Capillaria obsignata
Capillaria obsignata (aka Capillaria columbae) is a nematode that lives in chickens and is the only common species for capillariasis in commercial chickens. The adult male is about 9.5-11.5 mm in length and the female is about 10.5-14.5 mm. The ova are operculated and the the larvae stay in the egg until it is ingested. They have a direct life cycle (monoxenous). The larvae reside against mucosa of the duodenum and maintain a prepatency of 3 weeks. They are found only in older chickens (not broilers). Pathogenesis and pathology of C. obsignata includes the following:
Enteritis with some hemorrhaging
Diarrhea
Loss of weight, droopiness, weakness, and mortality (lowered feed efficiency)
Villus atrophy and rejection is probable (thigmokinetic effect)
Capillaria annulata (aka Capillaria contorta) is similar to C. obsignata but the males are up to 2.5 cm long and the females can be up to 6 cm making them significantly larger than C. obsignata. One major difference between the two is that C. annulata has an indirect life cycle that usually involves some arthropod as an intermediate host. Also, the adults are found in the wall of the crop and are most commonly found at game farms in quail and pheasant.
