New records of sylvatic plague in Kansas

Sylvatic plague, or plague of wild rodents is caused by Yersinia pestis and entered California (USA) from Asia about 1899. Extensive sampling during t he 1930's and 1940's documented the spread of plague to approximately its c urrent distribution in North America. Records from the Centers for Disease Control and Prevention document plague in Kansas (USA) between 1945 and 195 0, but since then there has been no documentation of plague in the state. F ollowing a die-off of a black-tailed prairie dog (Cynomys ludovicianus) col ony on the Cimarron National Grassland, in the southwestern corner of Kansa s (37 degrees 10'N, 101 degrees 45'W), we sampled fleas from burrows in Jun e 1997, and tested them for Yersinia pestis. Twelve of 13 pools of Oropsyla hirsuta and one of two Pulex sp. were positive. A similar sample of fleas, from another colony where black-tailed prairie dogs were active at the tim e, yielded no positive fleas.