(photo by Carl Auer)
The Apache County Health Department recently notified the public about a new prairie dog die-off in Concho.
A previous die-off was reported in early July.
A notice posted on the Apache County website on July 24 states: "The Health Department has received an additional report of another prairie dog die-off in Old Concho."
The notice bluntly states that "Old Concho is now considered a plague-positive area."
The die-off occurred earlier in July.
Fleas, and the rodents they commonly live on and feed off of, act as hosts for the life cycle of the bubonic plague bacteria, Yersinia pestis.
Prairie dogs are quite susceptible to the disease and die quickly.
Since their hosts are dead and the fleas can no longer get a meal of blood from them, the insects abandon their hosts who die deep in their burrows.
They climb up and hang out near the entrance of the burrow, hoping to catch a ride and a meal on another passing animal, usually another rodent.
The new area of infestation is on the opposite side of Highway 61 northwest from the original infestation.
A map of the affected area has been posted on the Apache County website.
"They both happened during the same time period.
If it was the same mode of transmission, I don't know," said Apache County Public Health Director Chris Sexton.
Sexton said he could not be sure if rodents or some other type of animal is moving the fleas around Concho.
The most recent die-off occurred on vacant land in an area with a smaller number of prairie dog burrows.
Sexton said it was about 300 feet to the nearest residence.
He did not say who reported the die-off.
The area where the previous prairie dog die-off occurred, at the Jim and Marilyn Mineer property, was recently treated for fleas.
A crew from Coconino County Public Health dusted the affected burrows with an insecticide to kill any fleas that were still alive.
Mineer said in a telephone message that she was satisfied with the work done by the crew, calling it "very thorough."
On July 13, Dr. Joe Busch, a staff scientist with the Pathogen and Microbiome Institute at Northern Arizona University, took samples of fleas from burrows where the die-off occurred at the Mineer property.
Ten percent of the fleas sampled tested positive for the bubonic plague bacteria.
Sexton said that the burrows in the area of the most recent die-off will not be dusted because the property owners cannot be reached.
He said the dusting crew must have the owner's permission before entering their property.
Apache County does not conduct insecticide dusting of prairie dog burrows - they contract with Coconino County for that work.
Sexton said Coconino County staffers were unable to reach the property owners.
No one from Apache County has attempted to contact them, he said.
Sexton was not concerned about the bacteria spreading from the untreated burrows, noting that no die-offs had been reported in Concho Valley.
"If this was something highly transmissible, like measles or flu, we would take more precautions," he said.