Iowa is in the midst of its second-worst outbreak of the often fatal deer disease known as EHD.
Epizootic hemorrhagic disease, which killed almost 3,000 deer last year in more than 60 Iowa counties, has already killed about 550 this year, with the toll continuing to mount, said Tom Litchfield, the Department of Natural Resources’ deer biologist.
The disease is caused by a virus transmitted by the bite of an infected midge, a small insect that flourishes in hot, dry summers like the last two.
Last year the disease was most prevalent in south-central Iowa and the Loess Hills region of western Iowa. This year a band of counties in Eastern Iowa, including Linn, Johnson and Cedar, have been among the hardest hit, according to Litchfield.
As of Friday the death toll stood at 44 in Linn, 46 in Johnson and 50 in Cedar, he said.
The counties with the most EHD deaths, he said, are Davis (70), Lee (63) and Van Buren (54), all in southeast Iowa.
Iowa is usually on the northern fringe of the range of the disease, which kills relatively few deer in the state during a normal year. Until last year, the state’s worst EHD outbreak occurred in 1998, when 457 deer died of the disease.
Litchfield said the death tolls reflect deer reported to the DNR. The actual numbers could be much higher because most EHD-killed deer perish in remote areas where no one sees them, he said.
The virus causes the animal's cell walls to break down, resulting in the buildup of fluids, internal bleeding and a high fever. The deer usually dies within four days of the onset of the fever, which drives the deer to water, where their carcasses are often found.
The threat subsides when frost kills the midges.
Unlike chronic wasting disease, another fatal deer disease confirmed in Iowa, EHD cannot be transmitted from deer to deerWhile the meat of an EHD-infected deer is safe to eat, deer shot in the latter stages of the disease will likely have symptoms that affect the meat’s quality, he said.