Plague found in eastern Wyoming prairie dogs
• Avoid unnecessary exposure to rodents
• Avoid contact with rodent carcasses
• Avoid areas with unexplained rodent die-offs
• Use insect repellent on boots and pants when in areas that might have fleas
• Use flea control products for pets, and properly dispose of rodents pets may bring home
The plague, a serious bacterial infection that can be deadly to humans, was recently found in a prairie dog town in northeastern Wyoming, according to the Wyoming Department of Health. Three prairie dogs infected with plague were found recently in different parts of the Thunder Basin National Grassland, in Converse County, for the first time in more than 15 years, according to WDH.
Local U.S. Forest Service personnel have described seeing signs of significant prairie dog die-offs in the area.
Sometimes referred to as the “black plague,” the disease is caused by a bacterial strain called Yersinia pestis. This bacteria is found on animals throughout the world and is usually transmitted to humans through fleas or other insects, such as ticks and lice.
While not a cause for panic, the plague is nothing to mess with, and can also be transmitted from person to person, through the air, via “cough droplets,” according to WDH.
“Plague is a serious bacterial infection that can be deadly for people and for animals, including pets, if not treated promptly with antibiotics,” said Alexia Harrist, state epidemiologist and acting state health officer with WDH. “The disease can be transmitted to humans from ill animals and by fleas coming from infected animals.”
“While human plague infections are thankfully rare, we expect the risk for plague exists all around Wyoming,” Harrist said. Six human cases of plague have been confirmed with exposures in Wyoming since 1978; the last one was reported in 2008.
There are an average of seven human cases across the nation each year. It is not considered a seasonal disease, but it is predominantly found in the southwest between the months of May and October.
The risk of plague is highest in areas that have poor sanitation, overcrowding, and a large population of rodents. To date for 2017, no human cases have been identified in the Wyoming area, relating to the recent outbreak. Six cases have been confirmed in Wyoming since 1978, with the most recent known human infection in 2008, according to the department.
However, three people in New Mexico have contracted plague to date this year. New Mexico Department of Health says all three, required hospitalization but there have been no deaths related to the plague so far this year. And an outbreak in a prairie dog town in Texas, at the Muleshoe National Wildlife Refuge near Muleshoe, has park officials closing a portion of the refuge.
There are an average of seven human cases every year in the U.S., and 1,000 to 2,000 cases reported worldwide with the highest incidences in Africa.
CARRIERS OF THE DISEASE
Animals are also at risk for the plague, and have the potential to transmit the disease. Carriers of this disease include rats, squirrels and mice; the disease is typically transmitted when a rodent either bites, or is bitten by a dog, according to Pet MD, but can also be transmitted through fleas.
A cat in Colorado’s rural northwest Weld County tested positive for plague this year, in early June. The cat, along with its owner, was treated for the disease.
“The presence of plague reminds residents to keep fleas off pets and use appropriate flea control products” said Mark E. Wallace, MD, MPH, executive director of the Weld County Health Department. “It’s good practice to use an insect repellant if you will be working, playing or camping in areas where fleas may be present.”
In 2015, a plague-infected family dog spread the disease to four Colorado residents, according to the U.S. Centers for Disease Control and Prevention. According to reports, this was the first known dog to human infection of the plague.
The dog, a 2-year-old American pit bull terrier, was euthanized following a quick health decline, including fever and jaw rigidity, according to health officials, and was tested for the plague after its owner was admitted to the hospital.
“Pets that are allowed to roam and hunt can bring infected fleas from dead rodents back into the home, putting you and your children at risk,” Paul Ettestad, New Mexico public health veterinarian for the Department of Health, said in a press release. “Keeping your pets at home or on a leash and using an appropriate flea control product is important to protect you and your family.”
While more cases like this can be dug up, officials say there’s no cause for a bubble room yet, despite ancient history of medieval times, where the plague, or “black death,” was responsible for the deaths of millions of people in Europe.
But precaution is important, and knowledge can be key to successfully fighting a plague infection.
A person usually becomes ill with bubonic plague two to six days after being infected, according to WDH. When bubonic plague is left untreated, plague bacteria invade the bloodstream. The infected person may experience high fever, chills, coughing and breathing difficulty, and expel bloody sputum. If plague patients are not treated, the disease can progress quickly and result in death.
According to plague experts at the Center for Disease Control, a patient diagnosed with suspected plague should be hospitalized and medically isolated. Persons who have been in close contact with a plague patient, particularly a patient with plague pneumonia, should also be identified and evaluated. The U.S. Public Health Service requires that all cases of suspected plague be reported immediately to local and state health departments.
While most in the agriculture industry are in no hurry to save the prairie dog population, and would be just fine with them going down medieval style, a vaccine administered with peanut-butter flavored bait has been successfully tested on plague infested prairie dog towns, according to a U.S. Geological Survey study published in the journal EcoHealth.
In an effort to increase populations of endangered black-footed ferrets and conserve the prairie dogs they rely on for survival, a vaccine was developed by scientists at the USGS National Wildlife Health Center and the University of Wisconsin- Madison. According to the scientists, the vaccine elicits a protective immune response that can help the dogs fight off infection upon later exposure to the disease.
“Plague is devastating to prairie dogs, a keystone species of grassland ecosystems,” said Tonie Rocke, a USGS scientist and the project lead. “Our goal in developing an oral plague vaccine is to provide another tool for land managers to reduce the effects of plague outbreaks on prairie dog colonies. This reduction could have positive impacts on conservation of the threatened Utah prairie dog and survival of the endangered black-footed ferret, a prairie dog-dependent species.”
Both ferrets and prairie dogs are highly susceptible to the disease. The current method for controlling plague consists of dusting prairie dog colonies with insecticide to kill fleas that transmit the pathogen. Although dusting has been effective in controlling the spread of plague, it is labor-intensive, and some flea species may develop resistance to the pesticide, according to the scientists.
Plague symptoms in people can include fever, swollen and tender lymph glands, extreme exhaustion, headache, chills, coughing, difficulty breathing, abdominal pain, vomiting and diarrhea. People who are ill should seek professional medical help.
Plague symptoms in animals can include enlarged lymph glands; swelling in the neck, face or around the ears; fever; chills; lack of energy; coughing; vomiting; diarrhea and dehydration. Ill animals should be taken to a veterinarian.
More information about plague is available from WDH at https://health.wyo.gov/publichealth/infectious-disease-epidemiology-unit/disease/plague/ or from the federal Centers for Disease Control and Prevention at http://www.cdc.gov/plague/. ❖