Epidemiology, diagnostics, and management of tuberculosis in domestic cattle and deer in New Zealand in the face of a wildlife reservoir

Figures & data

Table 1. Disease metrics for infection with Mycobacterium bovis over three different time periods for cattle herds located in Vector Risk Areas and Vector Free Areas.

	Annual infected herd period prevalence (%)			Herd breakdown rate per 1,000 herds^a			Change of status to non-infected herd (%)
Vector area status	1992/93	2000/01	2011/12	1992/93	2000/01	2011/12	1992/93	2000/01	2011/12
Vector Free Area	1.3	0.3	0.06	6.8	1.6	0.04	68	66	86
Vector Risk Area	14.9	5.8	0.8	50.3	17.1	3.0	32	57	53
Total	3.6	1.3	0.18	13.4	4.4	0.3	42	58	57

^aTotal number of cattle herds for 1992/93, 2000/01 and 2011/12 were approximately 63,000, 69,000 and 66,000, respectively (P. Livingstone¹, pers. comm.)

Table 2. Summary of the frequency of and parameters used for diagnostic screening of cattle for infection with Mycobacterium bovis and the required movement controls for each of the different categories of control area and also for individual infected herds.

Movement Control Area	Cattle ≥3 months of age CFT tested at 1-year intervals; CFT cut-off of any visible or palpable swelling
	Ancillary blood testing of intradermal test reactor animals using the standard PPD IFN-γ test
	Pre-movement testing, CFT within 60 days prior to movement
Special Testing Annual Area	Cattle ≥12 months of age CFT tested at 1-year intervals, depending on risk; CFT cut-off of any visible or palpable swelling
	Ancillary blood testing of intradermal test reactor animals using the standard PPD or Special antigen IFN-γ test
	No movement testing
Special Testing Biennial Area	Cattle ≥24 months of age CFT tested at 2-year intervals, depending on risk; CFT cut-off of any visible or palpable swelling
	Ancillary blood testing of intradermal test reactor animals using the standard PPD or Special antigen IFN-γ test
	No movement testing
Surveillance Area	Dairy cattle ≥24 months of age and a sample of up to 250 beef cattle ≥24 months of age per herd or if less than 250 cattle per herd all cattle ≥24 months of age CFT tested at 3-year intervals; CFT cut-off of either; any visible or palpable swelling (standard interpretation) or ≥4 mm (modified interpretation)
	Ancillary blood testing of intradermal test reactor animals using the standard PPD or Special antigen IFN-γ test
	No movement testing
Infected Herd	Dairy cattle ≥6 weeks and beef cattle ≥3 months of age are CFT tested. CFTs must not be undertaken less than 60 days apart. To qualify for a change in status from infected to non-infected, CFTs must be at least 6 months apart and CFTs must be negative, or negative in subsequent follow-up IFN-γ tests or M. bovis culture of tissues. An additional requirement is that all CFT-negative animals from the last CFT must also be negative in a follow-up “in parallel” IFN-γ test. CFT cut-off is any visible or palpable swelling
	Direct slaughter of intradermal test-positive animals or on approval, ancillary blood testing using the standard PPD IFN-γ test in cases of known non specificity
	Pre-movement testing, CFT followed by parallel IFN-γ test (cut-off of Bovine PPD OD minus Avian PPD OD ≥0.07), white movement control tags applied and official permit to move required

CFT=caudal fold test; IFN-γ=interferon gamma; OD=optical density; PPD=purified protein derivative

Table 3. Results of culturing samples following identification of macroscopic lesions at slaughter that were typical or suspicious of tuberculosis in cattle and deer from 2003 to 2009 in New Zealand.

	Cattle	Farmed deer	Feral deer ^a	Total
Mycobacterium bovis	1,695	412	23	2,130
Mycobacterium pinnipedii	3	0	0	3
Mycobacterium avium complex ^b	28	405	1	434
Mycobacterium avium subsp. paratuberculosis	2	1,677	NA ^c	1,679
Other mycobacteria	2	19	7	28
Rhodococcus equi	294	81	0	375
No mycobacteria or R. equi isolated	2,452	1,689	2,985	7,126
Total	4,476	4,283	3,016	11,775

^a Culture results of feral deer mostly include non-lesioned lymph nodes collected as part of surveillance operations

^b Excluding M. avium subsp. paratuberculosis

^c No mycobactin-supplemented media was included for culturing samples from feral deer