysis, and chest radiographic abnormalities.

[13] Diagnosis is based on microscopic demonstration of eggs in stool or sputum, but these are not present until 2 to 3 months after infection.

[4] A rapid antibody detection kit, dot-immunogold filtration assay (DIGFA), was developed for P. wertermani in China in 2005.