Age-structured dynamic, stochastic and mechanistic simulation model of Salmonella Dublin infection within dairy herds

Nielsen, Liza Rosenbaum; Kudahl, Anne Braad; Østergaard, Søren Dinesen

doi:10.1016/j.prevetmed.2012.02.005

Cited by 16 publications

(10 citation statements)

References 43 publications

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“…Dublin carriage detection based on repeated antibody measurements should be regarded as a very uncertain method for use as a control element in persistently infected dairy herds. The age associations indicated a more likely benefit of directing the focus towards methods to prevent the spread of bacteria between calves and young stock, including consistent sectioning and careful cleaning of the environment and housing equipment on a regular basis as suggested in previous studies [6, 31, 32].…”

Section: Discussionmentioning

confidence: 77%

SalmonellaDublin faecal excretion probabilities in cattle with different temporal antibody profiles in 14 endemically infected dairy herds

Nielsen

2012

Epidemiol. Infect.

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This longitudinal field study investigated the hypothesis that persistently high antibody levels indicate a high risk of Salmonella Dublin shedding in animals in 14 endemically infected dairy herds. A hierarchical multivariable logistic regression was used to analyse 6614 paired faecal cultures and four types of temporal antibody profiles from cattle aged ≥180 days. Age and repeated measurements on animals nested within herds were taken into account. Overall, the prevalence of faecal shedders was low (0·3% and 2·8% in the lowest and highest risk groups, respectively). An important predictor of faecal shedding was young age. There was a significant, but modest increase in risk in cattle with persistently high or recently increased antibody levels, but no difference between these two groups. Contrary to previous recommendations, the detection of carriers by the use of repeated antibody testing is not likely to be a plausible control option in most Salmonella Dublin-infected dairy herds.

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Section: Discussionmentioning

confidence: 77%

SalmonellaDublin faecal excretion probabilities in cattle with different temporal antibody profiles in 14 endemically infected dairy herds

Nielsen

2012

Epidemiol. Infect.

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“…The lack of any evidence for a difference between detection results from the immature and adult cattle may be due to younger animals being kept in smaller groups and on straw, making sampling more difficult than for adult cattle groups despite a greater likelihood of infection and high-level shedding in younger animals [23]. An earlier study [9] reported that pooling of individually collected cattle faeces produced reliable results when there were ≤20 animals per group, but in naturally pooled faeces from a large number of animals the chance of inclusion of material from a high-level shedder in the pool is increased [24].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the sensitivity of faecal sampling for detection of monophasicSalmonellaTyphimurium and otherSalmonellain cattle and pigs

et al. 2014

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There has been a rapid rise in the prevalence of cases of monophasic Salmonella Typhimurium (mST) in both humans and farm animals, and it has been found in pigs, cattle and poultry. It is therefore vital to have a good understanding of how to efficiently detect infected farms. The objective of this project was to determine sample type sensitivity in the detection of Salmonella to detect infected groups of animals on both pig (breeder, grower and finisher sites) and cattle (beef and dairy) farms, using data collected from a study investigating farms that were positive for mST, and to explore any variation between different age groups and management practices. A Bayesian approach in the absence of a gold standard was adopted to analyse the individual and pooled faecal sample data collected from each epidemiological group on each of the farms. The sensitivity of pooled sampling depended on the prevalence of infection in the group being sampled, with a higher prevalence leading to higher sensitivity. Pooled sampling was found to be more efficient at detecting positive groups of animals than individual sampling, with the probability of a random sample from a group of animals with 5% prevalence testing positive being equal to 15·5% for immature pigs (3·6% for an individual faecal sample, taking into account the sensitivity and infection prevalence), 7·1% for adult pigs (1·2% for individual sampling), 30% for outdoor cattle (2% for individual sampling) and 34% for indoor cattle (1% for individual sampling). The mean prevalence of each epidemiological group was higher in outdoor farms than indoor for both pigs and cattle (mean within-farm prevalence of 29·4% and 38·7% for outdoor pigs and cattle, respectively, compared to 19·8% and 22·1% for indoor pigs and cattle).

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“…Dublin is a very dynamic infection within cattle herds. Moreover, in some barn sections the cattle populations are also very dynamic with a continuous or fluctuating number of new animals with varying susceptibility to the infection being introduced to the age groups over time [7, 25].…”

Section: Discussionmentioning

confidence: 99%

“…In order to design effective control programmes, good estimates of within-herd prevalence of infection are required [4,5]. Furthermore, within-herd prevalence estimates are needed for development and validation of theoretical models of S. Dublin infection dynamics [6][7][8]. There are, however, very few published studies available that provide good insight into within-herd prevalence and dynamics of S. Dublin, in particular for persistently infected cattle herds.…”

Section: Introductionmentioning

confidence: 99%

Within-herd prevalence ofSalmonellaDublin in endemically infected dairy herds

Nielsen

2013

Epidemiol. Infect.

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In this study within-herd prevalence of Salmonella Dublin was investigated in three age groups (calves, young stock, adult cows) during five herd visits at 3-month intervals of 14 endemically infected dairy herds. A total of 10162 paired faecal cultures and antibody measurements were used to calculate the age and temporal dynamics of seroprevalence and prevalence of positive faecal cultures. Faecal culture-positive prevalence was generally low. It was highest (5.4%) in calves during December to February. Seroprevalence varied from 0% to 70% between herds, but was generally more stable in young stock and adult cows than in calves. Hierarchical mixed-model results showed that seroprevalence was associated with the bacteriological status in calves and cows, but not in young stock. These results can be used to develop and validate theoretical infection dynamics models and to design effective control programmes for Salmonella Dublin in dairy herds.

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Age-structured dynamic, stochastic and mechanistic simulation model of Salmonella Dublin infection within dairy herds

Cited by 16 publications

References 43 publications

SalmonellaDublin faecal excretion probabilities in cattle with different temporal antibody profiles in 14 endemically infected dairy herds

SalmonellaDublin faecal excretion probabilities in cattle with different temporal antibody profiles in 14 endemically infected dairy herds

Evaluation of the sensitivity of faecal sampling for detection of monophasicSalmonellaTyphimurium and otherSalmonellain cattle and pigs

Within-herd prevalence ofSalmonellaDublin in endemically infected dairy herds

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