The parasitic disease, Trichinellosis follows consumption of raw or undercooked meat infected with Trichinella larvae. It has been a nationally notifiable disease in the United States since 1966 and is reportable in 48 states, New York City, and the District of Columbia.

Trichinella spiralis parasite
Trichinella spiralis cysts

According to researchers with the Division of Parasitic Diseases and Malaria, Center for Global Health, a total of 84 confirmed trichinellosis cases, including five outbreaks, which were reported from four states (Alaska, California, Illinois, and Minnesota) that comprised 40 cases from 2008-2012 were analyzed for the report published in the latest MMWR. Bear meat was implicated in three of the five outbreaks.

During 2008–2012, the mean annual incidence of trichinellosis in the United States was 0.1 cases per 1 million population, with a median of 15 cases per year. Pork products were associated with 22 (26%) cases, including 10 (45%) that were linked with commercial pork products, six (27%) that were linked with wild boar, and one (5%) that was linked with home-raised swine; five (23%) were unspecified. Meats other than pork were associated with 45 (54%) cases, including 41 (91%) that were linked with bear meat, two (4%) that were linked with deer meat, and two (4%) that were linked with ground beef. The source for 17 (20%) cases was unknown. Of the 51 patients for whom information was reported on the manner in which the meat product was cooked, 24 (47%) reported eating raw or undercooked meat.

According to the report, during 1947–1951, when systematic tracking of trichinellosis cases began in the United States, approximately 400 cases with 10–15 trichinellosis-related deaths were reported each year. This number declined to a median annual incidence of eight cases (range: 5–15) during 2002–2007, with no reported deaths.

Historically, 60%–88% of infections in the United States were the result of ingesting raw or undercooked Trichinella-infected pork. However, measures taken by the U.S. pork industry many decades ago to improve the health of farm-raised hogs have made Trichinella infections in U.S. swine rare. The consumption of meat from Trichinella-infected wildlife, including wild boar, are now implicated in a greater proportion of cases.

The report concludes although the incidence of trichinellosis has decreased substantially since 1947, the continued identification of trichinellosis cases related to commercial pork consumption, infections from sylvatic sources such as bear meat, and the reported histories of consumption of raw or undercooked meat indicate the continuing need for public education about trichinellosis.

Persons receiving permits to hunt bear, wild boar, or other potential Trichinella hosts should be informed about the risk for trichinellosis and receive instruction regarding proper food safety practices. Consumers of pork and game meat should follow the recommended cooking and freezing methods to inactivate Trichinella larvae and follow good hygienic practices with raw meat. In addition, the public should receive ongoing education about prevention methods, with additional communication efforts during an outbreak.