Trichinella spiralis

Trichinella spiralis is a parasitic roundworm that causes trichinellosis (trichinosis) when people eat undercooked meat, most often pork or wild game, containing its encysted larvae. It is unusual in completing both larval and adult stages in a single host.

🧬 Field Guide Specimen: Open Pork Muscle Worm in the CRV Science Field Guide to log the specimen, see its place among the Ecdysozoa lineages in the Cladogram Explorer, and test your recall in the Red List conservation game.

After meat is eaten, the larvae are freed by stomach acid, mature into adults in the intestine and mate. The females release newborn larvae, which travel in blood to skeletal muscle, where they invade cells and coil into cysts, turning the muscle cell into a "nurse cell".

Intestinal infection can cause diarrhea, and muscle invasion brings fever, muscle pain and facial swelling. The parasite was first seen in human muscle by James Paget in London in 1835.

Cooking meat to an internal temperature of about 71 degrees Celsius kills the larvae. Improved pig feeding practices and inspection have made the disease rare in many countries, but wild game such as bear remains a source.

• Cellular differentiation — host cell reprogramming
• Immunology — immune responses to helminths