ABSTRACT
Objective To master of the characteristics of development and variation in plague natural foci of Marmota sibirica, and to analyze the plague monitoring results from 2004 to 2008. Methods From May to September every year, we monitored plague in Manzhouli, Chenbaerhuqi, Xinbaerhuzuoqi, Xinbaerhuyouqi,Ewenkeqi and Yakeshi city. The monitored area was 20 000 - 40 000 hm2 in every county. The density of Marmota,ground squirrel and moonlighting rats was surveyed by path method, one-day bow-clip method and a clamp was placed every five meters, respectively. The classification and identification of ectoparasite fleas were done by using low power lens. The fleas in the ground squirrel hole were collected by flannel rubber stick, then classified and identified. According to National Standard of Plague Diagnostic Criteria(GB 15991-1995), the collected rats and fleas were detected by isolation and cultured Yersinia pestis, the serums of collected rats were tested by indirect hemagglutination test. Results In five years, the density of Marmota and ground squirrel was 0.010/hm2 and 0.602/hm2, respectively. The capture rate of moonlighting rats was 2.69％ (258/9600). The flea infection rate of Marmota was 17.54％(10/57) and the fleas index was 2.54. The fleas infection rate of ground squirrel was 28.40％(213/750) and the fleas index was 1.01. Flea infection rat of ground squirrel hole was 5.60％(46/822) and the fleas index was 0.17. The total number of various hosts of Yersinia pestis detected was 1351, the groups number of the variety of cultured fleas was 127, and the pathogen test results were negative. The number of serum tested was 1064, positive number was 43, and the detection rate was 4.04％(43/1064). The highest positive titer was 1 : 1280. Other than 2006, the remaining four years were found positive for blood clotting material; positive serum was found in a total of three regions, they were Manzhouli, Xinbaerhuzuoqi, and Xinbaerhuyouqi; and 30, 12 and 1 copies of hemagglutination-positive sera were detected. Conclusions The epidemic of plague natural foci of Marmota sibirica is in a active state, and gradually expands the scope. We must continue to strengthen the inspection of the bacteria, bearing in mind the replacement of the region's main host, make every effort to prevent and control of human plague.