Paratuberculosis - current concepts and future of the diagnosis

Intra-vitam diagnosis of paratuberculosis is performed either directly by detection of the causative agent, or indirectly by measurement of immune reactions. The detection rate of diagnostic methods is largely dependent on the state of the disease in infected animals. Direct identification of Mycobacterium avium subsp. paratuberculosis in faecal samples is limited by biological factors (shedding of low amounts of bacteria, intermittent shedding, clumping) and methodological influences. The presence of ubiquitous nonpathogenic mycobacteria in the environment of farm animals can impair the specificity of indirect tests. Up to now, none of the diagnostic procedures available enables a reliable diagnosis of paratuberculosis on the individual animal level. Estimation of prevalence is also complicated. Enormous research efforts are taking place to improve existing and to develop novel diagnostic procedures for paratuberculosis. However, control of the disease is possible even now by combining regular diagnosis with strict sanitary measures and removal of identified infected animals.