Mycobacterium Avium Paratuberculosis: A Disease Burden on the Dairy Industry

SIMPLE SUMMARY: The causative agent of Johne’s disease is Mycobacterium avium paratuberculosis, a virulent contagious bacterial species. At present, Johne’s disease is an endemic disease of beef and dairy farming. This disease incurs serious economic costs and creates animal welfare issues in food production. Disease management is often ineffective due to poor diagnostic techniques, subclinical infections, high fecal shedding, vertical transmission, and lack of producer awareness. Furthermore, foodborne transmission and a correlation with human inflammatory bowel disease further strengthen the importance of this pathogen. Harmonized effective biosecurity measures and timely culling of high-shedding animals are essential in limiting the spread of disease. At farm level, this is not always implemented, however, as producers often do not recognize the importance of Johne’s disease at production level. To improve animal welfare and ensure public health safety, it is imperative to better understand the factors promoting Mycobacterium avium pathogenicity and virulence. ABSTRACT: Mycobacterium avium paratuberculosis is responsible for paratuberculosis or Johne’s disease in cows, having economic impacts on the dairy industry and a prevalence rate exceeding 50% in dairy herds. The economic burden of Johne’s disease relates to decreased milk production and costs of disease prevention, treatment, and management, while having an economic impact on dairy producers, processors, consumers, and stakeholders of the dairy industry. Determining the true economic impact of the disease is difficult at regional and farm level as symptoms are not evident in subclinically infected animals. At present, the virulence, pathogenicity, persistence, and infectious dose of M. avium paratuberculosis are poorly understood, consequently effective paratuberculosis control measures remain obscure. M. avium paratuberculosis is potentially zoonotic with foodborne transmission a public health risk due to a possible causative link with inflammatory bowel disease in humans. A preventive approach is necessary to reduce the presence of this drug-resistant pathogen in dairy herds and subsequently dairy food. The use of inefficient diagnostic tests coupled with the long latency period of infection results in delayed animal culling and trade of asymptomatic animals, leading to regional transmission and increased disease prevalence. To date, there has been limited success at controlling and treating this terminal endemic disease, leading to significant prevalence rates. This study aims to outline the key factors associated with Johne’s’ disease while outlining its significant impact on the dairy sector.