Epizootic of paratuberculosis in farmed elk.

After multiple cases of chronic diarrhea and weight loss in a farmed elk herd, 3 yearlings and 1 adult elk with similar clinical signs were euthanatized and necropsied. Gross and histologic evidence of paratuberculosis were found in the yearlings. Evidence of serum antibody to Mycobacterium paratuberculosis was detected in the 2 elk with the most disseminated infection. Acid-fast organisms were isolated from multiple organs in all 4 elk and identified as M paratuberculosis by DNA probe. Thirty-five percent of 1 calf crop (n = 31) died or were euthanatized because of paratuberculosis before they were 2 years old. The organism was believed to have been spread by standing water that was used by calves as a wallow and a source of drinking water. The water was believed to have been contaminated by an infected adult female elk introduced to the herd just before calving season.