The epidemiology of human trichinellosis in China during 2004-2009

The endemic foci of human trichinellosis are mainly located in southwestern China. Seroepidemiological surveys of Trichinella spiralis infection in humans were carried out in 10 out of 34 Provinces/Autonomous Regions/Municipals (P/A/M) of China during 2004-2009. The overall seroprevalence was 3.19% (3198/100,282). The highest seroprevalences were mainly located in western China: 8.43% in Yunnan, 6.37% in Inner Mongolia and 5.35% in Sichuan. The seroprevalence of Trichinella infection in humans was related to the habit of eating meat and differed among nationalities. From 2004 to 2009, 15 outbreaks of human trichinellosis, consisting of 1387 cases and four deaths, were reported in the three southwestern-most P/A of China (nine outbreaks in Yunnan, two in Sichuan and four in Tibet), where ethnic groups routinely eat raw meat. Pork is the predominant source of outbreaks of human trichinellosis in China. Out of 15 outbreaks, 12 (85.71%) were caused by eating raw or undercooked pork, and 2 (13.33%) resulted from the consumption of raw wild boar, suggesting the significance of game meat as a source of infection for human trichinellosis. An outbreak of imported trichinellosis involving 49 cases in Yunnan during December 2006 from Laos is the first recorded outbreak of imported trichinellosis in China, but the source of that outbreak could not be identified. The mandatory inspection of pork should be further strengthened in southwestern China.