Eric York, a 37 year old wildlife biologist who worked at the Grand Canyon National Park who was found dead at his home on the South Rim of the Canyon in Arizona on November 2nd, probably died of the plague caught while carrying out an autopsy on a mountain lion that had probably died of the disease a week earlier.

Plague, due to the bacterium Yersinia pestis, was confirmed as the likely cause of death following preliminary laboratory tests at the Arizona Department of Health Services (ADHS) and the Centers for Disease Control and Prevention (CDC).

York had been treated at a local clinic for flu like symptoms that started three days after he did the autopsy, but nothing more serious than that was diagnosed at the time. When he was found dead health officials suspected either plague or hantavirus that causes a type of hemorrhagic fever, and immediately tracked down 49 people who had been in recent contact with him so they could have aggressive antibiotic treatment. None of them has become ill.

Plague is primarily a disease of animals and rarely infects humans, who can catch it from being bitten by rodent fleas or, as is suspected in the case of York, from direct contact with infected animals. York' symptoms were similar to those of pneumonic plague, the most serious, but least common form of plague.

Plague can be passed on from one human to another, and from animals to humans, through coughing and sneezing, which thrusts infected droplets into the air that is then breathed in by others. However, according to the CDC, human to human infection is rare, and their records show the last time this happened in the US was in 1924.

Symptoms of pneumonic plague include: high fever, chills, nausea, chest pain, cough, headache, and blood in the saliva. Symptoms are often accompanied by a painful, enlarged lymph node in the groin or armpit. If treated early with antibiotics, the chances of survival are very high.

Anyone who has these symptoms, particularly if they have been exposed to fleas, sick cats, rodents or rabbits in areas where plague may be active, should seek medical attention immediately.

Plague is considered endemic high in the mountains of northern Arizona (above 4,500 feet). 48 cases of plague have been reported in the state since 1977, eight of which were fatal. Not one was reported between 2001 and 2007, which officials put down to drought conditions and high summer temperatures.

In September 2007, Arizona health officials released news of the state's first human infection since 2000, a woman in Apache County, who became ill following a flea bite at her home in the northern part of the state. She was given antibiotics and is now recovering, they said.

Craig Levy, head of Arizona's Vector Borne and Zoonotic Disease Program, said at the time that:

"The recent appearance of plague activity in two northern counties has us concerned that we may see plague in other areas as well."

Animal cases of plague in Arizona in 2007 include prairie dog colony die-offs in two separate neighbourhoods in Flagstaff in Coconino County, and a pet cat in Prescott in Yavapai County.

Arizona state health officials warned campers, hunters, hikers and others who live at 4,500 feet or higher or are visiting the area, to take the following precautions to avoid being exposed to the plague:

-Do not handle sick or dead animals.

-Don't go near rodent burrows.

-Avoid exposure to fleas.

-Stop your dog or cat from roaming as they can bring home plague infected fleas.

-Use flea control products on your dog or cat, ask your veterinarian about the best ones.

-Wear protective gloves when cleaining or skinning wild animals, for instance for cooking.

-If cooking game meat, do so at 180 degrees, until the juices run clear.

-If you get start getting symptoms like those listed above, within 6 days of a potential exposure, seek medical help at once.

-If your cat falls ill, get it checked by a veterinarian.

For more information call the Grand Canyon National Park Incident Information Center at (928) 638-7922 or (928) 638-7688.