Cases of cat-associated human plague in the western US, 1977-1998

Exposure to cats infected with Yersinia pestis is a recently recognized ris k for human plague in the US. Twenty-three cases of cat-associated human pl ague (5 of which were fatal) occurred in 8 western states from 1977 through 1998, which represent 7.7% of the total 297 cases reported in that period. Bites, scratches, or other contact with infectious materials while handlin g infected cats resulted in 17 cases of bubonic plague, 1 case of primary s epticemic plague, and 5 cases of primary pneumonic plague. The 5 fatal case s were associated with misdiagnosis or delays in seeking treatment, which r esulted in overwhelming infection and various manifestations of the systemi c inflammatory response syndrome. Unlike infections acquired by flea bites, the occurrence of cat-associated human plague did not increase significant ly during summer months. Plague epizootics in rodents also were observed le ss frequently at exposure sites for cases of cat-associated human plague th an at exposure sites for other cases. The risk of cat-associated human plag ue is likely to increase as residential development continues in areas wher e plague foci exist in the western US. Enhanced awareness is needed for pro mpt diagnosis and treatment.