ANNUAL REPORT 2014/2015

OSPRI | DISEASE CONTROL 2014/2015
DEER
Infected deer herds
At 30 June 2015, there were two
infected deer herds (0.08% of the
total farmed deer herd population).
Both herds were located in South
Island VRAs.
Figure 4 shows that since June 2003,
there has been a relatively steep
decline in the number of infected
herds and then a levelling off at very
low numbers since June 2011.
The reduction since 2003/2004 is
largely due to maintaining low possum
densities over large areas of New
Zealand. It also reflects a period when
there was a large reduction in the
number of deer being farmed due to
low financial returns for venison and
velvet. Ferret trapping in TB risk areas,
and testing policy changes aimed at
clearing infected herds more quickly,
also contributed to the decrease
early in this period, particularly in the
Canterbury and Otago VRAs.
It is expected that the number of
infected deer herds will continue to
remain low.
Deer testing and reactors
Deer testing data is summarised
in Table 5, which compares the
number of TB tests performed and
the number of reactors with tests
in 2013/2014 and 2014/2015. In
the year to 30 June 2015, 252,551
primary mid-cervical intradermal
tuberculin tests (skin tests) were
performed on deer compared with
252,682 in 2013/2014.
During the year, 1240 deer tested
positive to the mid-cervical skin test
and 207 of these were slaughtered
without further testing. The remaining
1033 deer were administered serial
ancillary tests including:
• comparative cervical skin tests on
110 deer, with no positive animals,
and
• ETB or Modified ETB (IgG1
ELISA) tests on 923 deer, of
which 27 (3%) tested positive
and were declared TB reactors.
On slaughter, two (7%) of the TB
reactors were found to have TB
lesions or M. bovis. confirmed.
No ancillary parallel ELISA tests were
performed on deer in 2014/2015.
A crude mid-cervical test specificity
of 99.9% can be derived from this
data (deer positive to the primary
test as a percentage of deer tested,
assuming all test positives were
not infected).
Figure 5 shows the trend in deer
reactors from 2002/2003 to 2014/
2015 by TB risk status area. Future
reactor deer numbers are expected
to fluctuate between 150 and 400.
Tuberculous deer
The number of tuberculous deer
includes the total number of deer
(including reactors and deer
found during routine slaughter)
with visible TB-like lesions – or
otherwise identified as infected
following PCR assay or culture of
M. bovis from tissues.
During 2014/2015, there were three
reactors with visible TB lesions and
one animal found with TB lesions
during routine slaughter. Figure
6 shows the trend in the number
of tuberculous deer between
2002/2003 and 2014/2015.
Table 5: Deer TB testing results for 2013/2014 and 2014/2015
Deer testing 2013/2014 2014/2015
Primary tuberculin tests on deer 252,682 252,551
Deer positive to primary mid-cervical test 1925 1240
Primary test-positive deer slaughtered 165 207
Primary test-positive deer ancillary serial tested 1760 1033
Ancillary serial test-positive deer 66 27
Ancillary parallel test-positive deer 0 0
Total deer reactors slaughtered
231
(9/10,000)
234
(9/10,000)
56