TB poster.pdf (BTP) (click link to access poster)

  • Cause of bovine tuberculosis in South Africa

 BovineTB.jpg
Lung lesions in an African buffalo
with bovine tuberculosis
Tuberculosis is a chronic, primarily respiratory disease which can affect all mammals including humans. It is caused by either of two bacteria of the genus Mycobacterium namely, Mycobacterium tuberculosis generally associated with human tuberculosis, and Mycobacterium bovis, the agent that cause tuberculosis in animals, generally known as bovine tuberculosis (BTB).

 
Lymph node abscess due to
infection with Mycobacterium bovis in a kudu

  • History

Bovine tuberculosis caused by Mycobacterium bovis was most probably introduced to South Africa by European settlers and their cattle. In South Africa, bovine tuberculosis was first reported in 1880 in domestic cattle and in 1928 in wildlife in the Eastern Cape. Soon after the introduction of the "National Tuberculosis and Brucellosis Eradication Scheme" in 1969, bovine tuberculosis could be successfully controlled in commercial cattle herds. Bovine tuberculosis is a serious threat to livestock and wildlife species and is therefore controlled in many countries including South Africa, and African buffalo (Syncerus caffer) is the wildlife maintenance host. A better understanding of transmission patterns and distribution of the disease will permit more precise targeting of control measures that will potentially benefit both wildlife and livestock Molecular typing techniques are useful tools that can be applied to bovine tuberculosis epidemiology in order to underpin control of the disease. These techniques are now applied in the Tuberculosis laboratory and offered as a service.

  • Future prospects

Under the present budgetary constraints, effective control of bovine tuberculosis becomes increasingly difficult. The situation can in future be further complicated by the potential spillover from wild animals to livestock. If bovine tuberculosis can establish itself in a free ranging (small) mammal species which can bridge the wildlife-domestic animal interface, recurrent infections in cattle will be inevitable. Similar situations are known from Ireland, United Kingdom and New Zealand. In many countries, eradication of bovine tuberculosis from cattle and wildlife reservoirs is far out of reach. The development of vaccine in the future remains the only feasible long term solution in all ecosystems where a wildlife reservoir maintains the infection.

  • Vision of the TB Laboratory

To hold the status of an advisory body to the Directorate of Veterinary Services of the Department of Agriculture, Forestry and Fisheries (DAFF) with regard to bovine tuberculosis and other mycobacterioses and to become an international reference laboratory for animal tuberculosis.

  • Activities in the TB Laboratory
  • Diagnostics

  • Research

  • Production and sale of fortuitum PPD used in the diagnosis of Tuberculosis in buffaloes and cattle

  • Buffalo Test Package

  • Diagnosis

The following diagnostic services are offered:

  • Gamma Interferon assay

  • Ziehl Nelsen staining and Microscopy (smear examination)

  • Blood processing for Gamma Interferon assay (within 8 hours of collection)

  • Mycobacterium spp. culture and identification

  • Differentiation of M. tuberculosis complex species by PCR

  • Molecular typing of M. bovis

  • Molecular typing of M. tuberculosis

  • Isolation and identification of Mycobacterium avium subspecies paratuberculosis

  • Johne's disease ELISA

  • Fortuitum PPD sales

 
M. bovis isolates on Löwenstein-Jensen slopes

PCR.jpg 

Analysis of polymerase chain reaction (PCR) results

Production and sale of Fotuitum PPD (Purified Protein Derivative)

During the evaluation of the "gamma Interferon assay" in cattle and African buffalo we found that the tests produced false positive reactors in approximately 4% of samples tested. Research into the cause of the non-specific reactions led to the conclusion that animals harboring certain environmental mycobacteria, mostly of the M. fortuitum complex, become sensitized to bovine and avian tuberculin PPD resulting in some of these animals showing false positive reactions in the commercial Bovigam® assay. Following its modification into a triple comparative test by including a crude antigen mixture prepared from M. fortuitum a high specificity of > 99% was achieved. The Fortuitum antigen is offered for sale at the Tuberculosis Laboratory in ampoules containing 375µl dose each, enough to test 15 animals.

Training in Laboratory Procedures relevant to the "gamma interferon assay"

Over the last years, the gamma interferon assay has established itself as the most widely used test in the diagnosis of bovine tuberculosis in buffalo. One of the major constraints, however, is the necessity for processing the blood samples within eight hours. To overcome this problem, private and provincial laboratories were given the protocol and are trained to perform blood processing (First stage of Gamma Interferon Test). Plasma samples are then sent to the laboratory ready for stage two of Gamma interferon test.

Important hints for the submission of specimens

  • Specimen collection for culture isolation
  • specimen is part of the affected area

  • at least 5 grams where possible

  • any contamination should be avoided

  • Blood collection for Gamma Interferon assay
  • Collect 10 ml blood in heparin per animal

  • Keep blood at ambient temperature (optimum: 15 – 25ºC) during transport

  • Submit blood to the laboratory within 8 hours after collection
  • Packaging for transport

  • avoid cross contamination of specimens

  • pack in safe containers

  • PREVENT ANY LEAKAGE!!

  • label correctly (sender, owner, species, animal ID, specimen type, date of collection, examination required, history)

  • maintain cold chain during transport of tissue samples

_________________________________________
>>>Back to Tuberculosis Laboratory