Container: Sterile container
Collection protocol: Faeces collected per rectum using single use disposable gloves and faeces placed in sterile container. Up to 5 faecal samples can be pooled in the laboratory prior to testing.
Special handling/shipping requirements: Samples are to be transported and stored chilled. Do not freeze samples.
General information about the disease: Johne’s disease is caused by an infection with the bacterium Mycobacterium avium paratuberculosis (MAP) of the gut in cattle and other ruminants. Gradual thickening and inflammation of the intestinal wall eventually prevents uptake of nutrients. Clinical Johne’s disease is characterised by ill-thrift, progressive weight loss and profuse diarrhoea. No cure is available and the condition is eventually fatal. Calves and young stock are particularly susceptible to infection. However, the disease has a very long ‘incubation period’ so that clinical signs of Johne’s disease typically appear several years later in the adult cow. Shedding of Johne’s bacteria (primarily in faeces) also increases with age and advanced stage of infection. Shedding may be intermittent during early stages of the disease so faecal samples may need to be taken at intervals (e.g. every 6months) and tested.
Comparison with other related tests: Mycobacterium avian paratuberculosis culture is undertaken by reference laboratories and the organism can take up to 16 weeks to grow. Ziehl-Neelsen (ZN) staining of faecal or ileocaecal valve mucosal smears is no longer recommended. Various serological test are available for diagnosis including ELISA, complement fixation test (CFT) and agar gel immunodiffusion test (AGID). The ELISA and CFT are useful for confirmation of infection of clinically affected animals. The semi-quantitative PCR has an advantage in that it is a rapid test used to detect the presence of the organism and to assess the degree shedding from an animal.