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Bovine Tuberculosis

Bovine Tuberculosis, Image of deer in a field
  • Bovine tuberculosis (TB) is an infectious disease that is caused by the bacteria Mycobacterium bovis (M. bovis).
  • Bovine TB primarily affects cattle, however, other animals may become infected. 
  •  When M. bovis infects a human, it is often referred to as "Zoonotic TB", reflecting it's ability to infect both animals and humans.
  • Human TB is mostly caused by infection with the organism Mycobacterium tuberculosis.
  • Prior to the widespread practice of milk pasteurization, M. bovis was also a common cause of tuberculosis in people in the Western world.
  • M. bovis remains an important cause of human TB in the developing world, where people often live in close contact with their animals and consume products from them that are not first pasteurized. 
  • Bovine TB in animals and humans may infect the lungs, but may also infect the intestines and other parts of the body.
  • In Michigan, M. bovis infection can be found in free-ranging deer and cattle in certain parts of the state.
  • 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

    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

    Wildlife Testing & Diagnosis in Michigan

  • 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

    Domestic Animal TB Surveillance Information

    Wildlife TB Surveillance 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

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

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

    Michigan Dept of Natural Resources 
    Wildlife Disease Lab
    4125 Beaumont Rd
    Lansing, MI 48910

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

    Northeast Region / Dairy
    101 S Court St
    PO Box 69
    Mio, MI 48647

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

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

    Gaylord Regional Office
    1865 O'Rourke Blvd, Ste C
    Gaylord, MI 49735