Diarrhoea in neonatal piglets: a case control study on microbiological findings.

BACKGROUND: Many factors can influence the occurrence of neonatal diarrhoea in piglets. Currently, well-known pathogens such as enterotoxigenic Escherichia coli and Clostridium perfringens type C appear to play a minor role in development of disease. Other infectious pathogens may be involved. In this study, we aimed to investigate the presence of selected infectious pathogens in neonatal piglets with clinical and pathological signs of enteric disease. The association between rotavirus A, Enterococcus hirae, Clostridium difficile and Clostridium perfringens type A/C and diarrhoea was investigated in a case control study on piglet level. The possible role of E. coli virulence factors was investigated in a multistep-procedure using herd-pools of E.coli isolates to screen for their presence. RESULTS: Rotavirus A was detected more often in cases (25%) than in controls (6%) (P < 0.001). The detection rate of Enterococcus hirae, Clostridium difficile and C. perfringens type A positive for beta2 genes was the same in the two groups of piglets. C. perfringens type C was not detected in the study. Investigations on E. coli virulence factors showed a high prevalence of EAST1 toxin genes (55% of tested case piglets were positive) and AIDA-1 adhesin genes (63% of toxin positive case piglets were positive) in case piglets. CONCLUSIONS: Detection of rotavirus A was statistically significantly associated with neonatal piglet diarrhoea.An aetiologic role of E. coli carrying virulence factors EAST1 and AIDA-1 needs further investigation as the study points out these two factors as possible causative factors in neonatal diarrhoea.Detection of E.hirae, C.difficile and C. perfringens type A carrying beta 2 genes was not associated with neonatal piglet diarrhoea. However, the study suggested that massive overgrowth by E. hirae could be part of the pathogenesis in some cases of neonatal diarrhoea.

A cross-sectional study of oral antibacterial treatment patterns in relation to specific diarrhoeal pathogens in weaner pigs.

According to international guidelines, the use of antibacterials should be evidence based and prudent. This register-based, cross-sectional study investigates the potential effect of laboratory findings on the patterns of antibacterial oral (batch) medication of weaner pigs, and the level of compliance with national guidelines for antibacterial use. The study population includes 1,736 weaner herds (≈65% of all Danish weaner pigs) that were subject to laboratory analysis from the National Veterinary Institute on Brachyspira pilosicoli, Lawsonia intracellularis, and E.coli (F4 and F18) in 2014. Antibacterial prescription data were obtained from the national database, VetStat. These showed that antibacterial prescriptions for use in weaner pigs was 8.6% lower in spring 2015 compared to spring 2014. The antibacterial use per pig tended (p=0.08) to decrease more in herds with negative laboratory results compared to herds with a moderate or massive occurrence of either of the pathogens. Irrespective of the laboratory findings on diarrhoeal pathogens, tetracyclines were the most frequently used antibacterials by a substantial margin, both 3 months prior to and 2-5 months after laboratory analysis. According to the national guidelines, tetracyclines are the second or third-choice antibacterial for treatment of diarrhoeal pathogens, due to resistance and co-resistance patterns. Compliance with the guidelines increased in 14% of the herds, mostly following identification of B. pilosicoli within the herd. Between 10% and 20% of the herds did not use batch treatment, despite the presence of moderate-massive amounts of the pathogens.

Clinical utility and performance of sock sampling in weaner pig diarrhoea.

Low pathogen diarrhoea is a group-level diagnosis, characterised by non-haemorrhagic diarrhoea. In the current study, the apparent prevalence of low pathogen diarrhoea outbreaks in Danish herds was investigated along with the clinical utility of a laboratory examination for intestinal disease, agreement between three consecutive herd examinations from the same herd and agreement between quantitative PCR results from pooled faecal samples and sock samples. Twenty-four veterinarians submitted faecal and sock samples for quantitative PCR testing from outbreaks of diarrhoea in nursery pigs (n=38 herds) where the farmer or veterinarian had decided that antimicrobial treatment was necessary. The veterinarians were asked to fill in a questionnaire and participate in telephone interviews. The apparent prevalence of low pathogen diarrhoea was 0.18 (95% CL: 0.08-0.34). Agreement between the veterinarians' clinical aetiological diagnosis and the pooled faecal sample was 0.18 (95% CL: 0.08-0.34), and Cohen's Kappa was 0.03 (95% CL: -0.08 to 0.14). Antibiotic treatment or prevention strategies were changed in 0.63 (95% CL: 0.46-0.78) of the herds, and the veterinarians indicated that, for 0.32 (95% CL: 0.18-0.50) of the herds, changes were related to the diagnostic results from the laboratory examination performed in the study. In 0.16 (95% CL: 0.05-0.36) of the herds, the same infections were demonstrated at all three consecutive examinations. No herds had three consecutive diarrhoea outbreaks classified as low pathogen diarrhoea. For the quantitative results (log10 of the summed amounts of Lawsonia intracellularis, Brachyspira pilosicoli, Escherichia coli F4 and F18) agreement between pooled faecal samples and sock samples was evaluated. Lin's concordance correlation coefficient was 0.69 (95% CL: 0.48-0.82), and the mean difference between the two types of samples was -0.38 log10 bacteria/g faeces (SD=1.59log10 bacteria/g faeces; 95% CI: -0.90 to 0.14log10 bacteria/g faeces). Agreement for the dichotomised results was 0.89 (95% CI: 0.75-0.97) when test results were classified as low pathogen diarrhoea or not, and Cohen's Kappa was 0.61 (95% CI: 0.26-0.95). In relation to detection of the individual infections, agreement was 0.63 (95% CI: 0.46-0.78), and Cohen's Kappa was 0.53 (95% CI: 0.34-0.71). In conclusion, low pathogen diarrhoea is a common finding amongst diarrhoea outbreaks that are subjected to antibiotic batch treatment in Danish nursery pigs. Sock samples seem to offer a reliable diagnostic method with impact on clinical decisions for treatment and prevention. However, both the diarrhoea type and the aetiology change with time in the majority of herds, indicating a potential need for frequent diagnostic examinations.

Herd diagnosis of low pathogen diarrhoea in growing pigs - a pilot study.

BACKGROUND: The major indication for antibiotic use in Danish pigs is treatment of intestinal diseases post weaning. Clinical decisions on antibiotic batch medication are often based on inspection of diarrhoeic pools on the pen floor. In some of these treated diarrhoea outbreaks, intestinal pathogens can only be demonstrated in a small number of pigs within the treated group (low pathogen diarrhoea). Termination of antibiotic batch medication in herds suffering from such diarrhoea could potentially reduce the consumption of antibiotics in the pig industry. The objective of the present pilot study was to suggest criteria for herd diagnosis of low pathogen diarrhoea in growing pigs. Data previously collected from 20 Danish herds were used to create a case series of clinical diarrhoea outbreaks normally subjected to antibiotic treatment. In the present study, these diarrhoea outbreaks were classified as low pathogen (<15% of the pigs having bacterial intestinal disease) (n =5 outbreaks) or high pathogen (≥15% of the pigs having bacterial intestinal disease) (n =15 outbreaks). Based on the case series, different diagnostic procedures were explored, and criteria for herd diagnosis of low pathogen diarrhoea were suggested. The effect of sampling variation was explored by simulation. RESULTS: The diagnostic procedure with the highest combined herd-level sensitivity and specificity was qPCR testing of a pooled sample containing 20 randomly selected faecal samples. The criteria for a positive test result (high pathogen diarrhoea outbreak) were an average of 1.5 diarrhoeic faecal pools on the floor of each pen in the room under investigation and a pathogenic bacterial load ≥35,000 per gram in the faecal pool tested by qPCR. The bacterial load was the sum of Lawsonia intracellularis, Brachyspira pilosicoli and Escherichia coli F4 and F18 bacteria per gram faeces. The herd-diagnostic performance was (herd-level) diagnostic sensitivity =0.99, diagnostic specificity =0.80, positive predictive value =0.94 and negative predictive value =0.96. CONCLUSIONS: The pilot study suggests criteria for herd diagnosis of low pathogen diarrhoea in growing pigs. The suggested criteria should now be evaluated, and the effect of terminating antibiotic batch medication in herds identified as suffering from low pathogen diarrhoea should be explored.

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

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 log10 bacteria/g feces; P = 0.26).

Spatial and temporal patterns of pig herds diagnosed with Postweaning Multisystemic Wasting Syndrome (PMWS) during the first two years of its occurrence in Denmark.

The clinical syndrome Postweaning Multisystemic Wasting Syndrome (PMWS) in pigs has emerged globally during the last decade. In October 2001, the first pig herd diagnosed with PMWS was reported in Denmark, and since then the number of herds diagnosed with PMWS has increased markedly. The etiology of PMWS is not well understood, but increased knowledge of the causal factors is prerequisite for applying preventive interventions. In this study we described the temporal (time of diagnosis), spatial (location of herds) and spatio-temporal pattern of Danish pig herds diagnosed with PMWS during the first two years after the first herd was diagnosed, and we tested for spatial and spatio-temporal clustering using scan statistics. The study population consisted of pig herds that during the study period (October 2001-September 2003) performed diagnostic submissions to the two major veterinary diagnostic laboratories in Denmark (6724 herds). Of these, 277 herds were diagnosed with PMWS. Two statistically significant spatial clusters of herds diagnosed with PMWS were identified. These clusters included 11% and 8% of the study herds, respectively. Within these two clusters the relative risk for a herd to be diagnosed with PMWS was twice as high as expected. One statistically significant spatio-temporal cluster was identified between February and May 2002. We discuss different hypotheses that could explain why pig herds diagnosed with PMWS were clustered both spatially and spatio-temporally, and conclude that the results support the hypothesis that PMWS is caused by introduction of a new, unidentified, pathogen into the Danish pig production.