Bovine Tuberculosis in a Nebraska Herd of Farmed Elk and Fallow Deer: A Failure of the Tuberculin Skin Test and Opportunities for Serodiagnosis

Table 1

History of herd and timeline of the outbreak investigation.

Action	Date	Number of animals
		Elk	Fallow deer
Original herd size	2008	60	50
SCT performed	March 2008	50 (all negative)	Not tested
Index case detected	January 30, 2009	1	0
SCT performed^a	February/March 2009	42/59 tested (3 true positive, 25/39 false negative*)	Not tested
Postmortem examinations^b	June 2009	52	48
Serum collected	June 2009	34/52 examined	32/48 examined
Apparent prevalence^c	June 2009	75% (40/53 TB positive)	71% (34/48 TB positive)

^aOnly 42/59 elk and none of the fallow deer were tested by SCT primarily due to animal handling and management issues. All of the elk that were tested by SCT were examined postmortem.
^bHerd depopulation completed; however, not all of the carcasses were examined.
^cThe apparent prevalence includes the index case and is based upon the number of animals with mycobacteriosis compatible gross and microscopic lesions and/or M. bovis isolated from tissues.
*Necropsies were performed 3 months after SCT; thus, values may underestimate the true false negative rate.