Efficacy of a killed vaccine for the control of paratuberculosis in Australian sheep flocks

Reddacliff, L.A.; Eppleston, J; Windsor, Peter; Whittington, Richard J.; Jones, Stephen L.

doi:10.1016/j.vetmic.2005.12.021

Cited by 131 publications

(155 citation statements)

References 15 publications

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“…It is based on a convenient sample of flocks as it was considered sensible to utilise commercial flocks that had been vaccinating for five or more years. A randomised controlled clinical trial -as conducted in the initial evaluation of the vaccine in Australia when mortalities were high (Reddacliff et al, 2006) -would have been an ideal for evaluating effectiveness of a vaccine, but it is difficult to implement in current real-life on-farm situations. It would be almost impossible to ask farmers to agree on not vaccinating sheep for 4-5 years for OJD, particularly, if they have high disease prevalence.…”

Section: Discussionmentioning

confidence: 99%

“…Thirdly, different tests or combination of tests were used pre-and postvaccination and the tests used different reference units (individual animal for AGID and a pool of faeces for PFC). The differences in use of diagnostic tests partly reflected the emergence of PFC as a test of choice in Australia as it replaced the previously preferred test, the AGID (Reddacliff et al, 2006). This necessitated the use of Bayesian approach which accounted for these uncertainties and allowed us to calculate and objectively compare true prevalence after adjusting for these differences in diagnostic tests.…”

Section: Discussionmentioning

confidence: 99%

“…Effectiveness of the vaccine is likely to be better in flocks with higher prevalence, as found previously. For example, a study conducted in three heavily infected flocks found that vaccination delayed the onset of faecal shedding of MAP by 12 months, and reduced the prevalence of shedders by 90% compared to unvaccinated lambs (Reddacliff et al, 2006). Another investigation conducted on seven heavily infected farms demonstrated persistence of shedding but with a significant decline in the mean flock prevalence (Eppleston et al, 2005).…”

Section: Discussionmentioning

confidence: 99%

“…While it is considered to be very effective in controlling mortalities, several studies in low numbers of flocks have shown that MAP shedding continues to occur in vaccinated sheep (Eppleston et al, 2005;Reddacliff et al, 2006;Windsor, 2006). The persistence of shedding for an extended period following the onset of a vaccination programme presents a risk for spread to other flocks.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of pre- and post-vaccination ovine Johne's disease prevalence using a Bayesian approach

Dhand

Johnson

Eppleston

et al. 2013

Preventive Veterinary Medicine

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This study was conducted to evaluate the effectiveness of Gudair TM vaccine in decreasing the prevalence of shedding of Mycobacterium avium subsp. paratuberculosis (MAP) in flocks of varying initial prevalence. Thirty seven self-replacing Merino flocks from New South Wales and Victoria (Australia) that had been vaccinating lambs with Gudair TM for at least five years were enrolled in the study. These flocks had been tested prior to or at commencement of vaccination using pooled faecal culture, agar gel immunodiffusion or both tests. These prevaccination test results were used to estimate pre-vaccination prevalence. Post-vaccination prevalence was estimated from culture of usually 7 pools of 50 sheep collected from the enrolled flocks in [2008][2009], approximately five or more years after commencement of vaccination.A Bayesian model was developed to estimate and compare the pre-and postvaccination prevalences for the enrolled flocks. Apparent pre-and post-vaccination prevalences for flocks were modelled as functions of the true pre-and post-vaccination prevalences, respectively, and the sensitivities and specificities of the respective diagnostic tests. Logit-normal models were specified on pre-and post-vaccination true prevalences and were then used to make inferences about the median and 90 th percentile of the prevalence 2 distributions and their differences. Priors were mostly specified based on published literature or analysis of abattoir surveillance data for this population of flocks.The analysis found a significant decline in ovine Johne's disease prevalence from a pre-vaccination median prevalence of 2.72% [95% probability interval (PI): 1.40; 6.86%] to a post-vaccination median prevalence of 0.72% (0.39; 1.27%). However 30 of the 37 flocks still contained sheep that were shedding MAP in their faeces. The results suggest that vaccination with Gudair™ is usually effective in reducing the prevalence of faecal shedding but the response to vaccination is variable among flocks. This approach could be implemented in similar situations to compare prevalences where information from multiple diagnostic tests with varied sensitivities and specificities is available.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Comparison of pre- and post-vaccination ovine Johne's disease prevalence using a Bayesian approach

Dhand

Johnson

Eppleston

et al. 2013

Preventive Veterinary Medicine

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“…Prophylactic vaccination has been employed as a control measure, even though not completely effective in preventing disease (Cocito et al, 1994). Vaccination with heat inactivated whole cell based vaccines is widely in practice in Australia (Gudair TM ) and USA (Mycopar TM ) (Reddacliff et al, 2006;Koets et al, 2006). The protective efficacy of these vaccines has been tested in sheep and cattle (Munoz et al, 2005;Reddacliff et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Quantification of Mycobacterium avium subsp. paratuberculosis from the tissues of challenged mice using SYBR Green real time PCR assay for the assessment of vaccine efficacy

Chaitanya

Reddy

Raj

et al. 2018

IJAR

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A SYBR Green real time PCR assay amplifying F57 gene of Mycobacterium avium subsp. paratuberculosis (MAP) was developed to evaluate the protective efficacy of the inactivated vaccine to prevent the colonization of MAP in the tissues of BALB/c mice challenge model. Bacterial burden in the liver, spleen and intestine of vaccinated and sham immunized control mice, after intra peritoneal challenge with MAP were quantified by real time PCR assay. A 195 bp fragment of MAP F57 sequence was cloned into TA cloning vector and the resultant recombinant plasmid was used to generate a series of quantification standards with copy number ranging from 10 9 to 1 copy. This absolute quantification technique is rapid and able to detect as few as 10 MAP organisms per gram of tissue and the assay has the efficiency of 0.982.

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Seroprevalence of anti‐Mycobacterium avium subsp. paratuberculosis antibodies in female sheep in Tunisia

Khbou¹,

Romdhane²,

Sassi³

et al. 2020

Veterinary Medicine & Sci

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Paratuberculosis (Ptb) is a widespread chronic infection caused by Mycobacterium avium subsp. paratuberculosis ( Map ) that affects both domestic and wild ruminants. Most of the studies focused on cattle while, the prevalence of Ptb in sheep in different regions of the world is not well investigated. This study aimed to address this gap of knowledge by screening adult female sheep for paratuberculosis antibodies in different geographical regions of Tunisia. A total number of 338 female sheep from 15 small to middle‐sized, extensively managed sheep farms in six regions across Tunisia were sampled. Animals were clinically examined before blood sampling. Sera were tested for the presence of anti‐ Mycobacterium avium subsp. paratuberculosis antibodies using a commercial ELISA kit. Six farms out of 15 comprised at least one seropositive animal and 11 female sheep out of 338 tested animals (3.25%; 95% CI = [1.83–5.73]) were seropositive to M. avium subsp. paratuberculosis . The seroprevalence was significantly lower in 5‐year‐old females ( p = .04) and animals that do not graze ( p = .02). Due to its huge economic and social impacts, paratuberculosis represents a health problem in Tunisia and several other countries Further investigations are needed to rank sheep Ptb in Tunisia among other diseases and to assess the main risk factors using a larger nation‐wide survey.

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Efficacy of a killed vaccine for the control of paratuberculosis in Australian sheep flocks

Cited by 131 publications

References 15 publications

Comparison of pre- and post-vaccination ovine Johne's disease prevalence using a Bayesian approach

Comparison of pre- and post-vaccination ovine Johne's disease prevalence using a Bayesian approach

Quantification of Mycobacterium avium subsp. paratuberculosis from the tissues of challenged mice using SYBR Green real time PCR assay for the assessment of vaccine efficacy

Seroprevalence of anti‐Mycobacterium avium subsp. paratuberculosis antibodies in female sheep in Tunisia

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