旋毛虫是线虫动物门毛形科的一种寄生虫。分布于全世界，流行于德国、意大利、奥地利、美国、中国等。见于啮齿类动物、猪、熊、人类中。旋毛虫通常也因常见于生猪肉产品中而被称为“猪肉虫”。

虫体细小，前端较细，后端稍粗。食道由单行细胞组成，占体长的1/3～1/2，后端接肠。肛门在虫体末端。生殖器为单管型。

Trichinella spiralis is a viviperous nematode parasite, occurring in rodents, pigs, horses, bears, and humans, and is responsible for the disease trichinosis. It is sometimes referred to as the "pork worm" due to it being found commonly in undercooked pork products.