Trichinellosis decreases but cases continue

Trichinellosis is a parasitic disease and infection which comes after eating raw or undercooked meat infected with Trichinella larvae.

Risk for Trichinella infection associated with commercial pork has decreased in the US since the 1940s, when data collection on trichinellosis cases began.

However, continued identification of cases related to pork and non-pork sources indicates public education about the parasite and the dangers of consuming raw or undercooked meat still is needed.

Trichinella was named number 16 on a list of foodborne parasites of greatest global concern in a report by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO​).

Surveillance finds decline​

During 1947–1951, when systematic tracking started, 400 cases with 10–15 trichinellosis-related deaths were reported each year.

Changes in domestic pork production and public health education on safe preparation have contributed to the reduction but consumption of wild game meat such as bear continues to be an important source of infection, said the Morbidity and Mortality Weekly Report​ (MMWR).

USDA recommends consumers of fresh ground pork and wild game cook the meat product to an internal temperature of 160°F (71°C).

Whole cuts of meat (excluding poultry and wild game) should be cooked to at least 145°F (63°C) then allowed to rest for three minutes before consuming.

The report authors noted two limitations: national surveillance is based on NNDSS, a passive surveillance system and many of the food exposure histories cannot be corroborated by laboratory or epidemiologic evidence and might represent only a best guess of what made the case-patients ill.

Four year period​

During 2008–2012, a total of 90 cases of trichinellosis, including five outbreaks, were reported to CDC from 24 states and the District of Columbia.

Pork products were associated with 22 (26%) cases, including 10 that were linked with commercial pork products, six with wild boar, and one with home-raised swine and five were unspecified.

Meats other than pork were associated with 45 cases, including 41 linked with bear meat, two with deer meat, and two with ground beef and the source for 17 (20%) cases was unknown.

Of the 51 patients with available information on how the meat product was cooked, 24 reported eating it raw or undercooked.

The confirmed or suspected source of infection was available for 67 (80%) cases.

Of those, 22 patients attributed illnesses to pork products, and 45 to non-pork products.

Among the 22 people who ate pork products, 10 got meat from a commercial source (six from supermarkets, two from butcher shops, and two from restaurants), six ate wild boar (from hunting), one consumed home-raised swine, and five had an unspecified product from an unknown source.

During 2008–2012, a median of 15 cases were reported annually to CDC, an increase from eight cases reported annually during 2002–2007.

The increase was attributable in part to the October 2008 outbreak in California, which accounted for 28 (33%) of cases.

Although incidence has decreased substantially since 1947, continued identification indicates the need for public education, said the report.

“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.”​