BOB@BBT
01-09-2005, 10:20 AM
http://www.freep.com/sports/outdoors/eric8e_20050108.htm
ERIC SHARP: Contracting bovine TB is rare for humans
January 8, 2005
BY ERIC SHARP
FREE PRESS COLUMNIST
The story about the hunter who contracted bovine tuberculosis from a deer produced a rash of e-mails and calls from hunters concerned that the same thing could happen to them.
I decided to get the opinion of people on the front lines of the efforts to eradicate this disease -- state Department of Natural Resources veterinarians and deer researchers. They frequently run the risk of cutting up tubercular deer.
The hunter in Alcona County contracted the disease after cutting himself while gutting a deer.
"This was kind of a freak accident, but it was probably bound to happen," said Steve Schmitt, head of the DNR veterinary section. "A lot of us have cut ourselves while working on deer that we know have tuberculosis, but no one has been infected because we take some sensible precautions."
The DNR has done necropsies -- an autopsy of an animal -- on more than 300 deer infected with bovine TB, and field biologists have cut off the heads of hundreds of infected deer to send them to Schmitt's laboratory for testing. Schmitt said people working on the animals wear latex gloves and respirators, and some also wear an armored glove on the hand that is not wielding the knife.
"If we cut ourselves, we wash the wound out well and soak our hands in a disinfectant solution for a few minutes," Schmitt said. "Warm, sudsy water will do the job. Bovine tuberculosis isn't an easy disease to contract. I think you have to get a pretty good dose of the bacteria to become infected.
"You would probably have to cut into a lesion where bacteria are concentrated to get that kind of exposure. This is a good example of why hunters should wear latex gloves when gutting and wash their hands carefully after."
The state Department of Community Health said the infected hunter, whose name was not released, killed the deer in October but didn't seek treatment for some time. He finally went to a doctor because the wound didn't heal. He never became infectious to other people and has begun drug therapy, which could last more than a year but should result in a cure.
The hunter saw tubercular lesions -- sores -- on the inside of the deer's chest cavity when he gutted it, and he mentioned this to the doctor who treated his hand. The doctor tested for tuberculosis, and the test was positive for the same strain of bovine TB discovered in Michigan deer 10 years ago, the first outbreak of the disease known in wild whitetails.
"Even if you cut into one of those lesions, there doesn't appear to be much chance of you getting the disease if you don't cut yourself," Schmitt said. "There doesn't appear to be any aerosol factor" that would spray bacteria into the air.
When DNR researchers began working on tubercular deer, they were concerned about airborne spread of the disease and tested for it. The veterinarians and technicians wore small pumps with a hose that collected air from around their mouths and noses and pulled it through a filter.
"We never picked up any bacteria," Schmitt said. "Next, we put the end of the hose inside a deer carcass that was full of tubercular lesions, closed up the body cavity and ran the pump for eight hours. Still nothing.
"Finally, we cut open some lesions inside one of those deer, so we knew we had bacteria moving around in there, and ran it for another eight hours. We never found a single TB organism. This tells us that once the animal is dead, it's very hard for those bacteria to aerosolize."
Schmitt said the disease is found primarily in the lungs and lymph nodes and sometimes in the diaphragm, liver and the tissue lining the chest wall, "but we've never detected it in the muscle tissue. Apparently, it can't live there. That's why we don't think there's a chance of people contracting the disease by eating meat from infected deer.
"Even if you accidentally cut a lesion and contaminated the muscle tissue, you would still be safe if you cook it properly. Our recommendation is that people who take deer from known infected areas cook the venison a little longer, until the juices run clear."
Animal testing and pasteurization of dairy products have virtually eliminated the threat of bovine TB to humans in the United States. But before World War II it was common for people to contract it from infected milk and for farmers and slaughterhouse workers to be infected by diseased cattle.
Schmitt said the only other incident he knows where a human got bovine TB from a wild animal was in New Zealand. A researcher there cut herself while doing a necropsy on an infected possum.
"One thing I'm concerned about is that this might discourage hunters and have an adverse effect on our efforts to control the deer herd in that area," Schmitt said. "But we have to look at it in terms of relative risk. No one has got the disease from eating a deer, and one hunter got it by cutting himself.
"But in the last 10 years, how many hunters have been killed or hurt in car crashes on their way to or from that hunting area? I'll bet it's a lot more than one."
Contact ERIC SHARP at 313-222-2511 or esharp@freepress.com.
ERIC SHARP: Contracting bovine TB is rare for humans
January 8, 2005
BY ERIC SHARP
FREE PRESS COLUMNIST
The story about the hunter who contracted bovine tuberculosis from a deer produced a rash of e-mails and calls from hunters concerned that the same thing could happen to them.
I decided to get the opinion of people on the front lines of the efforts to eradicate this disease -- state Department of Natural Resources veterinarians and deer researchers. They frequently run the risk of cutting up tubercular deer.
The hunter in Alcona County contracted the disease after cutting himself while gutting a deer.
"This was kind of a freak accident, but it was probably bound to happen," said Steve Schmitt, head of the DNR veterinary section. "A lot of us have cut ourselves while working on deer that we know have tuberculosis, but no one has been infected because we take some sensible precautions."
The DNR has done necropsies -- an autopsy of an animal -- on more than 300 deer infected with bovine TB, and field biologists have cut off the heads of hundreds of infected deer to send them to Schmitt's laboratory for testing. Schmitt said people working on the animals wear latex gloves and respirators, and some also wear an armored glove on the hand that is not wielding the knife.
"If we cut ourselves, we wash the wound out well and soak our hands in a disinfectant solution for a few minutes," Schmitt said. "Warm, sudsy water will do the job. Bovine tuberculosis isn't an easy disease to contract. I think you have to get a pretty good dose of the bacteria to become infected.
"You would probably have to cut into a lesion where bacteria are concentrated to get that kind of exposure. This is a good example of why hunters should wear latex gloves when gutting and wash their hands carefully after."
The state Department of Community Health said the infected hunter, whose name was not released, killed the deer in October but didn't seek treatment for some time. He finally went to a doctor because the wound didn't heal. He never became infectious to other people and has begun drug therapy, which could last more than a year but should result in a cure.
The hunter saw tubercular lesions -- sores -- on the inside of the deer's chest cavity when he gutted it, and he mentioned this to the doctor who treated his hand. The doctor tested for tuberculosis, and the test was positive for the same strain of bovine TB discovered in Michigan deer 10 years ago, the first outbreak of the disease known in wild whitetails.
"Even if you cut into one of those lesions, there doesn't appear to be much chance of you getting the disease if you don't cut yourself," Schmitt said. "There doesn't appear to be any aerosol factor" that would spray bacteria into the air.
When DNR researchers began working on tubercular deer, they were concerned about airborne spread of the disease and tested for it. The veterinarians and technicians wore small pumps with a hose that collected air from around their mouths and noses and pulled it through a filter.
"We never picked up any bacteria," Schmitt said. "Next, we put the end of the hose inside a deer carcass that was full of tubercular lesions, closed up the body cavity and ran the pump for eight hours. Still nothing.
"Finally, we cut open some lesions inside one of those deer, so we knew we had bacteria moving around in there, and ran it for another eight hours. We never found a single TB organism. This tells us that once the animal is dead, it's very hard for those bacteria to aerosolize."
Schmitt said the disease is found primarily in the lungs and lymph nodes and sometimes in the diaphragm, liver and the tissue lining the chest wall, "but we've never detected it in the muscle tissue. Apparently, it can't live there. That's why we don't think there's a chance of people contracting the disease by eating meat from infected deer.
"Even if you accidentally cut a lesion and contaminated the muscle tissue, you would still be safe if you cook it properly. Our recommendation is that people who take deer from known infected areas cook the venison a little longer, until the juices run clear."
Animal testing and pasteurization of dairy products have virtually eliminated the threat of bovine TB to humans in the United States. But before World War II it was common for people to contract it from infected milk and for farmers and slaughterhouse workers to be infected by diseased cattle.
Schmitt said the only other incident he knows where a human got bovine TB from a wild animal was in New Zealand. A researcher there cut herself while doing a necropsy on an infected possum.
"One thing I'm concerned about is that this might discourage hunters and have an adverse effect on our efforts to control the deer herd in that area," Schmitt said. "But we have to look at it in terms of relative risk. No one has got the disease from eating a deer, and one hunter got it by cutting himself.
"But in the last 10 years, how many hunters have been killed or hurt in car crashes on their way to or from that hunting area? I'll bet it's a lot more than one."
Contact ERIC SHARP at 313-222-2511 or esharp@freepress.com.