New trends and clinical patterns of human trichinellosis in Russia at the beginning of the XXI century.

Official national statistics show a gradual decline in the incidence of trichinellosis in Russia from 971 cases in 1996 to 527 cases in 2002. Of the total 864 cases involved in 47 trichinellosis outbreaks during 1998--2002, only 35.8% were due to infected pork compared to 80% in 1995--1996. Other important sources were wild animals, such as bear (Ursus arctos) (39.5%), badger (Meles meles) (10.6%), and dog meat (11.9%). Children composed 15.9% of all cases. Overall, 81.0% of pork-cases occurred in the European part of the country, and 89.4% of bear-meat cases were from the Asian region where most of the badger and dog-meat cases also originated. The percent of clinically severe cases of disease derived from pork and from bear meat was 7.7% and 7.9%, respectively; the frequency of moderate cases from pork was significantly higher than from bear meat. Clinically severe cases from badger and dog meat were 1.1% and 1.9%, respectively, where the number of clinically moderate cases from badger meat was significantly larger than that from dog meat. A disturbing trend is the 52.3% of trichinellosis cases during 1998--2002 in Russia that were derived from wild animal meat, especially the clinically severe cases occurring among the aboriginal Siberian population. The contributing factors to the slow decline in trichinellosis incidence in Russia and to the increase in percentage of cases originating from wild animal meat are the distribution and consumption of veterinary-uncontrolled pork, poaching and distribution of wild animal meat, and the neglect of medical and civil regulations. These trends should be seriously evaluated by the institutions of health, education, and by the veterinary service.