Control of footrot in small ruminants in Nepal - vaccination and sero-surveillance

• Lumle Agricultural Research Centre, Nepal
• NSW Agriculture, Australia

Most of the 19 million residents of Nepal are engaged in subsistence farming, therefore, it is of national importance that the country's sheep and goats are in good health. However, footrot was introduced by imported sheep in the 1960s. No control was attempted until 1975, by which time footrot had become endemic to three districts.
Footrot is a contagious bacterial disease which is transferred from hoof to hoof via wet soils and pastures. Affected animals may have lesions on the foot, lose large amounts of body weight and produce little fleece of inferior quality. As a result, meat per carcase, yields of wool, shepherds incomes, manure available to fertilise crops and pastures are all affected. In addition, animals cannot migrate to alpine pastures in spring and back to the villages in autumn. This upsets village practice of growing and harvesting crops while the stock are away.

In this project, reseachers from Lumle Agricultural Research Centre in Nepal and the University of Sydney, will try to eliminate mild footrot. They plan to again immunise animals with vaccines specific to these intermediate strains of Dichelobacter nodosus. Less virulent strains are a nuisance, especially in Australia, because they are difficult to eradicate by conventional methods such as footbaths, hoof paring, or vaccines prepared from a mixture of serogroups. Their presence is often invisible, yet in suitable conditions they may cause serious footrot outbreaks.

Researchers know that evidence of D. nodosus can apparently disappear from an area, only to reappear two seasons later. The present study will assess if the virulent strains have been eliminated or merely suppressed in Nepal. Vaccination will cease on flocks that have been previously vaccinated. If no clinical or bacteriological signs are found of the virulent strains it will be presumed eradicated. The findings will be added to a database of health records for about 10,000 Nepalese ruminants, collected over eight years.
In July and August, when the disease is most prevalent, researchers will look for evidence of benign footrot in areas of Nepal where it is not endemic. Samples will be collected and analysed for D. nodosus from flocks that can be accessed during these two months. Researchers will identify and vaccinate against the strains involved in mild footrot, both in Nepal and in six Australian flocks.
Throughout the project, the researchers will also look out for ruminant diseases and parasites such as brucellosis and hydatids that can infect humans.