How common is Johnes disease in dairy cattle?
A 1996 national survey in the U.S. estimated that 22% of U.S. dairy herds are infected. The full survey report can be found at: http://www.aphis.usda.gov/vs/ceah/cahm/Dairy_Cattle/johnsart.htm The U.S. rate of dairy herd infection is similar to that reported in other countries using similar tests: Netherlands (55%), Belgium (22%), Austria (7%), England and Wales (17%), Denmark (47%), New Zealand (60%) and the state of Victoria in Australia (22%). The herd infection rate in U.S. beef cattle is lower although not many surveys have been reported. A 1997 survey in the U.S. found that: 7.8% of beef herds were infected using the same survey methods as for dairy cattle. Infection rates in beef cattle a most likely lower than in dairy cattle due to differences in animal husbandry practices.
