Bovine Tuberculosis: A Review of Molecular Diagnostic Methods and Impact on Public Health

Abstract

Bovine tuberculosis (BTB) is a zoonotic infectious disease of cattle, other domesticated animals, and certain wildlife populations. It has been widely distributed throughout the world, and it has been a cause for great economic loss in animal production. In developed countries, the eradication programs have reduced or eliminated TB in cattle. Many factors contribute to the persistence of the disease, such as the limitations of diagnostic tests, larger herd sizes, increase in animal movements and trade, and limited options for control, such as restrictions on whole herd depopulation. The available advanced TB diagnostic techniques can detect and differentiate the causative mycobacterial species, and help an early confirmation of the diagnosis, which is useful to design appropriate control measures in the national BTB control programs. Molecular diagnostics, such as polymerase chain reaction, spoligotyping, restriction fragment length polymorphism (RFLP), variable number tandem repeats typing (VNTR), and polymorphism GC-rich repeat sequence (PGRS) are the techniques used for concurrent detection and typing of Mycobacterium species at the strain level. The molecular epidemiology is also being used to identify the source of contamination, to determine the risk factors of BTB transmissions, to investigate the drug resistance pattern, and to track the geographic distribution and spread of clones of Mycobacteria species. The molecular diagnosis is the tool to check whether active transmission or reactivation of BTB, hence, it is better to adopt these methods for the epidemiological survey of BTB. Since BTB is a major public health problem, at least a single reference laboratory should be available for molecular based diagnosis as part of its control.