Condition of Johne's disease among small ruminants

Background and Aim : Mycobacterium avium subspecies paratuberculosis (MAP) is a major pathogen that is unequivocally the cause of Johne's disease (JD) in domestic livestock, wild ruminants and other animal species, including primates. MAP bacteria multiply in the intestinal mucosa and are frequently excreted in feces, milk, and vaginal secretions from infected animals (atypical animals, sub-clinics and clinics). Newborns are most susceptible to infection and are generally infected in this first lifetime by oral ingestion of contaminated food, water or milk from their infected mothers. The incubation period for JD is long and variable depending on a number of factors such as environmental stress, nutrition, production, concurrent diseases, overcrowding, etc. Clinical cases may be readily detected to diagnose, however, it is difficult to diagnose the preclinical stages of the disease. Sub-clinically infected animals excrete MAP in faecals and milk, thus quietly spreading the infection to other animals in the herd by contaminating the environment. This “silent transmission” occurs over long periods of time before being disposed of from herds. Live MAP bacteria are found in pasteurized milk, milk product, and infant formula made from pasteurized milk. MAP is found in manure of animal origin that can be leached into surface water, cow manure in solid and liquid form that is implemented as fertilizer in agriculture. The existence of bacilli in tap water provides multiple transmission routes for the human population.Methods : JD has been reported to be widespread in different livestock species and in different regions of the world. We standardized and used principal antigen detection tests (microscopy, IS۹۰۰ PCR, Real-time IS۹۰۰ PCR, IS۱۳۱۱ PCR_RE) and antibody detection tests (dot ELISA, indirect ELISA, latex agglutination test) for diagnosis of JD.Results : Conventional methods of testing and slaughter have failed to control the propagation of the JD into small ruminant herds, although excretory animals have been eliminated. For sustainable goat and sheep farming, it is essential to monitor JD using the suitable diagnosis test and prevent the disease with an effective vaccine.Conclusion : With a view to preventing human infection, there is an urgent need to conduct comprehensive research to control and eradicate MAP in the domestic livestock population of the country.

کلیدواژه ها:

Domestic livestock ، Diagnosis ، John’s disease ، Milk and milk products