Eric York, a 37 year-old wildlife biologist at Arizona's Grand Canyon National Park was found deceased in his residence on the South Rim. York had became ill on October 30 and had called into work sick for a couple of days. His body was discovered on November 2nd.

Centers for Disease Control and Prevention (CDC) has confirmed plague as the cause of his death. this testing confirmed preliminary laboratory tests conducted by the Arizona Department of Health Services (ADHS) and the CDC.

Plague is a rare, but sometimes fatal, disease caused by the bacterium Yersinia pestis. It is primarily a disease of animals, but it can be transmitted to humans through the bites of rodent fleas or by direct contact with infected animals.

York grew up in Shelburne, Massachusetts and graduated from Mohawk Trail Regional High School. He earned an undergraduate degree from the University of Maine in 1992, and a master's from University of Massachusetts.

York was working with the cougar collaring program and had been at the Grand Canyon for about two years. Though the source of his infection is not certain, York most likely became infected with plague from a mountain lion he had skinned and preformed a necropsy on three days before he became ill. That cougar later tested positive for the same strain of plague.

York’s symptoms were consistent with pneumonic plague, the most serious but least common form of plague. In rare cases, pneumonic plague can spread person to person through aerosolized respiratory droplets (e.g. coughing, sneezing). However, according to the CDC, transmission of plague from person to person has not been observed in the United States since 1924.

Since pneumonic plague was initially suspected as a possible cause of York’s death, the National Park Service worked with the Grand Canyon Clinic to offer a seven-day course of prophylactic antibiotics to persons who had close contact (within six feet) with York while he was symptomatic. About 50 people have been contacted and are in the process of receiving medication. Close contacts of York have also been informed to watch for symptoms consistent with plague and to seek medical attention as soon as possible if symptoms develop. Symptoms of pneumonic plague include fever, headache, chest pain, cough, and bloody saliva. Early treatment with antibiotics is essential to surviving plague.

Plague is considered endemic in northern Arizona at elevations above 4,500 feet. While an average of one or two human cases of plague are reported each year in Arizona, there were no human cases reported from 2001 through 2006 in the state.

Increased plague activity in Arizona was reported in 2007 to public health officials: one human case, who survived, was reported in Apache County; prairie dog colony die-offs in two separate neighborhoods in Flagstaff (Coconino County) were confirmed to be from plague; and a domestic pet cat from north of Prescott (Yavapai County) was also documented as infected with plague.

York had direct contact with both wild rodents and mountain lions, which put him at a higher risk for plague than other park staff and the general public.

Persons living, working, or visiting areas where plague is known to be present can take the following precautions to reduce their risk of exposure:

• Do not handle sick or dead animals.
• Prevent pets from roaming loose.
• Control fleas on pets with flea collars or flea sprays routinely.
• Avoid exposure to rodent burrows and fleas and wild animals.
• Use insect repellant when visiting or working in areas where plague might be active or rodents might be present.
• Wear rubber gloves when cleaning or skinning wild animals.
• Domestic cats are susceptible to plague. Cat owners should take their ill cats to a veterinarian for evaluation.