ABSTRACT
Objective To investigate the space structure of plague natural foci in the area of Lantsang, Yellow and Yangtse River in Qinghai Province to provide references for making decisions to eontrol the occurrence of human plague. Methods Data was collected from the survey on natural foci and surveillance of plague from 1954 to 2006 and descriptive epidemiological method was used to analyze the data. Results Marmata hirnalayana and Microtus fuscua natural foci were known in Sanjiangyuan area. Callopsylla dolabris, Oropsylla silantiewi, Citellophilus sparsilis and Amphipsylla tuta were vectors; Microtus fuscus plague natural foci was in a range of about 9500 km2, distributing in Zhenqin Town, Chengduo County. Marmata himalayana plague natural foci distributed over 13 countries, a range nearly 107 000 km2. By the end of 2006, 450 strains of Yersinia pestis were detected and separated from 6 kinds of rodents, 6 kinds of carnivora, 3 kinds of artiodactyls and 9 insects vectors. Between 1960 and 2006, 238 cases and 134 deaths from plague were reported. Most human plague cases occurred in the months from May to November and usually presented as one of three primary forms-bubonic 17.23%(41/238), septicemic 16.81% (40/238), pneumonic 61.34% (146/238) and other types 4.62% (11/238). However, the first epidemic plague case was mainly the glandular plague. Conclusions Date suggested that plague is still a critical public health problem in Sanjiangyuan area, against which countermaeasure needs to be strengthened in the main epidemic areas. More scientific researches on plague should be carried out. Surveillance networks of reporting suspected plague have been established and reduce the number of human plague cases.