DES MOINES, Iowa — Warren County, Iowa, is the epicenter of a disease that has killed at least 1,800 whitetail deer in Iowa this year.

Brought on by a virus, the epizootic hemorrhagic disease causes heart and lung tissue in infected deer to weaken and burst. In Warren County, it has killed at least 773 deer — and likely many more, officials say.

"We know the number is going to be several times larger than what we have reported," Warren County conservation officer Craig Cutts told the Des Moines Register. "We have probably lost thousands of deer. In fact, we know we have."

© Bryon Houlgrave/The Register Deer stand out against freshly fallen snow at Walnut Woods park in West Des Moines after a winter storm dumped snow across parts of central Iowa on Sunday, April 15, 2018.

EHD is not a threat to humans — the virus cannot be transmitted by eating infected deer meat — but it threatens to thin herds and affect hunting in central Iowa.

"I'm definitely concerned," said Jim Priebe, director of the Warren County Conservation Board.

An avid hunter, Priebe usually buys three or four doe tags each year. This year, he's only buying one.

"I hunt in southern Warren County a little later in the year, and I’m afraid I'm not going to be able to put venison in my freezer this year," he said.

Deer tag sales are down across the state, Iowa Department of Natural Resources officer Richard Smith said. The DNR has sold 130,487 so far, compared to 143,966 at the same time last year.

Doe tag sales are down, too. Each year, the DNR releases a set number of doe tags in each county to help control the state's deer population. There are about 600 doe tags still remaining from the 2,700 that were available in Warren County.

Last year, the county's doe tags were sold out by October.

Deer hunting in Iowa provided an economic impact of nearly $214 million in 2014, the most recent year for which data is available, the DNR said. That counts hunting equipment, food, lodging and gas, among other expenditures.

A © Press-Citizen file photo Epizootic hemorrhagic disease causes has killed at least 773 deer in Warren County, Iowa, officials say. ltogether, the sport supports more than 2,800 jobs and provides more than $67 million in earnings, the state estimates.

Cutts said hunters are reporting fewer deer in Warren County, and he's seeing fewer animals in the fields.

"I know that because I'm checking them, and I can also say that because I’ve been hunting myself on my own farm," he said.

EHD is not new to Iowa. The disease claims some deer every year, but large-scale population losses at the county level or larger are rare. The last large-scale losses were reported in 2012 and 2013 in eastern and southern Iowa.

The virus is spread by infected biting midges, which are tiny flies, and is more prevalent in dry years because it spreads when deer congregate at fewer watering holes, officials say.

Midges breed in the mudflats around watering holes.

Infected deer are attracted to water to combat the high fever and dehydration caused by hemorrhaging. Deer die usually within a few days of infection.

EHD is not related in any way to chronic wasting disease, a neurological disease that causes a deer's nervous system to attack its brain. Unlike EHD, chronic wasting disease can be spread from deer to deer and cause widespread population loss.

Chronic wasting disease: What is the 'Zombie' deer disease, and could it affect humans?

The large number of EHD deaths this year is probably the result of the state's increasing deer population, Cutts said. According to the DNR, the state's deer numbers have been increasing since 2014.

Since the disease does not significantly affect deer every year, herds do not build up a resistance, Priebe said.

"The deer herd can recover from this, but if we had another year where we had the same conditions, we might end up with a very low population for a number of years," he said. "If everything else stays stable, that deer population will pop back within two to three years."

This article originally appeared on Des Moines Register: Disease has killed hundreds, potentially thousands of deer in central Iowa