Capillaria philippinensis

Did You Know?

• Early diagnosis is beneficial to prevent the number of worms from increasing.
• C. philippinensis eggs have nonprotruding polar plugs and are slightly smaller than Trichuris trichiura eggs.
• Treatment includes mebendazole 200 mg twice daily for 20 days or until symptoms subside and eggs are absent.

Discovery and nomenclature

Between the first case reported in 1964 and the end of 1967, over 1000 cases were documented in and around Northern Luzon, particularly at Tagudin, Ilocos Sur, including 77 deaths. Locals hired witch doctors to exorcise a curse believed placed by the river god. In 1968, the cause was identified as Capillaria philippinensis. Adults are very small: males 1.5–3.9 mm long, females 2.3–5.3 mm long. Eggs are peanut-shaped with a striated shell, measuring 36–45 μm by 20 μm. The species has been transferred to the genera Aonchotheca and Paracapillaria, but is almost universally referred to as Capillaria philippinensis in current medical literature.

Hosts and life cycle

The complete life cycle may be indirect (involving an intermediate host) or direct. Experimental infestations of several fishes, including Cyprinus carpio and Puntius gonionotus, with eggs yielded infective larvae. Infestations of birds such as Amaurornis phoenicurus and Nycticorax nycticorax with larvae yielded mature adults. Feeding a few dozen larvae from fish intestines to Mongolian gerbils or monkeys led to thousands of adult worms through autoinfection, where offspring reinfest the same host. Both oviparous and larviparous adult females were found in gerbils and some birds. Monkeys never developed clinical symptoms; only gerbils developed severe symptoms and died.