Mycobacterium avium subspecies paratuberculosis Infection in Ruminants: Agent, Disease, Diagnosis, and Control

This reprint is a collection of recent research on paratuberculosis, a hidden killer of ruminants and farms. Creeping into a herd silently, the infectious agent Mycobacterium avium ssp. paratuberculosis (MAP) moves from adults to youngstock and may get the upper hand after several years. More and more cachectic animals with non-treatable diarrhea and a significant drop in milk yield or daily gain keep farmers awake at night. It is hard to decide what to do when the veterinarian has diagnosed paratuberculosis, also called Johne's disease. The disease came in slowly, and-in case of an adequate disease control plan-will leave slowly. The biology of the agent, a complicated pathogenesis, and the resulting difficulties in diagnosing the infection in live animals make efficient control plans challenging. Growing farms worldwide are more prone to severe health problems due to paratuberculosis than smaller ones. Decades of research led to an increase in knowledge that enabled progress to be made in control programs. But the philosopher's stone is still not found. This reprint presents recent research on different aspects of paratuberculosis and MAP, such as the spread of the organism between and within herds, risk factors in biosecurity and farm management, molecular diversity, co-pathologies, and the interaction of MAP with the host and the gut microbiome. State-of-the-art diagnostic approaches, including environmental sampling and machine learning techniques, complement the selected studies. Special emphasis is given to paratuberculosis in small ruminants, which is of growing importance worldwide.