Pathogenicity, transmissibility, and tissue distribution of avian pneumovirus in turkey poults.

The pathogenicity, transmissibility, tissue distribution, and persistence of avian pneumovirus (APV) in turkey poults were investigated in three experiments. In the first experiment, we inoculated 2-wk-old commercial turkey poults oculonasally with APV alone or in combination with Bordetella avium. In the dually infected group, clinical signs were more severe, the virus persisted longer, the bacteria invaded more respiratory tissues, and the birds had higher antibody titer than the group exposed to APV or B. avium alone. In the second experiment, we studied the distribution of APV in different tissues in experimentally inoculated 2-wk-old commercial turkey poults. Only samples from sinuses, tracheas, and lungs were positive for APV by both reverse transcriptase-polymerase chain reaction and virus isolation. In the third experiment, we studied the ability of APV to spread among birds in 1-wk-old commercial turkey poults inoculated oculonasally. The virus was isolated and the viral RNA was detected in the inoculated and direct contact birds. The virus was not isolated, viral RNA was not detected, and no antibodies were detected in the indirect contact birds. These birds were placed in different cages in the same room where the airflow was directed from the infected toward the uninfected indirect contact group.

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.

Natural and experimental infection of turkeys with avian paramyxovirus-7.

Avian paramyxovirus-7 was isolated from a natural outbreak of respiratory tract disease in male and female commercial turkey breeder flocks. The disease spread readily between different housing complexes. The virus was isolated from affected flocks and used for experimental studies in specific-pathogen-free poults. Inoculated and contact-exposed poults developed a respiratory disease characterized by rhinitis and airsacculitis. The virus was isolated from the inoculated and contact-exposed poults, and hemagglutination inhibition antibodies were detected in exposed birds.

In-vitro antimicrobial susceptibility of Clostridium perfringens from commercial turkey and broiler chicken origin.

The minimum inhibitory concentrations (MIC) of eight antibiotics and two anticoccidial agents were determined for Clostridium perfringens strains isolated from 26 commercial broiler farms and 22 commercial turkey farms. Isolates were obtained from the intestines of birds on the farm or as the processing plant using standard culture and identification techniques. The microbroth dilution test was used to determine the MIC for each compound. Most isolates from chickens had MICs in the range of 2-16 mg/L for tilmicosin, tylosin and virginiamycin, whereas the MICs for avilamycin, avoparcin, monensin, narasin and penicillin were < or = 1 mg/L. Most strains from chickens had high MICs (> or = 64 mg/L) and appeared to be resistant to bacitracin and lincomycin. Most turkey isolates had MICs in the range of 2-16 mg/L for bacitracin, tilmicosin, tylosin and virginiamycin, with strains exhibiting MICs < or = 1 mg/L for avilamycin, avoparcin, monensin, narasin and penicillin. Several turkey isolates had MICs > or = 64 mg/L to lincomycin. No attempt was made to associate farm usage of a particular antibiotic to the antibiograms.

Genetic variation in resistance of turkeys to experimental challenge with Pasteurella multocida.

Six hundred fifty-five male and female turkeys representing four genetic lines were challenged in 10 experiments over a 3-year period with a field isolate of Pasteurella multocida. Poults were challenged at 45 days of age with 1 ml of an inoculum containing 1.2 x 10(7) bacteria per ml. The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. The number of days from exposure to severe clinical signs or death for Line F (5.8 days) differed significantly from that of Line E (8.2 days), Line RBC1 (8.0 days), and Line RBC2 (8.2 days). There were no significant differences due to sex of poult for number of days from exposure to severe clinical signs or death. Overall mortality observed was 51.2%. Mortality was highest for Line F (72.1%) and differed significantly from that of the other lines. Mortality among male poults did not differ significantly from mortality among female poults.

A small round virus associated with enteritis in turkey poults.

In a natural outbreak of enteric disease in turkey poults, Salmonella, group D rotavirus, astrovirus, and a small (18-24 nm) round virus were detected in the gut contents. Except for the small virus, the pathogenic potential of the other agents is recognized. In experiments, the small round virus was shown to be transmissible and pathogenic in specific-pathogen-free turkey poults.

Effect of hatching egg sanitizers on embryonic survival and hatchability of turkey eggs from different lines and on egg shell bacterial populations.

Three experiments were conducted to examine the effect of hatching egg sanitizers on embryonic survival, hatchability, and microbiological populations of turkey eggs. Each experiment consisted of two trials. Experiments 1 and 2 were designed to examine embryonic survival and hatchability following sanitization. Experiment 3 examined postsanitization levels of bacteria on the shell surface and inside the egg at Day 7 of incubation. In Experiment 1, formaldehyde fumigation (FF) was compared to quaternary ammonium (QA). In Trial 1, eggs of 359 hens representing 10 lines were randomly assigned to one of the two treatments. In Trial 2, 3,890 eggs produced from a cross of randombred control line (RBC2) females with commercial sire line (C) males were randomly assigned to one of the two treatments. Differences due to sanitizing treatment were nonsignificant in both trials. Line was significant for 7-day embryonic survival and hatch of surviving embryos in Trial 1. In Experiment 2, QA was compared with QA plus U.S.P. Formalin (QAF). In Trial 1, eggs of 288 hens representing 10 lines were randomly assigned to one of the two treatments. In Trial 2, 1,058 eggs produced from the cross of RBC2 females with C males were randomly assigned to one of the two treatments. Differences due to sanitizing treatment were significant only for 7-day embryonic survival in Trial 2; embryonic survival was highest for QA. Line differences in Trial 1 were significant (P less than .01) for 7-day embryonic survival and hatch of surviving embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Further characterization of the agent causing coryza in turkeys.

A total of 128 isolates of Alcaligenes faecalis, from the respiratory tract of turkeys and chickens, were identified and divided into two types designated type I and type II. Type I isolates were pathogenic in poults, hemagglutinated guinea pig red blood cells (RBCs), and did not grow on minimal essential medium (MEM) agar, and most did not grow in 6.5% NaCl broth. Type II isolates were nonpathogenic and nonhemagglutinating and grew on MEM agar, and most grew in 6.5% NaCl broth. Hemagglutination of guinea pig RBCs was a reliable characteristic for distinguishing type I from type II isolates, and it correlated with pathogenicity. In serological studies using 62 type I and 21 type II isolates, cross-reactions were observed when type I but not type II antigens were used to test antisera in the microagglutination test. Eleven bacterial isolates, different from type I and type II isolates, were urease-positive. Although frequently isolated from turkeys with coryza, these isolates were nonpathogenic and were always found in association with type I A. faecalis. Urease-positive isolates and type I and type II A. faecalis isolates were stable following 50 in vitro passages. Bordetella avium sp. nov. (the nomenclature suggested in Europe for A. faecalis) was pathogenic in poults. The colonial morphology, biochemical characteristics, and hemagglutinating activity of B. avium sp. nov. were the same as those of type I A. faecalis isolates. Based on the results of these studies, it was concluded that type I A. faecalis is the etiologic agent of turkey coryza.

Possible genetic variation in resistance of turkeys to erysipelas and fowl cholera.

Natural disease outbreaks of erysipelas and fowl cholera occurred in several lines of turkeys maintained for genetic studies. There were line differences in mortality during both outbreaks, suggesting that there is genetic variation in resistance to these diseases. A line developed by selection for increased egg production had a higher mortality rate from fowl cholera than did the randombred control line from which it was developed. Both the egg line and its control line had a lower mortality rate in the erysipelas outbreak than did a line selected for increased growth rate. Both diseases induced high mortality in a line selected for increased growth.

Infectious bursal disease virus and Alcaligenes faecalis infections in turkeys.

To determine if infectious bursal disease virus (IBDV) augments alcaligenes rhinotracheitis (ART), turkey poults were exposed to IBDV, Alcaligenes faecalis, or both IBDV and A. faecalis. In five experiments, poults exposed to IBDV alone exhibited neither signs of disease nor histopathologic lesions. Serum antibodies to IBDV were detected in poults exposed to this virus by inoculation and by direct contact with inoculated birds. Signs of ART were observed 4 to 6 days following exposure to A. faecalis. Clinical signs of ART and histopathologic lesions in the upper respiratory tract of poults exposed to both IBDV and A. faecalis were similar to those observed in poults exposed to A. faecalis alone.

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.