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.     

Isolation and molecular characterisation of chicken parvovirus from Brazilian flocks with enteric disorders

1. The presence of parvovirus in chickens with enteric disease was investigated in commercial flocks in Brazil.

2. The intestinal contents of chickens exhibiting clinical signs of diarrhoea, weight loss or mortality were examined, and chicken parvovirus (chPV) was identified using a polymerase chain reaction (PCR) assay. The samples were sequenced and inoculated into specific-pathogen-free (SPF) embryonated eggs to isolate the virus.

3. Necropsies showed that the embryos were dwarfish, haemorrhagic and oedematous. The presence of chPV was confirmed by PCR and DNA sequencing.

4. The molecular characterisation of chPV strains circulating in the Brazilian flocks showed that they were genetically related to sequences from North America, Europe and Asia. Phylogenetic analyses clustered the Brazilian chPV sequences with those from Europe (Croatia, Hungary) and Asia (South Korea).

5. This study is the first report of the molecular characterisation of chPV circulating in the commercial flocks in Brazil and indicates high genetic similarity with chPV sequences from around the world.     

Identification and phylogenetic diversity of parvovirus circulating in commercial chicken and turkey flocks in Croatia

Phylogenetic diversity of parvovirus detected in commercial chicken and turkey flocks is described. Nine chicken and six turkey flocks from Croatian farms were tested for parvovirus presence. Intestinal samples from one turkey and seven chicken flocks were found positive, and were sequenced. Natural parvovirus infection was more frequently detected in chickens than in turkeys examined in this study. Sequence analysis of 400 nucleotide fragments of the nonstructural gene (NS) showed that our sequences had more similarity with chicken parvovirus (ChPV) (92.3%-99.7%) than turkey parvovirus (TuPV) (89.5%-98.9%) strains. Phylogenetic analysis grouped our sequences in two clades. Also, the higher prevalence of ChPV than TuPV in tested flocks was defined. The necropsy findings suggested a malabsorption syndrome followed by a preascitic condition. Further research of parvovirus infection, pathogenesis, and the possibility of its association with poult enteritis and mortality syndrome (PEMS) and runting and stunting syndrome (RSS) is needed to clarify its significance as an agent of enteric disease.     

Association of Reoviridae particles in an enteric syndrome of poults observed in turkey flocks during 1988

An enteric syndrome of turkey poults, characterized by enteritis, crop mycosis, intestinal changes (pale, thin-walled ballooning with watery contents), and rickets, occurred during 1988 in 74 turkey flocks from different farms belonging to 9 California turkey growers. The flocks ranged in size from 9,000 to 120,000 birds. Pools of intestine sections from 618 birds, representing 78 field cases, were examined. Histopathological examination of the intestines showed a mild to severe atrophy with a reduced depth of crypts, which was more prominent in the distal part of the small intestine. Viral isolation attempts with primary cell cultures of chicken embryo kidney cells were negative. Examination by electron microscopy of negatively stained intestinal specimens revealed the presence of Reoviridae particles of 58.8 to 80 nm in diameter. Enzyme-linked immunosorbent assay results on the intestinal pools for mammalian and group A avian rotaviruses were negative. A statistically significant relationship was found for the presence of Reoviridae particles in the intestines of 10-21-day-old birds. Of the 7 most common pathological conditions analyzed, 2, rickets and intestinal changes (thin-walled ballooning intestine with watery contents), showed a statistically significant association with the presence of Reoviridae particles.     

Astrovirus: a cause of an enteric disease in turkey poults

Virus particles of 30 nm diameter and star-shaped morphology were detected in intestinal contents of turkey poults and were identified as astroviruses. Seventy-six intestinal samples from 65 commercial turkey flocks between 6 and 35 days of age were evaluated for the presence of astroviruses by immune electron microscopy. Astroviruses were frequently detected in intestinal samples from poults that had enteritis and diarrhea of undetermined etiology. Astroviruses were geographically widespread and were present in poults from all six operations evaluated. Astroviruses were inoculated into specific-pathogen-free poults. Changes observed in the gastrointestinal tract were: dilatated ceca containing yellowish frothy contents, gaseous fluid in the intestinal tract, and loss of tone of the intestinal tract (gut thinness). Poults experimentally inoculated with astrovirus gained significantly less body weight and absorbed significantly less D-xylose than uninoculated controls.     

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%.     

The estimated prevalence of Johne's disease infected sheep flocks in Australia

OBJECTIVE: To estimate the likely geographical distribution and flock-prevalence of ovine Johne's disease (OJD) in Australia. DESIGN: A cross-sectional study design was used. PROCEDURE: The results of abattoir surveillance for OJD carried out during 2000 were analysed to estimate the prevalence of infected flocks in three regions of New South Wales and in other States. A Bayesian approach was used to adjust apparent prevalence estimates for the assumed flock-sensitivity and flock-specificity of abattoir surveillance, and to allow for uncertainty about the true values of these measures. RESULTS: The 95% probability limits for flock-prevalence at 31 December 2000 were 0.04%-1.5%, 8%-15% and 29%-39% for low, moderate and high prevalence regions of New South Wales respectively. The other States generally had an upper 97.5% probability limit of about 1% or less. Based on these estimates about 6 to 10% of flocks in New South Wales and 2.4 to 4.4% of flocks Australia-wide are likely to be infected. CONCLUSION: This study suggests that OJD has a highly clustered distribution in Australia, and provides estimates of the prevalence of infected flocks by State or region. Based on this analysis there were probably between 2000 and 3700 infected flocks in Australia at 31 December 2000, with more than 80% of these in a relatively small geographic area of central and southern New South Wales. Some States, such as Queensland and Western Australia, may have a prevalence equal or close to 0%, however the technique used was unable to demonstrate the absence of infection in these States with the intensity of surveillance undertaken to date.     

A national survey to estimate the prevalence of Salmonella species among Canadian registered commercial turkey flocks.

In 1990-1991, a national survey was conducted to estimate the prevalence of Salmonella species among Canadian commercial turkey flocks. Two hundred and seventy flocks were randomly selected across Canada. The proportion sampled from each province was selected according to each province's share of the national turkey market. Samples, consisting of 12 pooled litter and four pooled dust samples, were used to determine the Salmonella status of the environment of each flock. Additionally, a one kilogram sample of feed was taken from each flock premise. Salmonella was recovered from environmental samples in 234/270 (86.7%) of flocks and from feed samples in 26/266 (9.8%) of flocks. Forty-eight different Salmonella serovars were isolated from flock environmental samples. The most prevalent serovars were S. anatum, S. hadar, S. agona, S. heidelberg and S. saintpaul which were isolated from 53/270 (19.6%), 49/270 (18.1%), 49/270 (18.1%), 42/270 (15.6%) and 34/270 (12.6%) flocks, respectively.     

Enteric disease in specific-pathogen-free turkey poults inoculated with a small round turkey-origin enteric virus

Four- and 5-day-old specific-pathogen-free turkey poults were inoculated orally or by contact exposure to a small round turkey-origin enteric virus. At days 4 and 8 postinoculation (PI), the orally inoculated poults had significantly lower body weight gains than control poults. Poults at day 4 (orally inoculated) and 5 (contact-exposed) PI had watery droppings, dilated thin-walled ceca filled with yellow foamy fluid, catarrhal small intestinal secretions, pale intestinal serosa, and mild lymphocytic enteritis. In addition, at day 4 PI, poults were lymphopenic, had intracytoplasmic crystalline arrays of 17.1 +/- 1.1 nm viral particles in the jejunal villar enterocytes, and had an 18-to-24-nm virus in intestinal contents. Analysis of morphometric data revealed mild shortening of villi in the duodenum and elongation of crypts in the duodenum and ileum during the late stage of the syndrome (day 8 PI). These findings suggest that the 18-to-24-nm virus can produce an enteric disease syndrome and that the acute clinical manifestation of this syndrome is not the result of morphologic change such as intestinal villus atrophy. The definitive identity of this 18-to-24-nm virus is not known; however, based on size and intracytoplasmic arrays of virus, it is most probably an enterovirus.     

Clinical outbreak of Bordetella avium infection in two turkey breeder flocks

An acute upper respiratory disease was observed in two broad-breasted white (BBW) turkey primary breeder flocks. Associated clinical signs included sneezing, depression, and a deep dry cough originating from large conducting airways. Morbidity reached approximately 15-20% of the hens in an affected house. None of the turkeys died, and total feed consumption was not affected. A minimal effect upon egg production was noticed. Sera from an acutely affected flock exhibited a marked rise in titer to Bordetella avium compared with preinfection sera samples. In Case 1, B. avium was isolated in pure culture from affected birds. In Case 2, B. avium was diagnosed by serological results and clinical signs; bacteriological examination was not attempted. The findings presented here are consistent with an acute clinical outbreak of B. avium-induced turkey rhinotracheitis (turkey coryza) in BBW turkey breeder hens.     

A survey of enteric viruses of turkey poults

Intestinal samples from 91 turkey flocks between 1 day and 5 weeks of age were examined for enteric viruses using electron microscopy and electropherotyping. These flocks originated from eight operations in six states. Individual flocks were sampled only once. At the time of sampling, 31 flocks were considered normal/healthy and 60 were considered to have enteric disease. The most frequently identified viruses from diseased flocks were astroviruses (78%) and rotavirus-like viruses (RVLVs) (67%). Far less frequent were rotaviruses (22%), atypical rotaviruses (12%), enteroviruses (5%), and reoviruses (2%). Only 10% of the samples from diseased flocks were negative, but 48% of the samples from normal/healthy flocks were negative. Astroviruses and RVLVs were far less frequent in normal/healthy flocks than in diseased flocks, but rotaviruses were identified slightly more often. No viruses were detected from flocks sampled within the first few days of life. Astrovirus infections seemed to occur at an earlier age than other virus infections. Seldom was only one type of virus identified. Astrovirus + RVLV was the most frequently identified combination in diseased flocks.     

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.     

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.     

Clinical signs and mortality caused by Ornithobacterium rhinotracheale in turkey flocks

Upper respiratory tract disease (manifesting itself in rhinitis, tracheitis and conjunctivitis) and mortality associated with Ornithobacterium rhinotracheale infection were observed in four flocks of 2- to 3-week-old turkeys. In a 15- to 16-week-old turkey flock bilateral catarrhal-croupous pneumonia was found in the dead birds. In a further 5-week-old flock and in three 16- to 20-week-old turkey flocks mortality was preceded by nervous signs (motor disturbances, recumbency, abnormal carriage of the head) and was found to be associated with fibrinopurulent inflammation of the cranial bones and meningitis. The bacterium O. rhinotracheale was isolated from the affected organs in the different disease conditions. The isolated strains did not differ markedly in cultural, morphological and biochemical properties. This is the first report of a turkey disease manifesting itself in nervous signs associated with O. rhinotracheale infection.     

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.