Trichinella spiralis is a viviparous[1] nematode parasite, occurring in rodents, pigs, bears, hyenas and humans, and is responsible for the disease trichinosis.

Each adult female produces batches of live larvae, which bore through the intestinal wall, enters the blood (to feed on it) and lymphatic system, and are carried to striated muscle.

The larvae gain access to the circulation and migrate around the body of the host, in search of a muscle cell in which to encyst.

In some cases, accidental migration to specific organ tissues can cause myocarditis and encephalitis that can result in death.

[5] The hypoxic environment stimulates muscle cells in the surrounding tissue to upregulate and secrete angiogenic cytokines, such as vascular endothelial growth factor (VEGF).

The migration of adult worms in the intestinal epithelium can cause traumatic damage to the host tissue, and the waste products they excrete can provoke an immunological reaction.

Ten days following ingestion, intense muscular pain, difficulty breathing, weakening of pulse and blood pressure, heart damage, and various nervous disorders may occur, eventually leading to death due to heart failure, respiratory complications, or kidney malfunction, all due to larval migration.

In the United States, the national trichinellosis surveillance system has documented a steady decline in the reported incidence of this disease.

[9] In the United States, Congress passed the Federal Swine Health Protection Act, restricting the use of uncooked garbage as feed stock for pigs, and creating a voluntary Trichinae Herd Certification Program.

[citation needed] Through the U.S. Code of Federal Regulations, the USDA has created guidelines for specific cooking temperatures and times, freezing temperatures and times, and curing methods for processed pork products to reduce the risk of human infection from Trichinella contaminated meat.

At that time, the parasite was considered endemic in Japan and China, while Korea had recently reported its first human cases of trichinosis.

[8] Post-slaughter human exposure is also preventable by educating consumers on simple steps that can be taken to kill any larvae that can potentially be in meat bought at the local supermarket.

Cooking pork products to a minimum internal temperature of 160 °F (72 °C) for 3 minutes will kill most species, and is the best way to ensure the meat is safe to eat.

[12] It was reported in 2009 that political and economic changes had caused an increase in the prevalence and incidence rates of this parasite in many former eastern European countries due to weakened veterinary control on susceptible animals.