Raw meats may also contain harmful parasites. As with bacteria, these parasites are destroyed during the heat processing of cooking meat or manufacturing pet foods. Some raw diet recipes call for freezing meat before serving it, which greatly reduces (but does not necessarily eliminate) extant parasites. According to a former European Union directive, freezing fish at -20 °C (-4 °F) for 24 hours kills parasites. The U.S. Food and Drug Administration (FDA) recommends freezing at -35 °C (-31 °F) for 15 hours, or at -20 °C (-4 °F) for 7 days. The most common parasites in fish are roundworms from the family Anisakidae and fish tapeworm. While freezing pork at -15 °C (5 °F) for 20 days will kill any "Trichinella spiralis" worm, trichinosis is rare in countries with well established meat inspection programs, with cases of trichinosis in humans in the United States mostly coming from consumption of raw or undercooked wild game. Trichinella species in wildlife are resistant to freezing. In dogs and cats symptoms of trichinellosis would include mild gastrointestinal upset (vomiting and diarrhea) and in rare cases, muscle pain and muscle stiffness.