Lice On Okanogan Fawn ‘Anticipated’ To Be Same As Kind That’s Affected Muleys To The South

Follow-up on last week’s report that louse problems affecting mule deer herds further south on the eastern slopes of Washington’s Cascades may have arrived in the ungulate’s stronghold, Okanogan County.

The latest weekly wildlife report from the Department of Fish & Wildlife says:

Deer Management: After consultation with agency veterinary staff, Assistant District Biologist Heinlen and local Enforcement Sergeant Brown collected the fawn showing advanced hair-slip symptoms seen earlier during spring surveys. They found the animal heavily infested with lice. Biologist Heinlen shipped a lice sample to the US Department of Agriculture Animal and Plant Health Inspection Service Veterinary Services laboratory in Ames, IA for species identification. It is anticipated to be Bovicola tibialis, the exotic fallow deer lice implicated in widespread hair-slip syndrome seen in other parts of the state.

The fawn was found near Loomis in the lower Sinlahekin Valley, according to Sgt. Jim Brown.

A photo accompanying the note shows its underside and several brown specks which are identified as lice.


It’s the second mule deer in the county with apparent hairslip, according to last week’s wildlife roundup.

In Chelan County, just to the south, WDFW reports:

Biologist Gallie continued with spring deer composition counts in Chelan County this week. The goal being to look at adult and fawn ratios and presumed winter kill severity. Due to this winter’s conditions, we do not expect an unusually high winter kill. With 10 of the 13 routes completed, ratios are falling within normal survival ranges at 46 fawns per 100 adults. Spring counts also allow for the identification of apparent hairloss syndrome that is present in the Chelan County herd and its geographic distribution. Thus far, hairloss has been documented in on each route (this has not increased known distribution), with approximately 6% of the observed deer show obvious symptoms. It increased over observed rates during the past several years, and is lower than the highest occurrence rate.

But before we all run out and panic — I’m an Okanogan County deer hunter and yes, my hair is already on fire as I write this — take a second to read through the prepress version of an article that ran in the August 2010 issue of Northwest Sportsman magazine on the subject and why it may not be the end of the world.

HEADLINE As Lice Spread Into Muley-rich Chelan Co., Biologists Have More Questions

SUBHEAD Maybe it’s not just bugs leading to deer deaths, but a combination of things.

YAKIMA—At first it seemed like a horrible but straight forward new wildlife dilemma. A strain of exotic lice, brought to Washington on the backs of imported fallow deer, had infested Kittitas and Yakima County mule deer, were spreading out fast, and because their new hosts didn’t have centuries of built-up tolerance, were creating a major die-off.

Infected muleys would be so irritated by the little biters they’d scratch away huge patches of hair, leaving them much more vulnerable to winter’s cold.

By 2005 Jeff Bernatowicz and his fellow wildlife biologists realized they had a major problem, first when their deer spring surveys came up short, then when fall harvest reports came in way below recent trends. Then that spring several landowners reported finding numerous carcasses in their back pastures, all with significant hair loss.

The louse was identified and the verdict seemed to be in. Although exotic animal game farms were now illegal in this state, the damage was already done.

Neither the lice nor the virus appear to pose any direct threat to hunters. However, when field dressing or butchering any wild game, the use of latex gloves and carefully washing up with a good disinfectant soap afterwards is advised.


WHAT MOST BIOS expected was a steady gradual spreading of this nasty pest into other counties and eventually bordering states. The hope was that immunity, or at least greater tolerance would develop, but no one knew how long that might take.

(Fortunately for the state’s second largest herd, the parasite didn’t appear to attach itself to elk.)

Part of that gradual spread theory is now playing out. The louse has moved at least as far north as several Grant County islands in the Columbia River, and since 2008 there have been at least 18 cases of exotic lice in Chelan County.

“We’ve had confirmed cases all the way from the Chelan-Kittitas County border all the way to north of the Entiat River,” notes Dave Volsen, big game biologist in Wenatchee. “But the only dead mule deer with the parasite on it was a roadkill in the Swakane in ’09.

“If Kittitas County is symbolic, we’re going to take a hit, but at this point we just don’t know. The deer may be developing a tolerance. Some have the lice and don’t show any real hair loss. All we can do is continue to monitor the situation and hope for the best.”

HOWEVER, AFTER FIVE YEARS of monitoring in his own district and seeing what’s been happening in other parts of the country, Bernatowicz now says he has to really question some of those early assumptions.

“We expected a gradual spread, but in 2008, mule deer all the way back in South Dakota were suddenly infected and dieing. Then in ’09 they had outbreaks in Nebraska, Wyoming, Idaho and California. I talked to the biologists in those states, got their reports, and it was the same exotic.”

These alien lice die quickly once their host expires, thus can only be spread by direct contact – an infected live deer rubbing up against a healthy one – so obviously it wasn’t hunter-borne carcasses that brought them to such distant states.

“No, and our infected mule deer didn’t suddenly migrate all the way back to South Dakota, skipping all the state herds in between,” Bernatowicz adds. “So now I think it’s highly possible that the lice have been here the whole time, and it’s something else, something in combination with them, that’s causing this problem.”

Back in the 1700s, the state’s namesake, George Washington, was the first to bring fallow deer to the country, turning them loose on his Mount Vernon estate. Over time these little deer were imported to almost every state, so, yes, this parasite could be well established in local deer herds. But then why is it only now killing so many of its hosts?

“One possibility is that a virus is out there that’s affecting the deer’s immune system,” Bernatowicz ventures, “making it more vulnerable to the lice. A strain of adenovirus has been detected in California mule deer, one that originated with domestic livestock, and we feel that may be hitting up here, particularly along the Columbia River.

“Our Yakima Training Center mule deer numbers are now very bad, with all the herds have been down by 50 percent or more. Then when we did goose nest surveys along the Columbia, on one small island we found about a dozen dead deer, no live ones. Unfortunately, the bodies were too decomposed to take tissue samples for a culture, but there was no significant hair loss, and with that many dead in that close proximity, a virus seems likely.”

Plus, a virus might explain why wildlife agents are finding that some muleys can play host to these lice without rubbing huge hair patches while others groom themselves into real trouble.

“But there’s just so much about this that we still don’t understand,” Bernatowicz admits. “For example, even here in Kittitas County, where we’ve seen it since 2005, it has such a checkerboard pattern. In one area the deer are almost totally wiped out. Then 20 miles away they’re doing just fine. It’s almost like a bunch of spot fires, really patchy. Unfortunately, we have no means of combating it. All we can do is let it run its course.” –Leroy Ledeboer

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One thought on “Lice On Okanogan Fawn ‘Anticipated’ To Be Same As Kind That’s Affected Muleys To The South”

  1. If there’s a combined hopeful and frightening note in all this it comes out of what we saw in Kittitas and Yakima Counties. When I first reported on this exotic louse infestation, its effects appeared to be totally devastating, with landowners finding dozens of dead deer, all with significant hair-loss. The consensus was it was deadly, uncontrollable and would spread across the N.W. and beyond in no time. Well, that deadly part at least hasn’t always played out up to this point – ala Kittitas County – outbreaks are spotty – and the spread has at least been slower than we once imagined. Unfortunately one bad part is that spread is taking place, and as Bernie said “All we can do is let it run its course.”
    And of course hope, hope that our deer develop resistance before another major die-off hits.

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