Theoretical and Experimental Approaches to Estimate the Usefulness of Pooled Serum Samples for the Diagnosis of Postweaning Multisystemic Wasting Syndrome

Cortey, Martı́; Napp, Sebastián; Alba, Anna; Pileri, Emanuela; Grau‐Roma, Llorenç; Sibila, Marina; Segalés, Joaquím

doi:10.1177/104063871102300206

Cited by 11 publications

(9 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7 The majority of the reported pooling procedures have involved dichotomized test results demonstrating the presence or absence of a biological substance or organism. Quantitative investigations of pooled specimens have been evaluated for herd-level diagnosis of postweaning multisystemic wasting syndrome in pigs, 2 although pooling has primarily been used in relation to microarray experiments. Quantitative investigations using microarray technology have biological averaging as a basic assumption in relation to pooling.…”

Section: Introductionmentioning

confidence: 99%

Pooling of porcine fecal samples for quantification of Lawsonia intracellularis by real-time polymerase chain reaction

et al. 2014

View full text Add to dashboard Cite

Abstract. Procedures in which biological specimens are mixed and tested as 1 sample (pooling) have been applied for various biological specimens and laboratory examinations. The objective of the current study was to investigate agreement between laboratory testing of fecal pools and theoretical values obtained by averaging test results from individual fecal samples in relation to a quantitative polymerase chain reaction (qPCR) test for Lawsonia intracellularis. Ten diarrheic and 10 normal fecal samples were submitted from each of 43 Danish swine herds (n = 860 fecal samples). Pools (n = 43), each containing 20 individual fecal samples from the same herd, were prepared in the laboratory by pooling 10% fecal phosphate buffered saline solutions. All pools and individual fecal samples were subjected to qPCR testing for L. intracellularis. The theoretical number of L. intracellularis in the pools was calculated as the mean number of bacteria from the 20 individual fecal samples contributing to each pool. Agreement between the laboratory testing of pools and theoretical calculations based on individual sample results was evaluated. Pooling resulted in fewer L. intracellularis-positive herds (41.9%) compared with testing 20 fecal samples (53.5%). Agreement between the laboratory and the theoretical pools for dichotomized test results was 100% (95% confidence interval: 91.8-100%). For the quantitative test results, Lin concordance correlation coefficient was 0.997. The mean difference between the laboratory testing and the theoretical values was not different from zero (mean difference = 0.039 log 10 bacteria/g feces; P = 0.26).

show abstract

Section: Introductionmentioning

confidence: 99%

Pooling of porcine fecal samples for quantification of Lawsonia intracellularis by real-time polymerase chain reaction

et al. 2014

View full text Add to dashboard Cite

show abstract

“…As with the higher proportion of positives, a higher viral load in oral fluid was expected because far more pigs were sampled with oral fluid. Earlier studies demonstrating a high variation of viral loads in serum between individual pigs within a group support this [ 18 , 44 ]: In 10 animals in each of 5 different PMWS-negative farms, ranges between <4 (detection limit) and 8.7 log(10) PCV2 copies per ml serum within the same farm and age group were found [ 18 ]. And in a vaccination trial, a mean level of 6.1 log(10) and a standard deviation of 1.7 log(10) PCV2 copies per ml serum in 8 PCV2-positive control pigs were reported [ 44 ].…”

Section: Discussionmentioning

confidence: 76%

“…Serum samples and nasal swabs have been suggested to be more suitable for evaluating PMWS status for a group of pigs than for individuals [ 9 ] and pooled samples could be a further development of this. However, it was later concluded that qPCR testing of pooled serum samples was not sufficiently reliable for diagnosis of PMWS at herd level but might be useful for determination of viral loads [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Comparison of serum pools and oral fluid samples for detection of porcine circovirus type 2 by quantitative real-time PCR in finisher pigs

Nielsen¹,

Nielsen

Haugegaard³

et al. 2018

Porc Health Manag

View full text Add to dashboard Cite

BackgroundPorcine circovirus type 2 (PCV2) diagnostics in live pigs often involves pooled serum and/or oral fluid samples for group-level determination of viral load by quantitative real-time polymerase chain reaction (qPCR). The purpose of the study was to compare the PCV2 viral load determined by qPCR of paired samples at the pen level of pools of sera (SP) from 4 to 5 pigs and the collective oral fluid (OF) from around 30 pigs corresponding to one rope put in the same pen. Pigs in pens of 2 finishing herds were sampled by cross-sectional (Herd 1) and cross-sectional with follow-up (Herd 2) study designs. In Herd 1, 50 sample pairs consisting of SP from 4 to 5 pigs and OF from around 23 pigs were collected. In Herd 2, 65 sample pairs consisting of 4 (SP) and around 30 (OF) pigs were collected 4 times at 3-week intervals.ResultsA higher proportion of PCV2-positive pens (86% vs. 80% and 100% vs. 91%) and higher viral loads (mean difference: 2.10 and 1.83 log(10) PCV2 copies per ml) were found in OF versus SP in both herds. The OF cut-off value corresponding to a positive SP (>3 log(10) PCV2 copies per ml) was estimated to 6.5 and 7.36 log(10) PCV2 copies per ml for Herds 1 and 2, respectively. Significant correlations between SP and OF results were found in Herd 1 (rho = 0.69) and the first sampling in Herd 2 (rho = 0.39), but not for the subsequent consecutive 3 samplings in Herd 2.ConclusionsThe proportion and viral loads of PCV2 positive pens were higher in collective OF (including up to 30 pigs) compared to SP (including 4–5 pigs) of the same pens. Also, OF seemed to detect the PCV2 infection earlier with OF values just below 6.5 (Herd 1) and 7.36 (Herd 2) log(10) being associated with a negative SP for the same pen. Nevertheless, a statistically significant correlation between SP and OF could not be found for all sampling time points, probably due to a high within-pen variation in individual pig viral load becoming very evident in SP of only four or five pigs. Consequently, the results imply that OF is well suited for detecting presence of PCV2 but less so for determining the specific viral load of pigs in a pen.

show abstract

“…The effect of pooling has been validated on field samples and shown to have limited effect on the sensitivity and specificity of the test (unpublished results), as has been shown by others [13]. The detection limit of the PCR assay used was 3 log 10 PCV2 copies/mL serum [12].…”

Section: Methodsmentioning

confidence: 94%

A two-year follow-up study of the PCV2 status of a Danish pig herd that was initially assumed to be PCV2-free

2015

View full text Add to dashboard Cite

BackgroundA longitudinal study was carried out to investigate whether a herd that had previously tested negative for porcine circovirus type 2 (PCV2) by polymerase chain reaction (PCR) was free of PCV2 or whether the negative profiles indicate that the level of PCV2 varies over time.ResultsIn eight Danish herds that had initially tested negative for PCV2 by quantitative polymerase chain reaction (PCR), additional sampling was performed. Only one of the herds was still PCV2-negative in the additional sampling and was included in the study.The herd was a finishing herd, subclinically infected with PCV2, but vaccinated against PCV2 to improve performance. The herd was monitored by taking blood samples every seventh week over a period of two years and was not found to be continuously negative for PCV2 by PCR. The first time PCV2 was detected by PCR, in May 2010, PCV2 vaccination had been withdrawn from the herd, and at the same time the herd was infected with porcine reproductive and respiratory syndrome virus (PRRS). The PCV2-negative status, measured by PCR, was obtained in the first sampling after the PCV2 vaccination had been reintroduced. When PCV2 vaccination was withdrawn again in September 2011, the herd tested positive for PCV2 by PCR, and this time it continued to be PCV2-positive, even though PCV2 vaccination had been reintroduced.ConclusionA Danish finishing herd that appeared to be PCV2-free from the start of a period of two years was not free of PCV2 during the entire period.

show abstract

Theoretical and Experimental Approaches to Estimate the Usefulness of Pooled Serum Samples for the Diagnosis of Postweaning Multisystemic Wasting Syndrome

Cited by 11 publications

References 34 publications

Pooling of porcine fecal samples for quantification of Lawsonia intracellularis by real-time polymerase chain reaction

Pooling of porcine fecal samples for quantification of Lawsonia intracellularis by real-time polymerase chain reaction

Comparison of serum pools and oral fluid samples for detection of porcine circovirus type 2 by quantitative real-time PCR in finisher pigs

A two-year follow-up study of the PCV2 status of a Danish pig herd that was initially assumed to be PCV2-free

Contact Info

Product

Resources

About