infectious diseases
Trichinosis
Pathophysiology of Trichinosis
TheTrichinellalife cycle is maintained by animals that are fed (eg, pigs, horses) or eat (eg, bears, foxes, boars) other animals whose striated muscles contain encysted infective larvae (eg, rodents). Humans become infected by eating raw, undercooked, or under-processed meat from infected animals, most commonly pigs, wild boar, or bear. Larvae excyst in the small bowel, penetrate the mucosa, and become adults in 6 to 8 days. Females are about 2.2 mm long, and males are about 1.2 mm long. Mature females release living larvae for 4 to 6 weeks and then die or are expelled. Newborn larvae migrate through the bloodstream and lymphatics but ultimately survive only within striated skeletal muscle cells. Larvae fully encyst in 1 to 2 months and remain viable for several years as intracellular parasites. Dead larvae eventually are resorbed or calcify. The cycle continues only if encysted larvae are ingested by another carnivore. 