The specificity of phage testing for MAP — where might it fit into the diagnostic armoury?

The current individual tools available for the diagnosis of Johne's disease are far from suitable to tackle this endemic disease. Culture, polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) tests, when used together can be useful in managing the disease in the later stages of infection at a herd level. They are, however, ill-suited to detecting the causative agent Mycobacterium avium subsp. paratuberculosis (MAP) at the early stages of infection and at an individual level. Phage technology offers another tool in the attempt to better manage and control this disease. Phage-technology has been demonstrated to rapidly and sensitively detect and specifically identify viable MAP in the milk and blood of cattle. Although in relatively-early stages of development phage technology offers a strong addition to the armoury of tests used to detect MAP in blood and milk, and may go on to be part of ongoing control measures to reduce the burden of disease to farmers and veterinarians