The incidence of plague appears to be cyclical, apparently linked to the high-moisture, milder winters typical of El Nino years that cause rodents to thrive, Ettestad said. This year, the rodent population in New Mexico is estimated at 10 to 20 times higher than last year, when no one in the state caught plague. Believed to have evolved in central Asia, plague is new to the United States. It arrived about 1900 in San Francisco aboard trading ships from China and spread from urban rats into the wild rodent population of the West. There were outbreaks in ports along the Gulf of Mexico, but it never got established in the native rodents there, according to the CDC's Gage.
Cats are more susceptible to plague than dogs and get sicker.
Listlessness and not eating are clues that a cat is ill. Plague also can be contracted by handling infected animals. Hunters, for example, are at risk if they don't wear gloves while skinning animals. Esther Morrison gives her cat anti-flea treatment regularly and sprays her woodpiles. She says if she were to get sick and suspected plague, she would be aggressive about demanding the appropriate treatment.