Trichinosis

Trichinosis, or trichinellosis, is a zoonotic parasitic disease caused by nematodes of the genus Trichinella, most commonly Trichinella spiralis. Humans acquire infection by eating undercooked or raw meat containing encysted larvae, especially pork and game such as bear, boar, or walrus.

After ingestion, larvae are released in the small intestine, where they mature into adults. Female worms release new larvae that migrate through the bloodstream to striated muscles, where they encyst in muscle fibers. The disease often has two phases: a gastrointestinal phase with abdominal pain, diarrhea, and vomiting occurring within days of exposure, and a second phase days to weeks later characterized by myalgia, fever, periorbital edema, weakness, and sometimes headache. Severe infections may involve myocarditis, pneumonitis, or encephalitis.

Diagnosis relies on exposure history and laboratory evidence. Eosinophilia is common; elevated creatine kinase and LDH may occur. Serologic tests (ELISA) can detect antibodies within 1–2 weeks but may remain positive for months. Muscle biopsy can show encysted larvae but is not routinely required.

Treatment depends on severity. Mild cases may improve with time; antihelminthic therapy such as albendazole or mebendazole is used to eradicate intestinal and tissue stages. Corticosteroids may be added in cases with significant inflammatory symptoms. Supportive care is important for complications.

Prevention focuses on proper cooking of meat and game: pork should be cooked to safe internal temperatures and ground meats thoroughly cooked; freezing is not reliably effective against all Trichinella species. Public health measures and surveillance reduce incidence in developed countries; rates are higher in areas with limited meat inspection and in wildlife hunters.

History: The parasite is named Trichinella spiralis; human trichinosis has been recognized since the 19th century.