Trichinella is derived from the Greek words trichos (hair) and ella ( diminutive); spiralis means spiral. In 1835, Richard Owen (1804–1892) (Figure 1) and James Paget (1814–1899) (Figure 2) described a spiral worm (Trichina spiralis)‒lined sandy diaphragm of a cadaver. In 1895, Alcide Raillet (1852–1930) renamed it as Trichinella spiralis because Trichina was attributed to an insect in 1830. In 1859, Rudolf Virchow (1821–1902) described the life cycle. The genus includes many distinct species, several genotypes, and encapsulated and nonencapsulated clades based on the presence/absence of a collagen capsule (Figure 3).
The smallest, viviparous nematode or pig parasite has sylvatic and domestic cycles and causes trichinellosis or trichinosis. Transmission occurs through the consumption of meat infected with pathogenic cysts, encasing larvae (Figure 4). Human-to-human transmission has not been reported.