title: Evidence, nature, and implications of the constitutive resistance to Trichinella spiralis in gallinaceous birds.
abstract: White Leghorn chickens and mice were orally infected with Trichinella spiralis larvae and their digestive tracts were examined for parasites at postinfection hours (PIH) 5 and 10, and at postinfection days (PID) 1, 2, 4, 6, and 8. Evacuated feces were examined at PIH 5 and 10 and at PID 1, and blood was examined at PID 4, 6, and 8. With the exception of trichinae in the digestive tract (9 at PIH 5 and 2 at PIH 10), parasites were not recovered from chickens. All mice had abundant parasites in the digestive tract and a few parasites in the blood; however, parasites were not found in blood or feces at PID 4. In vitro incubation of infective larvae (4 hours at 37 C) in an extract of glandular stomach or in a combination of extracts from the small intestine, pancreas, and bile of chickens caused visible alterations in 42% to 64% of the larvae and caused total loss of larval infectivity for mice. Sequential incubation in both fluids caused damage in 91% to 97% of the larvae. The same experiments with mouse extracts caused damage in only 8% to 26% of the larvae and infectivity of the larvae for mice was not reduced noticeably. Digestion of infective T spiralis larvae is an important constitutive mechanism of resistance in chickens that probably precludes the transmission of the infection by gallinaceous birds in nature.
mesh_terms: D000818:Animals; D002645:Chickens / Q000469:parasitology*; D004064:Digestive System / Q000469:parasitology; D007113:Immunity, Innate; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D011200:Poultry; D011201:Poultry Diseases / Q000469:parasitology* / Q000635:transmission; D012376:Rodent Diseases / Q000469:parasitology; D014235:Trichinellosis / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*