From his office in Lena, Ill., 35 miles south of New Glarus, Wis., Doug Dufford of the Illinois Department of Natural Resources has watched chronic wasting disease (CWD) take its toll on wild deer herds in both states.

Wildlife officials on each side of the Illinois-Wisconsin border detected the always-fatal neurological disease in 2002, but a much more aggressive fight of the disease in Illinois has kept infection rates around 1 percent. In pockets of Wisconsin, where hunter resistance discouraged large-scale deer removals, one of every two mature bucks and one of every four adult females is now infected with the mad cow-like disease.

From afar, Dufford realizes Minnesota is trying to extinguish its second outbreak ever of CWD in the wild. At the same time, there’s an outbreak of CWD in captive deer, centered on a Crow Wing County farm that promotes private hunts. Unlike Minnesota, Illinois doesn’t allow shooting of penned deer.

Dufford said he wholly agrees with Minnesota unleashing heavy firepower to remove as many CWD-positive deer as possible in Fillmore County. Last week, federal sharpshooters settled into an area between Preston, Fountain and Lanesboro to compound the effort. The “hot zone’’ culling began with a two-week special hunt and four weeks of additional deer removals by area landowners before the sharpshooters arrived Monday from U.S. Department of Agriculture’s Wildlife Services division.

Testing brain and lymph tissues from thousands of whitetails harvested in the area has detected nine CWD-positive deer in a narrow cluster. The ninth was confirmed Friday.

“The best strategy is to hit it with everything you’ve got and hope for the best,’’ Dufford said. ‘’It’s an opportunity you only get once.’’

If CWD becomes established in Minnesota, as it has in 16 Illinois counties, disease fighting affects every annual hunting season, Dufford said. Illinois’ approach has been to conduct aerial surveys of deer densities in the infected zones and aggressively cull the most populated 5-by-5 mile areas.

Extra hunting is permitting in those hot zones, followed by mandatory organized sharpshooting campaigns for about 50 Illinois DNR wildlife biologists, foresters, non-game personnel and fisheries staff.

“In the early days it was voluntary — anyone who was willing,’’ Dufford said. “Then we made it mandatory.’’

He said the agency took guidance from USDA’s wildlife services team, the original sharpshooters.

“We watched how they did it and used them as an example to train our own staff,’’ Dufford said.

Now, when extra hunting is followed by Illinois DNR sharpshooting, deer numbers in a designated block drop noticeably, affecting hunts in subsequent years, Dufford said.

“You’re not achieving disease control if you don’t lower deer densities,’’ he said.

USDA Wildlife Services District Supervisor John Hart of Grand Rapids, Minn., said a crew of four to seven staff biologists and technicians will patrol for deer in the Minnesota hot zone, possibly until March 19.

The highly trained federal sharpshooters, more commonly used to fix beaver damage, control problem wolves and remove wildlife from airports, are working around the clock to shoot as many deer in and around the small home range of four female deer that have tested positive for CWD. Hart said some team members spread corn for bait during the day and seek landowner permission to hunt where deer are congregating.

“Certainly not all landowners are inviting us onto their land, but cooperation has been good,’’ he said.

Most shooting is done at night with .308 rifles outfitted with night vision scopes and sound suppressors. Scouting is aided by thermal imaging equipment that can detect deer on the move or in beds from distances of up to a half-mile. Shots are made from ground blinds, tree stands and vehicles and the scopes are good for distances of 100-200 yards.

The goal is to remove five to 10 deer per shift. Eighteen deer were harvested in the team’s first three full days of work. The carcasses are refrigerated and released for human consumption if tissue samples test negative for CWD.

The Wildlife Services contract is not to exceed $290,000, and the tally could be lower. But all included, the CWD fight in southeastern Minnesota that started last fall likely will cost taxpayers $650,000 to $700,000, the DNR said.

USDA sharpshooters also were used by the DNR in 2011 to stop an outbreak of CWD in wild deer around Pine Island.

In that case, the team removed more than 600 deer of all types over a broad area. The Fillmore County effort is focused only on adult deer in a small area where the outbreak appears to be contained.

“Here we are zeroing in on a bull’s-eye,’’ Hart said.