Wet weather increases risk of Johne’s disease

Cases of Johne’s disease could increase this year as a result of wet soil conditions following a washout 2012.

Acidic, wet soils with high iron and organic matter content increased the risk of the disease spreading, said Rupert Hough from the James Hutton Institute, speaking at the recent Quality Meat Scotland research and development conference in Dundee.

“Animal disease control measures and best practice health schemes are quite successful, but they don’t seem to work all the time; the soil environment plays a significant role in disease prevalence,” he said.

Drawing on soil sampling research work across eight farms in Scotland, Dr Hough said 75% of the soil samples taken from the farms tested positive for the organism that causes Johne’s – mycobacterium avium paratubercluosis (MAP).

In the right soil conditions, the organism could survive for up to three years. But in dry soil areas that were more alkaline, the organism could live in soil for less than a year, he added.

In addition, he said there was a chance the bacteria could be transferred from the soil to straw and silage, although more work needed to be done to ascertain the risk of this on farm.

To tackle the problem he urged producers to lime their fields where necessary, which would also encourage grass growth, and fence off wet patches, improve drainage and double fence around ditches and streams.

“Farmers used to lime quite regularly, but they stopped, so the soils are becoming more acidic and the incidence of diseases is spreading,” said Dr Hough.

There was also a risk of Cryptosporidium and live fluke spreading in a similar way, he warned.

“Lots of diseases are very hygiene-related. Cryptosporidiosis has been associated with wet areas, so there could be an increase in that as well this year,” he said.

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