x Parasites:Parasites(parasitic worms)of public health importance are the beef and pork tapeworms(Taenia saginata牛肉绦虫and Taenia solium猪肉绦虫， respectively)and the roundworm that causes trichinosis(Trichinella spiralis猪旋毛虫). Viruses and Protozoa:Viruses can cause diseases such as hepatitis and polio and protozoa can cause diseases such as toxoplasmosis弓形虫病and cryptosporidiosis隐孢子虫病in humans. Parasites: Parasites (parasitic worms) of public health importance are the beef and pork tapeworms (Taenia saginata 牛肉绦虫 and Taenia solium 猪肉绦虫, respectively) and the roundworm that causes trichinosis (Trichinella spiralis猪旋毛虫).  Viruses and Protozoa: Viruses can cause diseases such as hepatitis and polio and protozoa can cause diseases such as toxoplasmosis 弓形虫病 and cryptosporidiosis 隐孢子虫病 in humans