Experimental infection of Trichinella spiralis in 1-day-old chickens showed that most worms were rapidly expelled from the intestine but those that remained developed to maturity and produced newborn larvae. These newborn larvae were found in the chicken muscles between days 9-21 postinfection (PI) but they showed little or no development. No larvae were detected in the muscles at day 25 PI and thereafter. Although the newborn larvae were able to penetrate the chicken muscle fibers, they were unable to grow normally, which resulted in their death and degeneration. The fact that the newborn larvae, which were shed in vitro by female worms retrieved from the chicken intestine, were able to develop into mature larvae when injected intravenously into mice indicated that the death of the newborn larvae in the chicken muscles was not due to any inherent defect of the larvae
