DPDx is an education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/capillaria/.
The nematode (roundworm) Capillaria philippinensis causes human intestinal capillariasis.
Typically,unembryonated eggs are passed in the human stool and become embryonated in the external environment ; after ingestion by freshwater fish, larvae hatch, penetrate theintestine, and migrate to the tissues . Ingestion of raw or undercooked fish results in infection of thehuman host. Humans are the only demonstrated hosts . The adults of Capillaria philippinensis (males: 2.3 to 3.2mm; females: 2.5 to 4.3 mm) reside in the human small intestine, where theyburrow in the mucosa . The females deposit unembryonated eggs. Some of thesebecome embryonated in the intestine, and release larvae that can causeautoinfection. This leads to hyperinfection (a massive number of adult worms) . Capillaria philippinesis is currently considered aparasite of fish eating birds, which seem to be the natural definitive host .
Capillaria philippinensis is endemic in the Philippines and also occurs in Thailand. Rare cases have been reported from other Asian countries, the Middle East, and Colombia.
Intestinal capillariasis (caused by C. philippinensis) manifests as abdominal pain and diarrhea, which, if untreated, may become severe because of autoinfection. A protein-losing enteropathy can develop which may result in cachexia and death.