ELK: TRUE CASES & STORIES - JOHNE'S INFORMATION CENTER

Johne's disease outbreak in farmed elk*

A new elk raising facility was built early in the 1990s on land that had not housed livestock for more than 20 years. Eighty elk (Wapiti wapiti) were purchased from various herds in the United States and Canada. No unusual or extensive health problems were noted prior to the Johne's disease outbreak.

Photo of elk herd

One winter, a 3 year old female elk was introduced without quarantine into the herd. She suffered various ailments for the next 4 months, including lameness, weight loss and diarrhea. Several treatments for gastrointestinal parasites did not change the animal's condition. A complete blood count and chemistry panel were not diagnostic. The "Johne's test" requested by the veterinarian was negative (the diagnostic laboratory receiving the sample ran a complement fixation test). She was moved back and forth several times from a 16 acre group pen to a pen used to isolate sick Photo of elk cow animals. That spring she delivered a stillborn calf and acted as a "nursemaid" to the 31 calves born in the group pen. She died in early summer. Johne's disease was diagnosed at necropsy and confirmed by bacterial isolation of the organism from tissue samples.

Eleven of 31 calves born and held in a pen with the M. paratuberculosis infected adult cow developed severe clinical signs (emaciation and diarrhea) and died of Johne's disease before they reached 2 years of age. The status of the remaining 19 calves is unknown. Infection of the calves was thought to have Photo of a muddy wallow been through fecal-oral transmission of the organism via a muddy wallow frequented by both the calves and the infected adult. Cross-fostering by the infected adult may also have contributed to the infection, as more than one calf may have nursed from the cow.

Confirmation of the diagnosis of paratuberculosis was based on culture of tissues, serology and histopathology.

After a diagnosis of Johne's disease was made in the yearlings, the group pen became the quarantine site for any animals with signs of Johne's disease. After all the yearlings had left the premises, the soil in the pen was turned and the pen held empty for a year. This pen was then to be used solely for adult animals on the presumption that, as in cattle, mature elk will be less susceptible than young stock to infection from the few organisms that may have remained.

All the animals held in the pen (i.e. the cows of the affected calf crop) at the time of the outbreak plus resident bulls were tested one year after the outbreak in the yearlings. One fecal sample was collected from each adult animal; each sample was negative by the BACTEC culture method. A number of annual negative tests are necessary before confidently concluding that the remaining animals on the premises are free of M. paratuberculosis infection.

Case Lessons:

1.	Elk are susceptible to M. paratuberculosis infection, with clinical signs of disease appearing at a younger age in this outbreak than is typical for cattle.
2.	Microscopic lesions resembled those found in cattle and were characterized by granulomatous inflammation of ileum, jejunum and mesenteric lymph nodes.
3.	Pre-purchase herd testing is important to limit the likelihood of introducing the disease to uninfected herds.
4.	Johne's disease does not yet appear to be a common problem for the elk farming industry as a whole but the disease can be economically ruinous to individual herd owners.

*Summarized from:

Manning, E.J.B., H. Steinberg, K. Russow, G.R. Ruth, and M.T. Collins. 1998. Epizootic of paratuberculosis in farmed elk. J. Am. Vet. Med. Assoc. 213:13201322