Pathogen Safety Data Sheet - Bovine Tuberculsosis

---

SECTION I: DISEASE / INFECTIOUS AGENT

SYNONYM / CROSS REFERENCE: TB, tuberculosis, mycobacteriosis

ETIOLOGY / TAXONOMY :

Genus: Mycobacterium
Species: bovis
Other mycobacterial species such as tuberculosis, microti and africanum may cause mycobacteriosis in animals.

ORGANISM CHARACTERISTICS: ⁽¹⁾

• acid-fast, gram positive, non-motile, obligate aerobes, pleomorphic rods 0.2- 0.6 µm in diameter and 1.5- 3 µm in length
• slow growing (colonies appear on Lowenstein-Jensen culture medium in 2-8 weeks)
• hydrophobic with high lipid content in cell wall. Cell wall resists decolourization in staining (acid fast). Ziehl-Neelsen or Kinyoun staining techniques with carbol fuchsin most widely used.

SURVEILLANCE :

Bovine tuberculosis is a reportable disease in Canada. Animal owners, veterinarians and laboratories are required to immediately report the presence of an animal that is contaminated or suspected of being contaminated to a CFIA district veterinarian. Control or eradication measures will be applied immediately (http://laws.justice.gc.ca/en/H-3.3/fulltoc.html).

DISTRIBUTION :

Bovine tuberculosis is diagnosed worldwide with great variations in incidence between regions and countries. ⁽²⁾ It has been eradicated from all Canadian livestock herds, including Manitoba's Riding Mountain National Park, which had been the only part of Canada without TB-free status. Freedom of Canadian livestock from M. bovis is confirmed by slaughterhouse inspection surveillance.

SECTION II: ANIMAL HEALTH HAZARD AND EPIDEMIOLOGY

CLINICAL DISEASE / PATHOGENESIS :

Many infected animals can appear healthy but lesions may be found post mortem. ⁽³⁾ Other possible signs are progressive emaciation, poor appetite, fluctuating temperature, respiratory distress, pharyngeal obstruction, reproductive disorders and mastitis. ⁽⁴⁾

1. The infectious dose may be as low as a few organisms by inhalation in animals, but exposure does not always result in disease. The risk of infection is greater in enclosed areas such as barns or where animals congregate such as feeding areas.
2. The incubation period is usually 2-6 months, however dormant infections can last a lifetime in both humans and animals and may reactivate during periods of stress or in old age. ⁽¹⁾

SOURCE / MODE OF TRANSMISSION / COMMUNICABILITY : ⁽⁴⁾

• inhalation (aerosols or droplet nuclei)
• ingestion (infected milk, drinking water and feed)
• excretion (sputum, mucus, feces, milk, urine, vaginal and uterine discharges)

VECTORS : none

HOST RANGE : ⁽⁴⁾

• all warm-blooded vertebrates (cattle, goats and pigs most susceptible; sheep and horses show high natural resistance)

ZOONOTIC POTENTIAL : ^(5,6)

• M. bovis can be transmitted to humans.
• immunocompromised individuals are particularly at risk.

RESERVOIR : ^(4,5)

Maintenance reservoirs include deer, elk and bison (North America), buffalo (South Africa), water buffalo (Australia), badger (Meles meles) in the United Kingdom and brush-tail possum (Trichosurus vulpecula) in New Zealand.

Section III: DIAGNOSIS

NECROPSY / HISTOPATHOLOGY FINDINGS : ⁽⁴⁾

• Granulomatous lesions are most frequently found in lymph nodes (especially bronchial, retropharyngeal and mediastinal), liver, spleen, lungs, pleura, kidney and uterus and occasionally in myocardium, intestine, omentum, peritoneum, meninges, skin, mammary glands, genital tract and bone marrow
• Lesions may appear encapsulated, creamy, caseous or calcified.

LABORATORY DIAGNOSIS : ⁽⁵⁾

• in live cattle, tuberculin skin test (caudal tail fold) If positive, followed by the Comparative Cervical Test (CCT)
• post mortem, culture (special growth requirements) of lesion and surrounding tissue
• DNA Probe/PCR
• formalin-fixed tissue samples for histological diagnosis

DRUG SUSCEPTIBILITY : ^(3,7)

Treatment of animals is rarely practical. Humans can be treated with a combination of antimicrobials such as Rifampin, Isoniazid, Ethambutol and Pyrazinamide for at least 6-9 months.

DIFFERENTIAL DIAGNOSIS : ⁽⁵⁾

The following diseases may show clinical similarity to bovine tuberculosis:

• lung abscess due to aspiration pneumonia
• pleurisy and pericarditis following traumatic reticulitis
• chronic contagious bovine pleuropneumonia
• upper respiratory disease
• actinobacillosis
• bovine leukosis
• lymphadenopathy
• other causes of mastitis

SECTION IV: DECONTAMINATION PROCEDURES

Select a registered disinfectant with a drug identification number (DIN). Use according to label directions for concentration and contact time. Consider organic load and temperature. It is recommended that laboratories evaluate the effectiveness of the disinfectant using a validated method (eg. Quantitative Carrier Test). See table 1 to help select a registered disinfectant for use against M. bovis.

Table 1: Active ingredients considered to be effective against M. bovis ⁽⁸⁾

PHYSICAL INACTIVATION : ⁽⁷⁾

• steam sterilization, incineration, ultraviolet radiation

SURVIVAL OUTSIDE OF HOST : ⁽⁷⁾

M. bovis can survive in the environment and diagnostic specimens for weeks (longer in cold, dark and moist conditions).

SECTION V: LABORATORY HAZARDS FOR HUMANS

LABORATORY-ACQUIRED INFECTIONS: ⁽⁹⁾

Most references refer to human tuberculosis (fourth most frequently reported laboratory-acquired infection) , not bovine tuberculosis. Low infectious dose and long incubation period are of concern.

BIOSAFETY PRECAUTIONS : ^(7,9)

• inhalation of aerosols (created by infected animals, their bedding or excretions, from aerosol generating procedures, handling heat-fixed smears or cultures, or preparation of frozen sections, especially from undiagnosed cases).
• ingestion
• accidental injection

SECTION VI: PHYSICAL AND OPERATIONAL REQUIREMENTS

CONTAINMENT REQUIREMENTS :

Primary culture and identification of diagnostic specimens is to be performed at Level 2 physical containment provided that Level 3 operational requirements are carried out. All other manipulations, including further identification and sensitivity testing, must be carried out using Level 3 physical and operational requirements as per the Containment Standards for Veterinary Facilities.
The Standards can be accessed at : http://www.inspection.gc.ca/english/sci/lab/convet/convete.shtml

PERSONAL PROTECTIVE EQUIPMENT :

Laboratory :

• primary layer of dedicated laboratory clothing (e.g. scrubs and head cover) and dedicated laboratory footwear should be worn.
• secondary layer of protective clothing (e.g. solid-front gowns with tight-fitting wrists, 2 pairs of gloves) should be worn over laboratory clothing when directly handling infectious materials.
• adequate respiratory protection should be worn when directly handling infectious material outside BSC.
• when full body protective clothing is not worn a shower is required on exit; where a known or suspected aerosol exposure has occurred a shower is required on exit.

Post Mortem :

• primary layer of dedicated laboratory clothing (e.g. scrubs and head cover) and dedicated laboratory footwear should be worn.
• secondary layer of protective clothing should be worn over laboratory clothing when directly handling infectious materials.
• cut resistant gloves, adequate respiratory protection, steel toed/steel shanked rubber boots.
• a shower is required on exit

HANDLING INFORMATION :

Spills in laboratory :
Spill protocol must be in place and include the following scenarios:

• spills inside the Biological Safety Cabinet (BSC)
• spills outside the BSC
• spills while performing aerosol generating procedures
• Consider entry and exit procedure modifications if necessary, appropriate PPE, disinfection of spill and surroundings including contact time, flow (pattern) of the clean up and disposal of contaminated materials.

Refer to Table 1 for disinfectant selection.

STORAGE : All cultures and infected material should be stored in leakproof, sealed containers that are accurately labeled and clearly identified as a biohazard risk. The access to infectious material should be controlled at all times. Records must be kept to describe the use, inventory and disposal of infectious material.

DISPOSAL : Decontaminate all infectious material prior to disposal. Use steam sterilization, incineration or chemical disinfection.

REFERENCES:

1. Thoen C, Williams D, Tuberculosis, Tuberculoidoses, and other Mycobacterial Infections In: Beran GW, ed Handbook of Zoonoses, Second Edition, CRC Press, 1994:41-59
2. Zoonoses and Communicable Diseases Common to Man and Animals, Second Edition, PAHO publication # 503
3. Bovine Tuberculosis Fact Sheet, U.S. Department of Agriculture, updated August 2002, http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_ahtb.html
4. Radostits OM, Gay CG, Blood DC, Hinchcliff KW, Veterinary Medicine, Ninth Edition,W.B. Saunders Company Ltd. 2003:909-934
5. Bovine Tuberculosis Fact Sheet - PDF (119 kb), OIE Collaborating Center, Iowa State University College of Veterinary Medicine, updated 2003-06-03, http://www.cfsph.iastate.edu/Factsheets/pdfs/bovine_tuberculosis.pdf
6. Bovine Tuberculosis Fact Sheet, Animal Health CFIA, updated 2003-08-12, http://www.inspection.gc.ca/english/anima/disemala/tuber/tbfse.shtml
7. Mycobacterium tuberculosis, Mycobacterium bovis, MSDS, Health Canada, updated 2001-05-15, http://www.phac-aspc.gc.ca/msds-ftss/msds103e.html
8. Lauzardo M, Rubin J, Mycobacterial Disinfection In: Block SS, ed. Disinfection, Sterilization and Preservation, Fifth Edition, Lippincott Williams and Wilkins, 2001:513-528
9. Collins CH, Laboratory-Acquired Infections, Third Edition, Butterworth-Heinemann Ltd. 1993

LAST UPDATED (DATE): May 9, 2005
PREPARED BY: The Biohazard Containment and Safety Unit, CFIA

Disclaimer: Although the information and recommendations in this Pathogen Safety Data Sheet are compiled from reliable sources, there is no guarantee, warranty or any assurance that the information and recommendations are correct, accurate, sufficient, reliable or current and the Canadian Food Inspection Agency shall not be responsible for any loss or damage resulting from or in connection with the use of or reliance upon the information and recommendations.

The user assumes all risks and responsibility for and shall be liable for the use of and any reliance on the information and recommendations and the results thereof and any loss or damage resulting therefrom.

• Main Page - Bovine Tuberculosis