[Analysis of human plague episodes in Qinghai from 1958 to 1991].

One hundred and sixty four episodes of human plague including a total of 387 cases occurred in Qinghai Province from 1958 to 1991. The average yearly number of episodes of plague and case fatality rate were 5 including 11.7 cases and 54.26%, respectively. The sources of infection were Himalayan Marmota in 73.17% and non-rodent animal hosts in 15.85% Pneumonic type, simple bubonic type and septicemic type of plague accounted for 57.88%, 23.26% and 16.27%, respectively. However, the first case in each episode manifesting as bubonic type of plague accounted for 87.80%. Cases of plague appeared in April, then its number increased with months, and reached the peak in August. A few cases could still be seen in December.