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.     

Multicausal infectious respiratory tract disease of young fattening turkeys]

The outbreak of the disease occurred in a large multiple-age farm with about 50,000 meat turkeys, where groups of 6-8000 one-day-old birds were stalled up every 14 days. All the turkey poults housed were affected mostly in the 1.-3. week of the life. The respiratory disease spread rapidly within the flocks and were characterised clinically by inclination of huddle, ruffled feathers, anorexia, stunted growth, swelling of the infraorbital sinus and nasal discharge. The clinical apparent disease lasted 3 to 4 weeks on the average in the affected flocks and were associated with a mortality from 7-20 percent. The main pathoanatomical lesions were catarrhal-fibrinopurulent rhinitis, sinusitis, tracheitis, bronchopneumonia and air sacculitis as well as atrophy of the thymus. Fibrinous adhesive peri- and epicarditis, perihepatitis, miliary necrotic foci in the liver and diarrhea have been found less frequently. The results of cultural and serological examinations of moribund and dead turkey poults of 6 different flocks indicate that Bordetella avium and Chlamydia psittaci are the primary inciting agents of the respiratory disease. However, the following severe course of the disease were mainly caused by concurrent infections with Klebsiella pneumoniae subsp. pneumoniae, Escherichia coli and Pseudomonas fluorescens. In some cases coccidiosis with lesions in ceca were additionally diagnosed. Campylobacter jejuni could be always isolated culturally from the liquid cecal content of diseased birds.     

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.     

Serologic evidence of infectious bursal disease virus serotype II infection in Minnesota turkeys

Serum samples from seven randomly selected Minnesota turkey flocks were tested for antibodies to infectious bursal disease virus serotype I (Lukert strain, isolated from chickens, and North Carolina strain, isolated from turkeys) using a virus-neutralization (VN) test. All flocks were found to have low antibody titers to both Lukert and North Carolina strains. Five out of the seven flocks had high VN titers to the Missouri strain, a serotype II virus isolated from turkeys.     

A hitherto unreported paramyxovirus of turkeys

A newly isolated avian virus is described which was obtained from a flock of laying turkey hens with respiratory disease and accompanying egg production drop. Characterisation of the virus indicated it to be of the paramyxovirus group and to be related through antigenic crossing with Newcastle disease virus. Examination of turkey sera from five separate flocks indicated natural infection with the paramyxovirus to be relatively widespread. Experimental infection of turkeys produced only mild respiratory disease.     

Isolation of a paramyxovirus-3 from turkeys with respiratory tract disease in Germany]

In fattening turkeys 2.5 weeks of age a respiratory disease associated with coughing, nasal discharge and swelling of the infraorbital sinus was seen. Pathological findings in diseased turkeys were sinusitis, tracheitis, pneumonia and aerosacculitis. Virological investigations of trachea, kidney and intestine in SPF-chicken embryos resulted in the isolation of a virus, that could be identified as a paramyxovirus type 3 due to chemical-physical, biological, morphological and immunological properties. The pathogenicity of the isolate 324/86 to turkeys was shown in a test with three weeks old turkey poults. This is the first isolation and identification of a paramyxovirus-3 of turkeys in Germany.     

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.     

Swollen head syndrome: clinical observations and serological examinations in West Germany

Swollen Head Syndrome (SHS) affects both broiler and broiler breeders and has become a problem in many countries. Clinical signs similar to those described in SHS conditions have been observed in northern Germany with the disease observed mostly in chicken broilers between 4 and 5 weeks of age and in broiler breeders between 24 and 36 weeks of age. The mortality rate in broilers has been variable from negligible to 5%. In broiler breeders, the symptoms were accompanied with a drop in egg production reaching 2-3% after 1 to 2 weeks. 422 Serum samples from 21 broiler flocks were examined for the presence of antibodies to TRT-virus using indirect ELISA tests. Antibodies were detected in 2 flocks which suffered from SHS, but not in 2 flocks showing respiratory manifestations nor in 17 apparently healthy flocks. The results obtained from testing 178 serum samples from 10 breeder flocks revealed that antibodies to TRT-virus were present in one flock with SHS signs as well as in 6 apparently healthy flocks. In addition, no antibodies were found in sera collected from 3 flocks--one with SHS and respiratory disease history; one recovered from respiratory infection and one without disease history. Examination of paired serum samples from 3 breeder flocks that suffered from typical SHS-signs collected at the onset of the disease and during the convalescent stage, as well as sera from one broiler and one breeder flocks that showed respiratory manifestations, showed that there are significant increases in the number of positive sera in the flocks with SHS symptoms. The other flocks remained free from TRT antibodies.     

Observations on Alcaligenes faecalis infection in turkeys

Experiments were initiated to study the pathogenicity of 5 Alcaligenes faecalis isolates in specific-pathogen-free poults. The isolates were recovered from commercial flocks suffering from a respiratory disease. There were no differences between cultural or biochemical characteristics of the isolates, but differences in antibiotic sensitivity were detected. All 5 isolates were capable of initiating a respiratory disease in poults similar to that seen in the early stages of turkey coryza. The infection, clinical signs, and lesions were limited to the upper part of the respiratory tract, but there were substantial differences in the severity of disease initiated by different isolates. There were also differences in the persistence of infection in the host. Secondary infections in the tracheas and sinuses were higher in poults infected with A. faecalis. The disease observed in the experimentally infected birds was milder than in 4 naturally infected flocks that also had complicating Escherichia coli infections. There was no evidence of infection with infectious bursal disease virus in 4 naturally occurring outbreaks in Ohio. It is proposed that the term turkey coryza be used to describe the disease initiated by A. faecalis.     

Alcaligenes faecalis rhinotracheitis in Manitoba turkeys

An outbreak of alcaligenes rhinotracheitis occurred on one premises housing five turkey flocks totaling 25,000 poults. Prominent findings were severe respiratory difficulty resulting from excess mucus in the nasopharynx, lachrimation, and tracheal collapse. Sinus and tracheal cultures consistently yielded Alcaligenes faecalis. An adenovirus was isolated and four flocks became positive for CELO virus by agar-gel-precipitin (AGP) tests. Mortality by flocks ranged from 4% to 48%. Treatment was unsuccessful and appeared to increase the mortality rate. The course of the disease was about 6 weeks, and recovered turkeys were marketed 1 week later than the usual date.     

Egg production drops in breeder turkeys associated with western equine encephalitis virus infection

Egg production drops associated with western equine encephalitis (WEE) virus infection occurred in three turkey breeder flocks in California during summer 1993 and again in one flock the following year. Egg production losses totaled 8.76%, 9.57%, 9.71%, and 10.12% and were accompanied by an increase in small white-shelled and shell-less eggs. The outbreaks coincided with peak WEE virus activity in the state on the basis of statistics compiled by the California Department of Health Services on seroconversion rates in sentinel chicken flocks. Paired serum samples taken 2-3 wk apart showed increased titers to WEE between acute and convalescent sera in turkeys from three affected flocks. Convalescent sera were not available for testing from the fourth flock. WEE virus was isolated from one breeder hen submitted to the diagnostic laboratory during the early stages of the outbreak.     

Hemorrhagic enteritis of turkeys in California: serologic study of hemorrhagic enteritis virus antibody with an enzyme-linked immunosorbent assay

The incidence of hemorrhagic enteritis (HE) infection in California turkeys was studied by testing 2220 turkey blood samples from 173 flocks for HE virus (HEV) antibody by the enzyme-linked immunosorbent assay (ELISA). Maternal antibody was detected at 1 day of age in all flocks tested, and it vanished after 3 weeks. Acquired HEV antibody appeared at 8 to 10 weeks, and 100% of the meat and breeder turkey flocks were positive after 11 weeks of age. HEV infection occurred earlier in the meat flocks than in the breeder flocks, and it also occurred earlier during summer than during the fall and winter months.     

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.