Ovine Johne's disease
What is Johne’s disease?
Johne’s disease is caused by the bacteria Mycobacterium avium paratuberculosis (MAP), and can affect sheep, cattle and deer. Bacterial infection alone does not always lead to clinical disease. It could be that an external trigger (such as environmental stress) may also be required for clinical disease to develop (see diagram).
The bacteria can be spread via faeces, in utero, through colostrum and milk, or by contact between the mother and offspring. The faeces of infected animals often contaminate pastures and waterways, spreading the infection to other stock on the property. The bacteria is hardy and can survive for anywhere between three and eighteen months on pasture.
Additional information regarding Johne’s disease can be found on the JDRC website.
Click below to hear Professor Richard Whittington (University of Sydney) discuss the diagnosis, control and management of Johne's disease on a Red Meat Profit Partnership conference call.
As part of the NZSTX project, The New Zealand Merino Company (NZM) and the Ministry for Primary Industries co-funded an ovine Johne's disease (OJD) study run by the Johne’s Disease Research Consortium (JDRC).
The aim of the project was to better understand the impact of OJD on New Zealand sheep farms and to determine the value of tools such as vaccination to manage the disease. The study concluded that vaccination is cost-effective on farms with regularly observed clinical levels of OJD.
Click here for the Beef + Lamb New Zealand fact sheet on managing Johne's disease in sheep.