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Brainworm
Michigan
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Anony Mouse 17-Mar-17
From: Anony Mouse
17-Mar-17
Just a FYI from ProMed:

BRAINWORM - USA: (MICHIGAN) ELK ******************************* A ProMED-mail post ProMED-mail is a program of the International Society for Infectious Diseases

Date: Wed, 15 Mar 2016, 2:40 PM Source: Mlive.com [edited]

A Michigan DNR officer killed an elk suspected of having a rare case of brainworm after it blocked a popular snowmobile trail in Northern Michigan.

The animal's head is being sent for testing by pathologists in Lansing, authorities said. The 500-pound bull elk was shot in late February [2017] in Otsego County. Sgt. Mark DePew said he arrived at the scene after snowmobilers called 911. "The elk had that snowmobile trail on lockdown. There were snowmobiles on either side of him, and he just got in the middle of the trail and wouldn't let anybody go by," DePew said. "Every time someone would try to approach him, he would get a little aggressive." By the way the elk was acting; DePew said he suspected the animal had brainworm. He had to put it down at the scene.

Brainworm has been confirmed in a handful of times in Michigan elk in the last 5 years. The parasite creates problems with the large animal's nervous system, causing a noticeable change in behavior. Brainworm is found in much of eastern North America, places that have a large white-tailed deer population.

These 2-inch worms, as thin as a human hair, are such a common parasite for deer that it's estimated half of Michigan's deer herd has them, said Thomas Cooley, a wildlife biologist and pathologist for the DNR's Wildlife Disease Lab in Lansing.

When a deer picks up brainworm, the parasite typically does not penetrate the brain tissue or cause problems for the animal. But in an abnormal host - like a moose or an elk - it can get inside the brain tissue. It damages the nervous system, causing behavior changes and can result in death. "It's a relatively rare occurrence, even now," Cooley said. State records show there have been 6 cases of brainworm confirmed between 2012 and 2016.

An elk with brainworm likely would appear thin, lethargic, and oblivious to its surroundings. "They might be standing in a road, or a pasture, or a barnyard. They may come in with cattle or horses. They don't act right," Cooley said. DePew said he's heard of infected elk befriending strange things, like a cow or even someone's vehicle.

Suspected brainworm cases that need to be confirmed are brought to the lab in Lansing. In this elk's case, pathologists will remove its skull cap and examine the brain, trying to find the actual worm. "You can easily miss it," Cooley said of the small parasites. Half the brain will be sent for microscopic study.

Many of the Michigan's suspected brainworm cases have come from Otsego County and the surrounding area. This makes sense, as it's the heart of Michigan's elk country. In 2014, conservation officers estimated Michigan had 680 elk.

DePew said he's handled more than half a dozen suspected brainworm cases in his 8 years working out of the DNR's District 3 Gaylord office. He has some advice for people who want to befriend one of these massive animals, especially if the animal is allowing a person to get close to them: Don't do it. "A wild animal that does not have the fear (of humans), that should be the 1st caution to the public," DePew said. "With a big 500-pound animal, they can be unpredictable."

[Byline: Tanda Gmiter]

-- Communicated by: ProMED-mail from HealthMap Alerts

[The brainworm (or meningeal worm), _Paralephostrongylus tenuis_, is a common parasite of white-tailed deer (_Odocoileus virginianus_) in eastern North America. In its natural host (the white-tailed deer) it is usually non-pathogenic, but it causes neurologic disease when it infects elk (_Cervus elaphus_), moose (_Alces alces_) and caribou (_Rangifer tarandus_). It has also been reported to infect sheep and goats.

The life cycle of _P. tenuis_ is complex and multi-staged. Adults will lay eggs on the dura mater (the outer layer of the meninges) of the brain or directly into the blood stream of an infected host. The eggs hatch into 1st stage larvae, which travel in the bloodstream to the lungs where they travel up the respiratory tract, are swallowed, and then pass out of the body in the mucus coating of fecal pellets. Gastropods fed on this mucus and ingest the larvae, where they develop into a 2nd and 3rd stage. Infected gastropods may then be accidentally ingested by an herbivore, and the larvae moves from the gastrointestinal tract to the bloodstream, reaching the central nervous system, where they develop to adults and the cycle begins over again. - Mod.PMB

A HealthMap/ProMED-mail map can be accessed at: .]

[See Also: 2004 ---- Moose die-off - USA (AK) (02) http://promedmail.org/post/20040407.0945 Moose die-off - USA (AK) http://promedmail.org/post/20040404.0931 2001 ---- Moose die-off - Canada (Nova Scotia) (04) http://promedmail.org/post/20010927.2366 Moose die-off - Canada (Nova Scotia) (03) http://promedmail.org/post/20010925.2338 Moose die-off - Canada (Nova Scotia) (02) http://promedmail.org/post/20010924.2320 Moose die-off - Canada (Nova Scotia): RFI http://promedmail.org/post/20010918.2253] .................................................sb/pmb/ao/dk

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