remarks: the world health organisation states that a rat-flea index greater than 1 represents an increased plague risk for humans if the plague bacillus was introduced into a territory.
注:世界衞生组织指出,鼠蚤指数高于1的地区如出现鼠疫桿菌,鼠疫传染给人类的风险便会增加。
methods the nocturnal rodents were captured in different habitat every month. the parasitic fleas were collected, dissected and observed, as well as do plague bacillus culture and serum detection.