Risk factors associated with poult enteritis mortality syndrome-positive turkey flocks

Poult enteritis mortality syndrome (PEMS) has been an economically devastating disease in North Carolina since the early 1990s. Though much is known about the disease, many questions remain unanswered about the syndrome, including its cause, transmission of causative agent(s), and control methods. This study was designed to investigate the association between PEMS and farm management factors. A prospective longitudinal study was conducted by collecting farm data and monitoring weekly mortality in 54 commercial turkey flocks raised in PEMS-affected regions. Univariate and multivariate statistical analyses revealed that enhancing rodent control methods was negatively associated (P = 0.0228) with PEMS.     

Serological surveillance for antibodies against different avian infectious agents on turkey flocks naturally infected with turkey rhinotracheitis

Turkey Rhinotracheitis (TRT) in the state of Baden-Württemberg, Germany appears to have become endemic affecting all farms and every new restocking. In 5 meat turkey flocks, serological surveillance for antibodies to TRT-, IB- and IBD-viruses, as well as to Pasteurella multocida were carried out using ELISA tests. Furthermore, sera were examined for the presence of antibodies to avian adenovirus (CELO virus), reo- and paramyxo-viruses 1 and 3. The birds were bled at 4 week intervals starting at the first day of age through the 20th week. Serological data indicated that in all turkey flocks surveyed after natural exposure to infection, there was a significant increase to TRT antibody levels which was usually accompanied with an increase in the number of positive sera to adenovirus. In addition, no antibodies to IB- and IBD-viruses as well as to Pasteurella multocida could be detected in any of the examined sera. The results related to reo- and paramyxo-viruses 1 and 3 will also be discussed.     

Diagnosis of viral agents associated with neonatal calf diarrhea.

During this study, 134 samples have been examined for the detection of the viruses associated with neonatal calf diarrhea. The presence of Nebraska viruses (rotavirus and coronavirus) has been demonstrated by using the electron microscope and the fluorescent antibody techniques while the presence of other viruses has been detected by the observation of a cytopathic effect on monolayer cells of calf testis. The Nebraska viruses have been demonstrated in 107 (80%) out of 134 field case specimens. An association of rotaviruses and coronaviruses was found in 58 cases (54%) whilst the coronaviruses and the rotavirus were found singly in 34 cases (53%) and in 15 cases (14%) respectively. Four bovine virus diarrhea viruses, two infectious bovine rhinotracheitis viruses and two enteroviruses have also been isolated in the preceding 107 Nebraska positive specimens. For the detection of the Nebraska viruses, the fluorescent antibody techniques were more sensitive than the electron microscopy. However, those two techniques must be used simultaneously for a better detection of a greatest possible number of cases.     

Distinct serotypes of porcine rotavirus associated with diarrhea in suckling piglets in southern Quebec.

Cytopathic rotavirus strains were isolated in cell cultures from the intestinal contents of diarrheic piglets on Quebec pig farms where repeated outbreaks of enteritis occurred. All the isolates shared the common group antigens of rotaviruses as revealed by immunofluorescence and counterimmunoelectrophoresis. A hemagglutinating activity was demonstrated with human group O, porcine and guinea pig erythrocytes. At least one of the isolates was clearly distinguished from the American prototype of porcine rotavirus (strain OSU) by neutralization and hemagglutination inhibition tests; a third serotype was also suspected. By polyacrylamide gel electrophoresis of RNA, it was not possible to differentiate these isolates.     

Serological investigations on reticuloendotheliosis in turkey flocks

Four meat turkey and one turkey breeding flocks were surveyed for antibodies against reticuloendotheliosis virus (REV) at different intervals using commercial enzyme-linked immunosorbent assays. In addition, serum samples collected from 18 flocks at different ages were also tested for antibodies against REV. No antibodies were detected in any of the four meat turkey flocks that were surveyed. In the breeder flock, 20%) of tested samples from 1-day-old poults were positive. Between the fourth and 12th weeks all samples that were tested yielded negative results. At 16 weeks of age 15% of samples yielded a positive reaction, but antibodies could not be detected 4 weeks later. Examination of serum samples from 18 different flocks at various ages revealed that antibodies could be detected in five flocks. The percentage of positive sera per flock ranged between 10 and 40%.     

Disease prevalence in Georgia turkey flocks in 1986

Disease prevalence in turkeys was estimated by totaling the flock size of necropsy cases submitted to the University of Georgia in 1986 for each disease reported and comparing it with the population at risk. Fowl cholera was the most prevalent disease in both commercial tom flocks (18.0%) and breeder hen flocks (14.7%). Prevalence of colibacillosis was 15.9% in commercial tom flocks, and prevalence of aspergillosis was 8.5% in commercial tom and 4.9% in breeder hen flocks.     

Viral agents associated with poult enteritis and mortality syndrome: the role of a small round virus and a turkey coronavirus

Intestinal samples from turkey poults affected with poult enteritis and mortality syndrome (PEMS) were examined for viruses by immune electron microscopy and double-stranded RNA virus genome electropherotyping. Turkey coronavirus (TCV), avian rotaviruses, reovirus, and a yet undefined small round virus (SRV) were detected. The SRV and TCV were isolated and propagated in turkey embryos. Challenge of specific-pathogen-free turkey poults with SRV, TCV, or both resulted in mortality and clinical responses similar to those of natural PEMS. Our experiments indicate that SRV and TCV are possibly important agents in the etiology of PEMS and the combination of these infections might result in outbreaks with high mortality. The severity of clinical signs and mortality of PEMS are postulated to be partly related to the virus agents involved in individual outbreaks.     

Prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in broiler chicken and turkey flocks slaughtered in Quebec, Canada

We conducted an observational study to estimate prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in poultry. Eighty-one broiler chicken and 59 turkey flocks selected among flocks slaughtered in the province of Quebec, Canada, were included in the study. Flock status was evaluated by culturing pooled caecal contents from about 30 birds per flock. Exposure to potential risk factors was evaluated with a questionnaire. Odds ratios were computed using multivariable logistic regression.

The prevalence of Salmonella-positive flocks was 50% (95% CI: 37, 64) for chickens and 54% (95% CI: 39, 70) for turkeys, respectively. Odds of Salmonella colonization were 2.6 times greater for chicken flocks which failed to lock the chicken house permanently. In turkeys, odds of Salmonella colonization were 4.8–7.7 times greater for flocks which failed to be raised by ≤2 producers with no other visitors allowed onto the premises, or origin from a hatchery.

The prevalence of Campylobacter-positive flocks was 35% (95% CI: 22, 49) for chickens and 46% (95% CI: 30, 62) for turkeys. Odds of colonization were 4.1 times higher for chicken flocks raised on farms with professional rodent control and 5.2 times higher for flocks with manure heap >200 m from the poultry house, and also increased with the number of birds raised per year on the farm and with the age at slaughter. For turkeys, odds of Campylobacter flock colonization were 3.2 times greater in flocks having a manure heap at ≤200 m from poultry house and 4.2 times greater in flocks drinking unchlorinated water.     

A survey of skeletal disorders in five turkey flocks in Saskatchewan.

Losses due to skeletal disorders varied from 1.8 to 6.1 percent in five flocks, varying in size from 2040 to 7033 birds, of broad breasted white tom turkeys. Very little evidence of significant air-sacculitis due to Mycoplasma meleagridis was found in hatching poults or during the growing period. Major disorders causing the losses included rickets, rotated tibia, arthritis/osteomyelitis and long bone distortion. Rickets and arthritis/osteomyelitis due to infection with Staphylococcus aureus were significant problems only in one flock each, while rotated tibia caused significant losses in three flocks. Long bone distortion was the major cause of economic loss and occurred in all flocks. Possible causes of long bone distortion are briefly discussed.     

Drug use and antimicrobial resistance among Escherichia coli and Enterococcus spp. isolates from chicken and turkey flocks slaughtered in Quebec,Canada

An observational study was conducted of chicken and turkey flocks slaughtered at federal processing plants in the province of Quebec, Canada. The objectives were to estimate prevalence of drug use at hatchery and on farm and to identify antimicrobial resistance (AMR) in cecal Escherichia coli and Enterococcus spp. isolates and factors associated with AMR. Eighty-two chicken flocks and 59 turkey flocks were sampled. At the hatchery, the most used antimicrobial was ceftiofur in chickens (76% of flocks) and spectinomycin in turkeys (42% of flocks). Virginiamycin was the antimicrobial most frequently added to the feed in both chicken and turkey flocks. At least 1 E. coli isolate resistant to third-generation cephalosporins was present in all chicken flocks and in a third of turkey flocks. Resistance to tetracycline, streptomycin, and sulfisoxazole was detected in > 90% of flocks for E. coli isolates. Antimicrobial resistance (AMR) was observed to bacitracin, erythromycin, lincomycin, quinupristin-dalfopristin, and tetracycline in both chicken and turkey flocks for Enterococcus spp. isolates. No resistance to vancomycin was observed. The use of ceftiofur at hatchery was significantly associated with the proportion of ceftiofur-resistant E. coli isolates in chicken flocks. In turkey flocks, ceftiofur resistance was more frequent when turkeys were placed on litter previously used by chickens. Associations between drug use and resistance were observed with tetracycline (turkey) in E. coli isolates and with bacitracin (chicken and turkey), gentamicin (turkey), and tylosin (chicken) in Enterococcus spp. isolates. Further studies are needed to provide producers and veterinarians with alternative management practices and tools in order to reduce the use of antimicrobial feed additives in poultry.     

PCR-based detection of an emerging avian pneumovirus in US turkey flocks.

Avian pneumovirus (APV) or turkey rhinotracheitis virus (TRTV) is an important respiratory pathogen of domesticated poultry in many countries in Europe, Africa, and Asia. Until recently, the United States was considered free of APV. In late 1996, an atypical upper respiratory tract infection appeared in turkey flocks in Colorado and shortly thereafter in turkey flocks in Minnesota. An avian pneumovirus (APV-US) that was serologically distinct from the previously described TRTV was isolated as the primary cause of the new syndrome. The nucleotide sequence of a fragment of the APV-US fusion gene was determined and used to develop a polymerase chain reaction-based assay that specifically detects APV-US viral nucleic acid sequences in RNA extracts of tracheal swabs and turbinate homogenates. The assay is highly sensitive in that it can detect <0.01 TCID50 of APV. The availability of this assay enables the rapid and accurate determination of APV-US in infected poultry flocks.     

Coronaviruses associated with outbreaks of transmissible enteritis of turkeys in Quebec: hemagglutination properties and cell cultivation

Coronaviruses were observed by electron microscopy in the intestinal contents of turkeys in Quebec flocks where repeated outbreaks of enteritis occurred. Three isolates could be serially propagated in turkey embryos inoculated by the amniotic route with clarified intestinal contents. Purification and concentration of viral particles contained in intestinal contents of infected embryos were achieved by precipitation with polyethylene glycol and ultracentrifugation on sucrose density gradients. Three particle types were demonstrated: intact virions with a density of 1.18 to 1.20 g/ml and incomplete particles with densities of 1.14 and 1.24 g/ml. Hemagglutination of rabbit and guinea pig erythrocytes was demonstrated with the intact viral particles; the hemagglutinin was not dependent on incubation temperature. All the isolates were antigenically related, as shown by hemagglutination-inhibition. The turkey coronaviruses did not cross-react with antisera against coronaviruses of avian infectious bronchitis, porcine transmissible enteritis, bovine neonatal calf diarrhea, or mouse hepatitis. One of the Quebec isolates was shown to induce syncytia formation on its third passage in primary chicken-embryo kidney cell cultures. Electron-microscopic examination of infected cell-culture fluids revealed characteristics coronavirus particles identical to those found in intestinal contents of infected turkeys.     

Factors associated with productivity in Canadian sheep flocks.

A mail survey of Canadian sheep flocks registered on the Record of Performance program was conducted, and the association of management practices and diseases with productivity was studied using multiple regression techniques. The relationships between management practices and diseases of lambs which were associated with production were also investigated using discriminant analysis. Flocks in the maritimes had a lower average flock productivity than those in Ontario-Quebec and the western provinces. In purebred flocks, the average adjusted weight at 100 days of age was higher than in other types of flocks, and the prevalence of scours was lower. At the herd level, the rates of pregnancy toxemia and vaginal prolapse were associated with heavier lambs, while the average daily weight gain between 50 and 100 days of age was lower in herds affected by scours and starvation. Using pasture and bush as winter housing was also detrimental to lamb productivity. No management practices discriminated between case and control flocks for scours and starvation in lambs. It was concluded that the reasons for the geographic differences should be investigated as should the management differences between purebred and other producers. Prevention of scours and starvation in lambs should be given priority in order to increase productivity.     

Mortality patterns associated with poult enteritis mortality syndrome (PEMS) and coronaviral enteritis in turkey flocks raised in PEMS-affected regions.

Poult enteritis mortality syndrome (PEMS) is an economically devastating disease. To date, many questions about the syndrome remain unanswered, including its cause, transmission of causative agent(s), and control methods. Turkey coronavirus (TCV) infection has been associated with some outbreaks of PEMS, with areas having a higher prevalence of TCV infection also experiencing an increased incidence of PEMS. This study was designed to establish mortality patterns for flocks experiencing excess mortality and TCV infection in PEMS-affected regions and to delineate the possible role of TCV in PEMS-affected flocks. Fifty-four commercial turkey flocks on farms in areas with and without a history of TCV infection were monitored for weekly mortality and for antibodies to TCV. Flocks were chosen on the basis of placement dates and were monitored from day of placement until processing. All flocks were tested for TCV by an indirect fluorescent antibody assay. PEMS status was determined with the use of the clinical definition of mortality greater than 2% during any 3-wk period from 2 wk of age through the end of brooding due to unknown cause. Of the 54 flocks, 24 remained healthy, 23 experienced PEMS, and 7 tested positive for TCV but did not experience PEMS. Ten flocks experienced PEMS and tested positive for TCV, whereas 13 flocks experienced PEMS and did not test positive for TCV. Four health status groups were evident: healthy, PEMS positive, TCV positive, and PEMS + TCV positive. Distinct mortality patterns were seen for each of the four health status groups. Whereas TCV was associated with PEMS in 43% of PEMS cases, 13 cases (57%) of PEMS did not involve TCV. Additionally, 7 out of 17 cases of TCV (41%) did not experience excess mortality (PEMS) at any time during brooding of the flock. The results of this study indicate that TCV can be associated with PEMS but is neither necessary nor sufficient to cause PEMS.