Paramyxovirus type 3 (PMV-3) in California turkeys: serologic study of PMV-3 antibody with an enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) was developed for detecting paramyxovirus type 3 (PMV-3) antibody. This test had a higher sensitivity than the hemagglutination-inhibition test, and no cross-reactivity with various paramyxoviruses or avian pathogens was detected when the sera were tested diluted 1:200. The incidence of PMV-3 infection in California was studied by testing 2037 turkey sera from 174 meat and breeder flocks for the presence of PMV-3 antibody using the ELISA. The age at which the infection occurs was around 5 to 8 weeks for meat flocks and 10 to 12 weeks for breeder flocks. Infection with the PMV-3, as determined serologically, was more frequent than manifested cases of disease, and 95.2% of the flocks aged over 11 weeks had PMV-3 antibody. No typical manifestations of PMV-3 disease (respiratory disease plus drop in egg production) were observed, probably because of the early infection which occurred before laying age.     

Hemorrhagic enteritis of turkeys: influence of maternal antibody and age at exposure

The effect of maternal antibody (MAB) to hemorrhagic enteritis (HE) on the response of turkeys to infection with virulent and avirulent strains of HE virus (HEV) was examined. The influence of age at exposure and treatment with HEV antibody on development of clinical HE also was studied. MAB protected poults from clinical HE for up to 6 weeks of age. MAB also interfered with vaccination against the disease for at least 5 weeks after hatching, as indicated by absence of HEV antigen in spleens and by poor seroconversion at 6 days and at 3 weeks post-vaccination, respectively. The incidence of clinical HE in MAB-negative poults was significantly higher in poults inoculated with virus at 15 days of age or older than in poults inoculated at 1-13 days of age. Further, MAB-negative poults embryonally inoculated with virulent or avirulent strains of HEV did not develop disease; these poults developed antibody and resisted challenge with virulent virus at 6 weeks of age. Poults treated with HE antibody within 1 hour of challenge or at 1, 3, or 5 weeks before challenge with virulent virus were protected against lesions and mortality induced by HEV. These results suggest that MAB may influence susceptibility of turkeys to infection with HEV for at least 5 to 6 weeks after hatching, unlike the case with most other viral infections of poultry. The results confirm that early age resistance to clinical HE is independent of MAB and suggest that such resistance persists for up to 13 days of age. The data also suggest that turkeys lacking MAB can be immunized against HE by embryo vaccination.     

Investigation of field outbreaks of turkey haemorrhagic enteritis in Hungary

Epidemiological, pathological, serological and virological investigations are reported on turkey haemorrhagic enteritis virus (THEV) infection in Hungarian turkey flocks. The pathogenesis of infection in experimentally infected turkeys and chickens, as well as the usefulness of polymerase chain reaction (PCR)/sequencing method for epidemiological investigation and for the differentiation of vaccine and field strains of THEV was also studied. Since the first recognition of the disease in Hungary in the late 1970s, until recently the disease has been diagnosed sporadically in its mild form. In the last few years (2000-2005), however, the number of outbreaks and the severity of the disease increased (9-23 affected flocks/year). Most of the outbreaks occurred at the age of 6 to 8 weeks and was complicated with Escherichia coli infection. The antibody levels to THEV in turkey flocks gradually declined till 5-7 weeks of age, and then they increased sharply due to natural infection with THEV. The immune response to vaccination (at 5 weeks of age) showed no significant antibody level increase one week postvaccination, but four weeks later the antibody level reached high values and then remained at this high level. The agar gel immunodiffusion (AGID) test to detect turkey adenovirus A (TAdV-A) antigen and PCR methods for THEV-specific DNA gave similarly positive results if spleens with pathognomonic lesions were tested; however, PCR proved to be more sensitive in cases with less characteristic pathological lesions. Nucleotide sequence alignment of PCR products amplified from Hungarian field strains and the Domermuth vaccine strain and that of the published THEV hexon sequences in GenBank database revealed slight differences between the sequences.     

Serologic evidence of infectious bursal disease virus infection in Iowa turkeys

Two infectious bursal disease viruses (IBDVs)--a cell-culture-adapted chicken strain designated Edgar strain and a recent isolate from turkeys in Missouri--were used to assay sera from 10 Iowa turkey flocks collected between 1 and 16 weeks of age. The two viruses were serologically distinct in cross-neutralization tests. For all flocks, a similar serologic pattern was found consisting of (1) low maternal antibody titers to turkey IBDV and occasionally to Edgar strain IBDV between 1 and 3 weeks of age, (2) a period of very low or no detectable titers between 3 and 7 weeks of age, and (3) sharply rising high titers to turkey IBDV with low titers to Edgar IBDV beginning at 5 to 8 weeks of age. These findings indicate that infection with IBDV of the serotype represented in this study by the turkey isolate is common in Iowa turkey flocks, whereas infection with IBDV represented by Edgar strain is uncommon. Infection occurred between 3 and 7 weeks of age during the late brooding period or after birds had been moved to an intermediate growing facility. All flocks developed complicated respiratory disease with excessive mortality caused by Escherichia coli septicemia, typically between 3 and 6 weeks of age. Although there was a temporal relationship between IBDV infection and respiratory disease, the possible role of IBDV in the process is unknown.     

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%.     

Evidence for bursal involvement in the pathogenesis of hemorrhagic enteritis of turkeys

The pathogenesis of hemorrhagic enteritis in turkey poults infected with hemorrhagic enteritis virus (HEV) at 3 days or at 2 or 5 weeks of age was compared with pathogenesis in poults that had been chemically bursectomized neonatally and exposed to cell-culture-propagated virus at 2 or 5 weeks of age. Conventional poults exposed to HEV at 2 or 5 weeks developed clinical disease, and mortality ranged from 38% to 100%. In addition to the splenic and intestinal lesions usually seen with HEV infection, the pancreas, bursa of Fabricius, and thymus were also affected. In contrast, although they were free from detectable maternal antibody, poults infected with HEV at 3 days of age failed to develop clinical disease or mortality; however, virus was demonstrated by histological and electron microscopic examinations in spleens of these poults. Neonatal chemical bursectomy completely prevented the clinical signs, gross lesions, and mortality induced by HEV in poults at 2 or 5 weeks of age. These findings strongly suggest that an intact bursa is necessary for HEV to induce disease in turkeys.     

Economic effects of clinical chicken anemia agent infection on profitable broiler production.

An outbreak of anemia dermatitis syndrome caused by chicken anemia agent (CAA) occurred in 15 broiler flocks. An average of 29% of chickens in these flocks were derived from a common breeder flock. The breeder flock had no antibody to CAA at 20 weeks of age but had seroconverted by 31 weeks. Diseased broiler flocks were derived from eggs laid by the breeder flock between 25 and 30 weeks of age. CAA infection in the breeder flock was subclinical, with no apparent effects on mortality or performance. A strategic program of therapeutic and/or prophylactic antibiotic therapy was begun in affected broiler flocks as soon as the disease was diagnosed. Nevertheless, when the cost of therapy was taken into account, affected broiler flocks had a net income 17.3% to 19.6% lower than normal flocks. Average bird weights were 3.3% to 3.5% lower in affected flocks than in unaffected flocks, and affected flocks had a significantly greater proportion of lighter birds. Average mortality in affected flocks was 2.0% to 2.3% higher than in normal flocks, with peak mortality occurring in the third week of life. There was no apparent effect on feed-conversion ratio.     

A study of the epidemiology of infectious bursal disease in poultry in Queensland, 1976–1979

The epidemiology of infectious bursal disease (IBD) was studied by serology and sometimes by visual examination of the bursa of Fabricius in poultry flocks in Queensland during 1976–1979.
Ten flocks, each of approximately 30,000 meat breeding chickens, were surveyed. All chickens had maternally-derived antibody against IBD virus (IBDV) at hatching and active antibody was not detected while the chickens were brooded on rearing farms. When distributed to breeding farms, 7 of the flocks developed antibody when 11 to 25 weeks of age. The remaining 3 flocks were vaccinated by infection of 10% of the birds and within 4 weeks more than 80% of the chickens had developed precipitating antibody to IBDV.
Blood samples of 20 to 30 broiler chickens were collected at slaughter (7 to 9 weeks of age) from each of 312 broiler flocks raised on 37 contract farms. While the samples from 21 flocks were without detectable antibody to IBDV, all serum samples for 263 flocks contained antibody. The ratio of bursal weight to bodyweight was significantly lower in birds from 144 flocks having antibody to IBDV than in birds from 10 flocks that were without detectable antibody. In sequential studies, IBDV antibody became demonstrable in 27 of 30 flocks when the chickens were one to 6 weeks of age and was accompanied by bursal atrophy.
Serological investigation of 4 flocks of layer breeding chickens on a multi-age farm at approximately monthly intervals resulted in antibody to IBDV being detected at every examination.
Serological tests and bursal examinations were carried out weekly in 2 flocks each of 4000 layer chickens between one and 20 weeks of age. Serum antibody developed in one flock at 4 weeks of age and in the other at 17 weeks of age. In both flocks, bursal atrophy occurred concurrently with the development of antibody.     

Phenotypic and genotypic characterization of Salmonella arizonae from an integrated turkey operation

Fifty cases submitted between 2000 and 2002 were selected for retrospective analysis to evaluate possible relationships between Salmonella arizonae isolated from breeder flocks, hatching eggs, and meat bird flocks belonging to a single turkey integrator. In all the meat bird cases selected for this study, arizonosis was the primary diagnosis. In birds under 1 month of age, clinical signs and pathologic changes were observed in older birds. The Salmonella arizonae isolates were analyzed by antibiotic resistance pattern and serotype and genotyped by pulsed-field gel electrophoresis (PFGE). Serotyping and PFGE yielded similar results, but the antibiotic resistance patterns did not correspond to either serotyping or PFGE typing. The presence of common pulsed-field patterns in breeder flocks, eggs, and meat bird flocks suggested that S. arizonae was being transmitted vertically from the breeder flock.     

Enzyme immunoassay studies on the serological response of turkeys to hemorrhagic enteritis virus

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies in turkey serum to hemorrhagic enteritis virus. The ELISA antigen was extracted from turkey spleens and partially purified with fluorocarbon. Antibodies were demonstrated in serum samples of breeding and meat flocks that had been naturally exposed to infection. These samples were also examined in parallel by agar-gel precipitin (AGP); most of the sera were AGP-positive. ELISA, however, was more sensitive in detecting antibodies in day-old sera that were AGP-negative. The passively acquired antibodies were no longer detected by 4 weeks of age. A brisk but short-lived secondary response was detected by ELISA in the sera of turkeys immunized with beta-propiolactone-inactivated extract of infected spleens.     

A double-antibody enzyme-linked immunosorbent assay for the detection of turkey hemorrhagic enteritis virus antibody and antigen

A highly sensitive and specific double-antibody enzyme-linked immunosorbent assay (ELISA) is described for the detection of antigen and antibody of turkey hemorrhagic enteritis virus (HEV). The assay utilizes a virus-neutralizing monoclonal antibody (MAb) to capture the antigen and turkey antiserum against HEV as the second antibody. Microtiter plates were first coated with a dilution of 1:3000 of the MAb (300 ng immunoglobulin/well) and are used for detection of both antigen and antibody. For antibody detection, MAb-coated plates were treated with an appropriate dilution of a cell-culture-propagated HEV antigen and then reacted with the test turkey serum. For detection of HEV antigen, MAb-coated plates were treated with appropriate dilutions of test antigens and then reacted with purified anti-HEV turkey immunoglobulins. The assay for HEV antibody detection was more sensitive and specific than previously described single-antibody ELISAs. Using the double-antibody ELISA, it was found that the spleen of HEV-infected turkeys harbors very high levels of antigen. Traces of HEV antigen are present in some other organs. Infectivity assay for HEV is found to be about two orders of magnitude more sensitive than the ELISA for detection of virus.     

Serologic evidence in commercial chicken and turkey flocks of infection with reticuloendotheliosis virus

A serologic survey has documented probable infection with reticuloendotheliosis (RE) virus in 21.0% of 101 layer flocks, 23.5% of 85 broiler and broiler-breeder flocks, 2.3% of 43 backyard chicken flocks, and 4.8% of 125 turkey production and breeder flocks. However, no infection was detected in 72 grandparent lines of chicken breeding stocks representing meat-type and layer strains. The existence of natural infection was further supported by isolation of RE virus from one experimental chicken flock and two commercial turkey flocks. This study supports earlier but subsequently discounted data by Aulisio and Shelokov that exposure to RE virus occurs commonly among commercial chickens in the United States, as has also been reported in other countries.     

Characteristics of fowl cholera outbreaks in turkeys in Georgia in 1986

Information was gathered from 64 cases of fowl cholera (FC) in turkey flocks through diagnostic case records, flock records, and telephone and mail surveys. Forty-five cases came from flocks of commercial turkeys, of which 15 were presented twice, and four came from mature breeder flocks. The prevalence of FC was 18.0% of commercial flocks and 14.7% of breeder flocks at risk. The average age at first diagnosis of FC was 90 days in commercial turkey flocks and 32 weeks 5 days in breeder flocks. Acute mortality was the most common presenting complaint, with a 0.37% average mortality in commercial flocks on the day of first presentation, 0.80% in commercial flocks presented a second time, and 0.43% in breeder flocks. Pasteurella multocida was cultured from 69.8% of the 361 tissue samples submitted from these cases. Novobiocin, penicillin, and chlortetracycline (CTC) had the greatest in vitro activity against isolates. Serotype 3-cross-4 was found in all 18 commercial flocks from which isolates were typed. All breeder flocks and 88.6% of commercial flocks were vaccinated before disease onset. Flocks were treated for an average of 14.3 days, most commonly with high levels of sulfadimethoxine and/or CTC. Body weights of affected birds were comparable to those of birds in unaffected flocks, but mortality and feed efficiency were worse.     

Incidence of histomonosis in turkeys in France since the bans of dimetridazole and nifursol

Between April 2003 and March 2005, 113 outbreaks of histomonosis were recorded in standard turkey farms in France, and 15 cases were recorded in turkey breeding centres. Most of the cases were in north-west France, the principal farming area for turkeys. The majority of the cases occurred during the hottest months, from April to September. Large numbers of cases occurred among birds from four to eight weeks of age, but there were some cases in three-week-old birds and some in birds up to 17 weeks of age. In most of the standard turkey flocks the mortality was less than 10 per cent, but it was above 30 per cent in nearly 20 per cent of the outbreaks. In the breeding flocks, the average mortality was 60.2 per cent. The size of the flocks, the sex of the birds and the age at which the first clinical signs appeared did not seem to influence the mortality.     

A survey for parvovirus-like virus (so-called chick anemia agent) antibodies in broiler breeders

A prospective study to survey for the presence of parvovirus-like virus (PVLV; so-called chick anemia agent) antibody in broiler breeder pullets in Georgia, North Carolina, and Florida was conducted by collecting serum samples from 52 breeder flocks that ranged in age from 1 day to 55 weeks old. Results indicated that PVLV infection was widespread. Ninety-eight percent (51/52) of chicken flocks and 62% (530/861) of chickens had PVLV antibody. Rates of antibody-positive chickens among flocks ranged from 0% to 100% and averaged 76%. Upon initial examination, the percentages of chickens positive for PVLV appeared evenly distributed with respect to several convenient age groups and geographic locations. However, compared with young chickens (less than or equal to 19 weeks old), markedly significantly lower proportions of positives were present among chickens more than 19 weeks old (P = 0.00001) or chickens 30 weeks old or more (P = 0.000004). Also, there were significant (F = 7.7, df = 3/827, P less than 0.001) differences among the rates of PVLV antibody in chickens among various companies. The relatively high rate of PVLV antibody among broiler breeder chickens helps explain the low incidence of clinical disease among their offspring.     

Detection of enteric pathogens in Turkey flocks affected with severe enteritis,in Brazil

Twenty-two flocks of turkeys affected by enteric problems, with ages between 10 and 104 days and located in the Southern region of Brazil, were surveyed for turkey by PCR for turkey astrovirus type 2 (TAstV-2), turkey coronavirus (TCoV), hemorrhagic enteritis virus (HEV), rotavirus, reovirus, Salmonella spp., and Lawsonia intracellularis (Li) infections. Eleven profiles of pathogen combination were observed. The most frequently encountered pathogen combinations were TCoV-Li, followed by TCoV-TAstV-2-Li, TCoV-TastV-2. Only TCoV was detected as the sole pathogen in three flocks. Eight and 19 flocks of the 22 were positive for TAstV-2 and TCoV, respectively. Six were positive for Salmonella spp. and L. intracellularis was detected in 12 turkey flocks. Reovirus and HEV were not detected in this survey. These results throw new light on the multiple etiology of enteritis in turkeys. The implications of these findings and their correlation with the clinical signs are comprehensively discussed, illustrating the complexity of the enteric diseases.     

Quantitation of hemorrhagic enteritis virus antigen and antibody using enzyme-linked immunosorbent assays

Enzyme-linked immunosorbent assays (ELISAs) were developed to quantitate hemorrhagic enteritis virus (HEV) antibodies in turkey sera and HEV antigens in tissue extracts. These assays were more sensitive than the commonly used agar-gel precipitin tests in detecting antigen and antibody. The antibody-ELISA was used to monitor the presence and decline of passive antibodies in turkey poults and the seroconversion of turkeys infected with HEV. The antigen-ELISA was carried out using a monoclonal antibody; this test was used to quantitate HEV antigen in experimentally infected turkeys in a time-sequence experiment. Both ELISAs measured a strong antigenic relationship between an avirulent strain (HEV-A) and a virulent strain (HEV-V).     

A Longitudinal Study of Salmonella Infection in Different Types of Turkey Flocks in Great Britain

Salmonella is, after Campylobacter, the most reported zoonotic pathogen in the EU. Poultry are a common source of infection to humans, and turkey flocks are commonly colonized with the organism. We investigated the prevalence and risk factors of Salmonella infection in 179 houses in 60 holdings representative of turkey meat and breeder production in Great Britain. From each holding, up to four houses were chosen, and two consecutive flocks per house were sampled/tested for Salmonella to investigate the persistence, elimination and introduction of Salmonella in consecutive crops. At the first sampling, the overall flock‐level Salmonella prevalence was 32.8% and 8.9% for meat and breeding flocks respectively. There was a higher prevalence of Salmonella in flocks in the rearing stage than in the fattening and breeding stages. At the first sampling, the flock‐level prevalence of Salmonella was 26.8% (95% CI: 20.7–33.7%), while the prevalence level in the subsequent flock was 20.5% (95% CI: 13.6–29.7%). No houses were positive for any of the EU‐regulated serovars. The most commonly encountered serovars were S. Kottbus and S. Kedougou. Carry‐over of infection was observed in 44.8% of the positive houses, and introduction of new infection occurred in 8.4% of houses. Data from the questionnaires and auditing of all holdings and houses were combined and used to calculate adjusted farm‐ and house‐adjusted risk factors. Significant risk factors were feed from a source other than a national compounder (OR = 2.4), feeder type other than pan feeders (OR = 2.4) and hygiene practices other than terminal cleaning and disinfection using power‐washing with sanitizer and anteroom with boot change (OR = 2.8). The study discusses the main challenges currently faced by the industry to control Salmonella in turkey production.     

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.