Epidemiology

Trichinellosis is one of the most widespread human parasitoses, with approximately 11 million people at risk of acquiring it worldwide.[8] Throughout the world, the occurrence of trichinellosis is closely related to the dietary habits of affected humans. In countries with strict meat regulations and mandatory reporting of cases, the disease has become rare.[9]

In the US, an outbreak of trichinellosis was seen in 2022 following consumption of frozen meat of a black bear harvested in Canada.[10] Six cases were identified, of which two only consumed vegetables that were grilled with the meat.[10] Another outbreak was reported in North Carolina in 2023, wherein undercooked bear meat led to 10 cases of trichinellosis.[11]​​ 

Trichinellosis is relatively rare in Europe. In 2019, 12 western European countries (European Union/European Economic Area member states) reported 96 confirmed cases of trichinellosis, the majority of which were reported in Italy, Spain, and Bulgaria.[12] The overall EU/EEA notification rate was 0.02 cases per 100,000 population in 2019.[12] Trichinellosis has, however, re-emerged in eastern Europe, presumably as a consequence of the political and economic disruption of the 1990s.[13][14][15][16]

Trichinellosis is common in many Asian and South American countries, including Argentina, Chile, Mexico, Thailand, Indonesia, Laos, Malaysia, and Myanmar.[2] Epidemiologic data from China indicate that, during 2009-2020, human trichinellosis was principally localized in southwestern areas.[17] Eight outbreaks were reported, seven of which were caused by ingesting raw or semi-cooked pork. Two deaths were reported among 479 cases.[17] Human seroprevalence of swine anti-Trichinella IgG varied from 0% to 42% by province.[17] Poor pig rearing practices and consumption of improperly cooked or raw pig meat have been implicated.[17][18]

The prevalence of trichinellosis increases with advancing age, although there are no reported differences in the prevalence of the disease between men and women.[19] Certain religious groups (Muslims, Jews, Seventh Day Adventists, and Rastafarians) are at lower risk of developing trichinellosis as their religions forbid the consumption of pork.[20] Certain religious rites may increase the risk of acquiring trichinellosis, such as the Romanian thanksgiving custom of “pig’s alms” (consumption of different pork products, including raw meat).[21]

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