{"id":43938,"date":"2021-11-04T11:00:00","date_gmt":"2021-11-04T11:00:00","guid":{"rendered":"https:\/\/dh.durangoherald.com\/tj\/in-colorado-wildlife-disease-is-the-next-frontier-of-climate-change\/"},"modified":"2026-03-31T09:16:29","modified_gmt":"2026-03-31T09:16:29","slug":"in-colorado-wildlife-disease-is-the-next-frontier-of-climate-change","status":"publish","type":"post","link":"https:\/\/dh.durangoherald.com\/tj\/in-colorado-wildlife-disease-is-the-next-frontier-of-climate-change\/","title":{"rendered":"In Colorado, wildlife disease is the next frontier of climate change"},"content":{"rendered":"\n

\"Mule
Mule deer and other foragers are more susceptible to disease when their food is limited and less nutritious, one of the many effects of climate change, Colorado Parks and Wildlife biologist Brad Weinmeister said. (Jerry McBride\/Durango Herald)<\/span>Jerry McBride<\/span><\/figcaption><\/figure>\n<\/p>

Colorado Parks and Wildlife announced last week that at least two mule deer had died of bluetongue disease in Alamosa.<\/p>\n

Bluetongue virus, a hemorrhagic disease that can devastate white-tailed deer populations and also infect mule deer, elk, bighorn sheep, pronghorn and bison, has been particularly severe in the western United States this year.<\/p>\n

The disease leaves deer lethargic, disoriented and unresponsive. They can foam at the mouth, bleed from the nose, and their tongues can swell and turn blue. Death comes quickly, often within one or two days, CPW\u2019s news release said.<\/p>\n

\"Deer
Deer with hemorrhagic disease typically die within a a few days. They often foam at the mouth or bleed from the nose, and their tongues can swell and turn blue. (Courtesy of Colorado Parks and Wildlife)<\/span>Courtesy of Colorado Parks and Wildlife<\/span><\/figcaption><\/figure>\n<\/p>

It\u2019s one of two hemorrhagic diseases, epizootic hemorrhagic disease being the other, typically found in Colorado between the months of August and October.<\/p>\n

\u201cPretty much every year we get some EHD and bluetongue activity,\u201d said Karen Fox, a wildlife pathologist with CPW. \u201cThis year\u2019s been really bad.\u201d<\/p>\n

\u201cIt\u2019s probably the worst one that I\u2019ve seen, and I\u2019ve been around about 10 years,\u201d Fox said.<\/p>\n

Fox estimates that statewide wildlife deaths are triple or quadruple a normal year.<\/p>\n

\"At
At least two mule deer in Alamosa died after being infected with bluetongue virus. Scientists say climate change will worsen bluetongue and other hemorrhagic diseases. (Jerry McBride\/Durango Herald)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

With no catastrophic die-offs like those seen in eastern Washington, where there have been more than 500 reports of dead deer this year, Coloradans have yet to notice.<\/p>\n

But wildlife managers are warning that Colorado could see the explosion of these diseases with climate change.<\/p>\n

It comes down to how hemorrhagic diseases are transmitted.<\/p>\n

Flies or midges bite the deer, infecting them. Flies and midges that carry bluetongue and EHD typically appear around standing water.<\/p>\n

\u201cThere\u2019s definitely an association between water and the disease,\u201d Fox said. \u201cAnd that\u2019s because the little gnats they develop \u2026 in mud.\u201d<\/p>\n

Lakes and ponds can be sources of disease, Fox said, but even a pool of water in the divot of a hoof print can spread bluetongue and EHD.<\/p>\n

The close link between hemorrhagic diseases and water make it more common in the southeastern U.S., Fox said. Yet, counterintuitively, it\u2019s actually drought that worsens outbreaks.<\/p>\n

\u201cIf you look at the literature, there\u2019s more of an association with drought in this disease than with lots of moisture,\u201d Fox said. \u201cThat\u2019s because you have the water and then it recedes and it allows you to get more of this muddy habitat for the gnats to proliferate in.\u201d<\/p>\n

\u201cWhat drought does is it forces animals to congregate,\u201d said Erik Hofmeister, a research virologist with the U.S. Geological Survey.<\/p>\n

Drought also brings wildlife together, leading to more infected animals, Hofmeister said.<\/p>\n

The Southwest\u2019s most severe drought on record made much of Colorado a perfect environment for the spread of both bluetongue and EHD this fall, a prelude of what scientists say will come.<\/p>\n

\"Elk
Elk are among the many species that can be infected by hemorrhagic viruses, though these diseases are often most devastating for white-tailed deer. (Jerry McBride\/Durango Herald)<\/span>Jerry McBride<\/span><\/figcaption><\/figure>\n<\/p>

From January 2020 to August 2021, the Southwest U.S. experienced its lowest precipitation total since 1895, according to a report issued by the National Oceanic and Atmospheric Administration on the 2020-21 Southwestern U.S. Drought Monitor. The region also had its third-highest daily average temperatures since 1895.<\/p>\n

The report said the warm temperatures that drive drought would only continue to increase as climate change worsens.<\/p>\n

But climate change will exacerbate hemorrhagic disease in other ways, too.<\/p>\n

According to CPW\u2019s news release, cases of bluetongue and EHD fade when midges die off with the fall\u2019s first frost. But climate change models show the frost-free season will increase across the West. In the Southwest, the lengthening of the frost-free season is projected to increase twice as much as the rest of the country, according to the Third National Climate Assessment released in 2014.<\/p>\n

It\u2019s possible that with a longer frost-free season the midges and flies that transmit bluetongue and EHD could survive longer, spreading more disease.<\/p>\n

Climate change is also altering the food that deer and other wildlife rely on, making them more susceptible to disease.<\/p>\n

\u201cSome of these dry years we aren\u2019t getting the quantity or quality of vegetation that we used to in the past,\u201d said Brad Weinmeister, a wildlife biologist with CPW. \u201cYou tie that back into disease and the animals don\u2019t have as good of food to eat. It\u2019s not as available, it\u2019s not as nutritious. So they\u2019re more stressed, which is going to put them at higher risk of disease.\u201d<\/p>\n

With the risk that climate change poses, wildlife managers have taken notice.<\/p>\n

\u201cPeople have specifically talked about these diseases being affected by climate change,\u201d Fox said.<\/p>\n

However, the challenge is not trying to stop bluetongue or EHD. The challenge is simply to understand the scope of the problem.<\/p>\n

\"Passive
Passive surveillance prevents wildlife managers from understanding the scope and timing of problematic diseases. (Jerry McBride\/Durango Herald)<\/span>cca<\/span><\/figcaption><\/figure>\n<\/p>

CPW and many other federal and state wildlife management agencies use passive disease surveillance. If a person sees a dead or disoriented deer, they reach out to Fox and CPW who then investigate and test the animal to get a diagnosis.<\/p>\n

CPW does not go out and actively conduct studies to understand the prevalence of hemorrhagic disease or the effect that they have on deer populations.<\/p>\n

\u201cWe\u2019re not getting enough samples to make those inferences,\u201d Fox said. \u201cIt\u2019s just kind of anecdotal. It\u2019s more subjective.\u201d<\/p>\n

With passive surveillance, scientists lose much of the key information they need to manage outbreaks, Hofmeister said. They know neither the timing nor the location of the disease.<\/p>\n

\u201cWith passive disease surveillance, you really don\u2019t know the breadth of what\u2019s out there,\u201d Hofmeister said.<\/p>\n

Wildlife managers are left blind to make key decisions about wildlife populations affected by disease. And unlike humans, disease in wildlife is much harder to manage.<\/p>\n

\u201cThere\u2019s steps that can be taken, but it\u2019s not like going to the local pharmacy and getting a flu shot to decrease the number of cases,\u201d Weinmeister said. \u201c\u2026 You can\u2019t do that with animals.\u201d<\/p>\n

Bluetongue and EHD are just two of the diseases that affect deer and other wildlife in Southwest Colorado. With worsening climate change and passive surveillance, wildlife managers face perhaps their toughest task.<\/p>\n

Fox said she and others who study wildlife disease are already beginning to see the changes.<\/p>\n

\u201cWe\u2019re moving from a phase of prediction to a phase of documentation,\u201d Fox said.<\/p>\n

\u201cI think that we\u2019ll start seeing a lot more coming out in the next decade here, where people are looking at those predictions and saying, \u2018Yeah, we can detect that something has truly changed.\u2019\u201d Fox said. \u201cAnd I think this is maybe one of the first things where we\u2019ve had enough data over the years to be looking at it and say, \u2018Yeah, it\u2019s changing.\u2019\u201d<\/p>\n

ahannon@durangoherald.com<\/a><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

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