Bovine Tuberculosis

What is Mycobacterium bovis (M. bovis)?

• In the U.S., most people with tuberculosis (TB) are infected with Mycobacterium tuberculosis.
• M. bovis is another mycobacterium that can cause TB in people.
• M. bovis is most commonly found in cattle and other animals such as deer, elk and bison.
• It can infect the lungs, lymph nodes and other parts of the body.

How common is human disease from M. bovis?

• Fewer than 2% of human cases of TB in the U.S. are due to M. bovis infection, and most are related to exposure to M. bovis in a country where the disease is common in animals.
• Human TB due to M. bovis was once common in the U.S., but was greatly reduced by efforts to control the disease in cattle and routine pasteurization of cow's milk.

• For all species, the signs and symptoms of TB disease depend on where in the body the TB bacteria are growing.  
• Symptoms of TB disease will vary depending on the part of the body that is affected.
• People and animals can be infected with TB bacteria and not have any symptoms (called latent TB).

Human Signs & Symptoms

• When the lungs are infected, symptoms can include:
  • A bad cough that lasts for 3 weeks or longer
  • Pain in the chest
  • Coughing up blood or phlegm from deep inside the lungs
• Other symptoms can include:
  • Weakness or fatigue
  • Weight loss
  • Loss of appetite
  • Chills
  • Fever
  • Sweating at night

Livestock Signs and Symptoms

• Center for Food Security & Public Health:  Bovine Tuberculosis Fact Sheet

Wild and Captive Deer and Elk Signs and Symptoms

• Michigan Department of Natural Resources Wildlife Disease Manual-Bovine TB Topic

Human Testing & Diagnosis

• There are two kinds of tests to detect TB bacteria in humans:
  • TB skin test (TST)
  • TB blood test
• A positive skin test or blood only indicates a person has been infected with TB bacteria.
• A Latent TB infection (LTBI) is when a person has been exposed to TB but is not experiencing illness.
• Active TB is when a person has been exposed to TB and is experiencing TB disease.
• Following a positive skin or blood test, additional tests, such as a chest x-ray and sample of sputum are needed to determine if the person has TB disease.

Livestock Testing & Diagnosis

• United States Department of Agriculture TB Control and Eradication Program
• Michigan Department of Agriculture and Rural Development - Bovine TB Program

Wildlife Testing & Diagnosis in Michigan

• The heads and/or lungs of deer are examined by Michigan Department of Natural Resources Wildlife Disease Laboratory biologists.
• If lesions suspicious for Bovine TB are seen in selected lymph nodes or other organs, tissues are collected for further testing.
• Microscopic examination of tissues using special stains to detect Mycobacterium organisms is done at Michigan State University Veterinary Diagnostic Laboratory.
• Suspect tissues are also submitted to the Michigan Department of Health and Human Services Bureau of Laboratories for mycobacterial culture and identification.
• Bovine TB positive samples from deer are then submitted to the United States Department of Agriculture's National Veterinary Services Laboratory for genetic analysis.

MDNR Wildlife Disease Manual:  Bovine Tuberculosis

Prevention/Control Methods for People

• TB can spread through the air when a person with TB disease of the lungs coughs, speaks, or sings.  People nearby may breathe in the bacteria and become infected. 
• People who are potentially exposed to TB can be skin-tested to determine if they are infected with TB.
• These tests can be done at either the local health department or a private physician's office.
• A positive skin test, however, does not identify the type or source of the infection.
• People who test positive must undergo additional evaluation to determine if they have latent TB or TB disease.  Both types of TB require treatment with special medications for weeks to months.
• Remember, most people get the infection from other people.
  • In Michigan, people who work with livestock or wild deer in certain areas of the state (Northeastern Lower Peninsula) are at higher risk for exposure to Bovine TB.
  • People who work with animals at high risk for Bovine TB should take appropriate precautions including wearing gloves when field dressing deer or handling deer carcasses.

Prevention/Control in Livestock

• In the early 1900's, the federal government instituted an eradication program for bovine TB.
• This program includes testing of livestock on farms and monitoring of animals sent to slaughter or transported across state lines.
• As a result of this program, bovine TB been greatly reduced in cattle in the U.S.
• In Michigan, there is an ingoing effort to eliminate Bovine TB in both wildlife and livestock.

Prevention/Control in Wild Deer

• There are no effective vaccines for disease prevention and no effective medications for treatment of bovine TB in wild deer.
• A combination of wildlife disease surveys and deer management strategies are being used to eliminate the disease in wild deer.
• The wildlife surveys monitor the spread and occurrence of the disease.

Human TB Case Surveillance Information

• Reported Tuberculosis in the United States, 2020
• MMWR-Notes From the Field:  Zoonotic Mycobacterium bovis in Deer Hunters--Michigan, 2002-2017
• Emerging Infectious Diseases Journal:  Human Mycobacterium bovis Infection and Bovine Tuberculosis Outbreak, Michigan, 1994-2007

Domestic Animal TB Surveillance Information

• TB Brucellosis Summary Reports and Affected Herd Maps by Year -USDA
• Michigan Bovine Tuberculosis Zones

Wildlife TB Surveillance Information

• Michigan Department of Natural Resources - Bovine TB Information

For information regarding specific questions about the effects of TB on wildlife, domestic animals, or humans, consult one of the agencies listed below:

Michigan Dept of Agriculture & Rural Development 
Animal Industry Division
Constitution Hall, 6th Floor
PO Box 30017
Lansing, MI 48909
800-292-3939

Atlanta Regional Office
16860 M-32
PO Box 758
Atlanta, MI 49709
989-785-5616

Michigan Dept of Health & Human Services
Bureau of Epidemiology and Population Health
333 S Grand Ave
PO Box 30195
Lansing, MI 48909
517-335-8165

Michigan Dept of Natural Resources 
Wildlife Disease Lab
4125 Beaumont Rd
Lansing, MI 48910
517-336-5030

Michigan State University Extension 
Large Animal Sciences / Beef
A100 Vet Medical Center
East Lansing, MI 48824
517-432-1494

Northeast Region / Dairy
101 S Court St
PO Box 69
Mio, MI 48647
989-826-1160

U.S. Dept of Agriculture - Veterinary Services
3001 Coolidge Rd, Ste 325
East Lansing, MI 48823
517-324-5290

U.S. Dept of Agriculture - Wildlife Services 
2803 Jolly Rd, Ste 100
Okemos, MI 48864
517-336-1928

Gaylord Regional Office
1865 O'Rourke Blvd, Ste C
Gaylord, MI 49735
989-705-8467