North Carolina Wildlife Resources Commission

Midge Research Could Help Track the Spread of Hemorrhagic Disease

Author: NCWRC blogger/Wednesday, August 30, 2017/Categories: Wildlife Management

Midge Research Could Help Track the Spread of Hemorrhagic Disease

My name is Katherine Abbott and I’m a rising junior at N.C. State where I study conservation biology. This past summer, I had the amazing opportunity to work as an intern with the N.C. Wildlife Resources Commission, where I assisted with a box turtle study and worked on a variety of assignments for the communications department. One of those assignments provided me the chance to shadow a district biologist for two afternoons in the field conducting research on biting midges.

Midges are small flying insects, similar to gnats. Much like mosquitos, the females must consume blood to reproduce. Found all over the world, they are known to be biting pests. Certain species are known to be vectors of disease. In the U.S., one of the most important infectious diseases found in white-tailed deer is transmitted by midges: Hemorrhagic Disease (HD).

HD affects both domesticated and wild ruminants (deer, sheep, cows, etc.), symptoms of which are fever, swelling of the head and tongue, respiratory distress, lameness, emaciation and death. Particularly acute strains are capable of killing its host within one to three days of infection, but many often recover after experience only mild symptoms. Hemorrhagic Disease outbreaks typically affect less than 25 percent of a population, but the intensity and location of these outbreaks is extremely varied. Since midges reproduce too fast to be controlled by pesticides, there is little to do in the way of disease prevention outside of active management and recreational hunting.

So, if there aren’t any viable ways to prevent the spread of HD, then why are we doing the research? Since 2006, there have been an increasing number of outbreaks across Europe which have led to the spread of more exotic forms of HD only found in the Mediterranean. These tropical strains are carried by specific species of midges. Scientists are able to track the outbreaks by trapping, identifying and recording the species of midges found in those areas. The Southeastern Cooperative for Wildlife Disease Study (SCWDS) and researchers at the University of Georgia-Athens (UGA) have already begun doing this type of research on midges across the southeast to determine the disease’s presence in the U.S.

Their results so far? In 2013, the midge species known for carrying exotic HD had been found in Georgia, Florida, Alabama and Mississippi–areas in which these species haven’t occupied before. To see just how far the species has traveled, research is moving farther north into the Carolinas and Tennessee.

Jason Allen is the district biologist for the northern piedmont region. He spends his mornings in his home office responding to all sorts of questions from his community. Occasionally he helps educate the public and fellow staff on the science behind wildlife. His afternoons are spent in the field, lending his time and expertise to private land owners, the public, researchers and whoever else he meets along the way. Allen began working with the Commission 15 years ago as a technician at the Caswell Wildlife Depot where he gained experience working with hunters and managing multiple game lands. He worked his way up to crew leader and eventually became the Interim Northern Piedmont Management Biologist. After gaining more than 10 years of experience, he was hired as the biologist for all of District 5 that includes Rockingham, Caswell, Person, Granville, Guilford, Alamance, Orange, Durham, Randolph, Chatham and Lee counties.

Researchers from UGA have looked to Allen for expertise in placing midge traps around the piedmont of North Carolina. During the two days I spent working with him, we surveyed game lands in Butner and Caswell counties and placed light traps overnight to catch midges. Although it may be several months before the midges we collected will be processed and used in their research, the experience left me feeling excited about their work. The more we are able to learn about the strains and species responsible for these exotic outbreaks, the better we can become at finding a viable way to prevent them.

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