TY - JOUR
T1 - Is vaccination a viable method to control Johne's disease caused by Mycobacterium avium subsp. paratuberculosis?
T2 - Data from 12 million ovine vaccinations and 7.6 million carcass examinations in New South Wales, Australia from 1999-2009
AU - Links, Ian J.
AU - Denholm, Laurence J.
AU - Evers, Marilyn
AU - Kingham, Lloyd J.
AU - Greenstein, Robert J.
N1 - Publisher Copyright:
© 2021 Links et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
PY - 2021/6/14
Y1 - 2021/6/14
N2 - BackgroundMycobacterium avium subsp. paratuberculosis
(MAP) causes Johne’s disease (or paratuberculosis), a chronic wasting
disease of ruminants and other animals resulting from granulomatous
enteritis. There are increasing concerns that MAP is zoonotic. The
prevalence of Johne’s disease is increasing worldwide. In an attempt to
control an epidemic of ovine Johne’s disease (OJD) in New South Wales
(NSW), a government/industry sponsored voluntary vaccination/on-farm
management program commenced in 2000. We report herein an observational
study of changes in disease prevalence as vaccination progressed, based
on abattoir surveillance data for OJD from 1999 to 2009. We also discuss
the epidemiological, policy, regulatory, research, economic and
sociological elements that contributed to the development of a mature
control program, whose aim was to halt the epidemic spread of OJD in a
naïve sheep population.
Methods
NSW
was divided into areas of “High” (HPA), “Medium” (MPA) and “Low” (LPA)
OJD prevalence. A killed whole cell vaccine (Gudair®) was administered
to sheep from 2000 to 2009. Trained examiners evaluated the viscera of
adult sheep carcasses at slaughter for gross evidence of OJD. MAP
infection was confirmed by histopathology.
Principal findings
From
2000–2009, 12 million vaccine doses were administered in NSW (91%; 10.9
million in the HPA). Many of the vaccinated flocks were suffering >
5% annual mortality in adult sheep, with some individual flocks with
10–15% losses attributable to OJD. A total of 7.6 million carcasses were
examined (38%; 2.9 million from the HPA). Overall, 16% of slaughter
consignments (sheep consigned to the abattoir from a single vendor) were
positive for OJD, of which 94% were from the HPA. In the HPA, the
percentage of animals with lesions attributable to OJD at slaughter fell
progressively from 2.4% (10,406/432,860) at commencement of vaccination
in 2000 to 0.8% (1,573/189,564) by 2009. Herd immunity from vaccination
in the HPA was estimated at 70% by 2009, the target commonly espoused
for an effective control program based on vaccination. This coincided
with a progressive decrease in reports of clinical disease and
mortalities in vaccinated flocks.
Significance
We
show a decrease in the prevalence of lesions attributable to OJD in NSW
concomitant with initiation of voluntary vaccination, on-farm
management plans, abattoir monitoring and feedback of animal prevalence
data to sheep producers. We conclude that a target of ≤ 1% regional
prevalence of OJD affected sheep at slaughter is achievable using these
interventions.
AB - BackgroundMycobacterium avium subsp. paratuberculosis
(MAP) causes Johne’s disease (or paratuberculosis), a chronic wasting
disease of ruminants and other animals resulting from granulomatous
enteritis. There are increasing concerns that MAP is zoonotic. The
prevalence of Johne’s disease is increasing worldwide. In an attempt to
control an epidemic of ovine Johne’s disease (OJD) in New South Wales
(NSW), a government/industry sponsored voluntary vaccination/on-farm
management program commenced in 2000. We report herein an observational
study of changes in disease prevalence as vaccination progressed, based
on abattoir surveillance data for OJD from 1999 to 2009. We also discuss
the epidemiological, policy, regulatory, research, economic and
sociological elements that contributed to the development of a mature
control program, whose aim was to halt the epidemic spread of OJD in a
naïve sheep population.
Methods
NSW
was divided into areas of “High” (HPA), “Medium” (MPA) and “Low” (LPA)
OJD prevalence. A killed whole cell vaccine (Gudair®) was administered
to sheep from 2000 to 2009. Trained examiners evaluated the viscera of
adult sheep carcasses at slaughter for gross evidence of OJD. MAP
infection was confirmed by histopathology.
Principal findings
From
2000–2009, 12 million vaccine doses were administered in NSW (91%; 10.9
million in the HPA). Many of the vaccinated flocks were suffering >
5% annual mortality in adult sheep, with some individual flocks with
10–15% losses attributable to OJD. A total of 7.6 million carcasses were
examined (38%; 2.9 million from the HPA). Overall, 16% of slaughter
consignments (sheep consigned to the abattoir from a single vendor) were
positive for OJD, of which 94% were from the HPA. In the HPA, the
percentage of animals with lesions attributable to OJD at slaughter fell
progressively from 2.4% (10,406/432,860) at commencement of vaccination
in 2000 to 0.8% (1,573/189,564) by 2009. Herd immunity from vaccination
in the HPA was estimated at 70% by 2009, the target commonly espoused
for an effective control program based on vaccination. This coincided
with a progressive decrease in reports of clinical disease and
mortalities in vaccinated flocks.
Significance
We
show a decrease in the prevalence of lesions attributable to OJD in NSW
concomitant with initiation of voluntary vaccination, on-farm
management plans, abattoir monitoring and feedback of animal prevalence
data to sheep producers. We conclude that a target of ≤ 1% regional
prevalence of OJD affected sheep at slaughter is achievable using these
interventions.
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U2 - 10.1371/journal.pone.0246411
DO - 10.1371/journal.pone.0246411
M3 - Review article
C2 - 34125838
AN - SCOPUS:85108011675
SN - 1932-6203
VL - 16
SP - 1
EP - 38
JO - PLoS One
JF - PLoS One
IS - 6
M1 - e0246411
ER -