The importance and prevention of the horizontal as well as the vertical transmission of Ornithobacterium rhinotracheale were investigated. In our first experiment we observed that specific-pathogen-free broiler chickens that were placed in hatching incubators at a commercial turkey hatchery during hatch showed respiratory tract lesions at postmortem examination that were positive for O. rhinotracheale by bacteriology and immunohistology. It appeared that vertical transmission occurred and that horizontal transmission of O. rhinotracheale is possible. In a second experiment, the turkeys derived from vaccinated parents showed significantly fewer respiratory tract lesions at postmortem examination at 16 days of age than the birds derived from nonvaccinated parents. In a third experiment, all vaccinated young birds, regardless of the vaccination state of their parents, showed significantly fewer respiratory tract lesions at 6 wk of age. We concluded that vaccination of the breeders reduces vertical transmission and that vaccination of the progeny is needed to resist challenge at 6 wk of age.

Proper sanitation practices and the use of efficacious disinfectants in a hatchery have an effect on chick quality. Aerosol bacterial counts, egg moisture loss, hatchability, chick quality, and broiler productivity were evaluated when egg surfaces were contaminated by immersion of each egg into a broth medium containing a field isolate of Pseudomonas aeruginosa and incubated with exposure to one of three disinfectant treatments administered by fine spray: distilled water, BioSentry 904 (904), and a 1:1 ratio of 904 and ethylenediaminetetraacetic acid (EDTA)-Tris. The aerosol bacteria levels were statistically greater on day 21 of incubation in the group treated with distilled water than in those receiving disinfectants. Overall hatch of fertile eggs and egg moisture loss were comparable among all three treatments. At 1 day of age, the chicks incubated with 904 had a statistically lower yolk sac contamination rate than those incubated with 904 EDTA-Tris or distilled water. The 2-wk mortality rates, body weights, feed conversion ratios, yolk sac weights, and yolk sac contamination rates were all similar among the three treatments.

Nitric oxide (NO) is an important mediator of innate and acquired immunities. In the studies reported here, we quantified NO produced in vitro by chicken leukocytes and macrophages and in vivo during the course of experimental infection with Eimeria, the causative agent of avian coccidiosis, and identified macrophages as the primary source of inducible NO. Eimeria tenella–infected chickens produced higher levels of NO compared with noninfected controls. In Eimeria-infected animals, SC chickens produced greater amounts of NO compared with infected TK chickens, particularly in the intestinal cecum, the region of the intestine infected by E. tenella. Macrophages that were isolated from normal spleen were a major source of NO induced by interferon (IFN)-γ, lipopolysaccharide (LPS), and E. tenella sporozoites. Macrophage cell line MQ-NCSU produced high levels of NO in response to Escherichia coli or Salmonella typhi LPS, whereas the HD-11 macrophage cell line was more responsive to IFN-γ. These findings are discussed in the context of the genetic differences in SC and TK chickens that may contribute to their divergent disease phenotypes.

Discriminating viable from dead cells is of importance in the development of bacterial detection methods. A positive reverse transcriptase–polymerase chain reaction (RT-PCR) amplification signal was tested as a potential predictor of chick colonization. Some researchers have suggested that the presence of messenger RNA (mRNA) may not correlate with cell viability. Chicken colonization by cells that have positive mRNA signal but that are noncultivable would provide a correlation in cell viability and persistence of mRNA. The role of a viable but noncultivable (VBNC) form of Campylobacter spp. for colonization of poultry could be verified by such an mRNA signal. The levels of four strains of Campylobacter spp., previously isolated from poultry feces, declined progressively over time, and loss of cultivability occurred after 6 to 7 wk incubation in phosphate-buffered saline (PBS) at 4 C. Cold-stored, noncultivable and heat-inactivated (60 C for 10 min) Campylobacter spp. produced inconsistent amplified products from RT-PCR assay, depending on the target transcripts and strains used, although all fresh cultures showed mRNA signals. For the most part, signals of mRNA species from VBNC and heat-killed Campylobacter spp. AH-1, AH-2, and CH-3 persisted. RT-PCR amplification of transcripts originating from the tkt and cmp genes and a 256-base pair amplicon (from a previously described putative haem–copper oxidase) provided consistent signals, whereas transcripts from the flaA gene did not. Presumed VBNC and heat-inactivated Campylobacter spp., which produced positive mRNA signal but was not cultivable by conventional culture-based methods, did not establish colonization in the intestine of chicks 7 days after challenge. These results lead us to question the correlation between mRNA durability with cell viability as well as the significance of the VBNC cells in environmental transmission of Campylobacter spp.

The H7N2 subtype of avian influenza virus (AIV) field isolate (H7N2/chicken/PA/3779-2/97), which caused the 1997–98 AIV outbreak in Pennsylvania, was evaluated for its infectivity, length of infection, and immune response in specific-pathogen-free (SPF) chickens. The composite findings of three clinical trials with various concentrations of virus indicated that this H7N2 subtype contained minimal pathogenicity for chickens. The concentration of the virus in the inoculum proved critical in the establishment of a productive infection in a chicken. Seven-day-old SPF chickens were not infected when inoculated with 10^0.7–2.0 mean embryo lethal dose (ELD₅₀) of the H7N2 virus per bird. At this dose level, the immune response to this virus was not detected by the hemagglutination-inhibition (HI) test. Nonetheless, chickens at ages of 5 and 23 wk old tested were successfully infected when exposed to 10^4.7–5.7 ELD₅₀ of H7N2 infectious doses per bird by various routes of administration and also by direct contact. Infected birds started shedding virus as early as 2 days postinoculation, and the period of virus shedding occurred mostly within 1 or 2 wk postinoculation (WPI). This H7N2 subtype of AIV induced a measurable immune response in all birds within 2 wk after virus exposure. Antibody titers were associated with AIV infectious doses and age of exposure of birds. Challenge of these infected birds with the same H7N2 virus at 5 and 10 WPI indicated the infective virus was recoverable from cloacal swabs at 3 days postchallenge and disappeared thereafter. In these challenged birds, the antibody levels as measured by the HI test spiked within 1–2 wk.

Avian reovirus (ARV) is a disease agent that causes economic losses in the poultry industry. The available vaccines do not confer full protection. One possible reason is the existence in the field of many virulent serotypes with no cross protection. Several ARV strains have been isolated in Israel in the last few years. In this study, we investigated the diversity of the sigma C protein of ARV because this is the most variable protein in the virus and it induces the production of neutralizing antibodies. Sigma C from two virulent isolates was sequenced, cloned, and expressed. The protein sequence differed from the attenuated vaccine strain (strain 1133) but was similar to a U.S. virulent strain (strain 1733). Those differences led to a change in the antigenic index of the protein, mainly at three sites. Sera of infected birds in a field trial and of birds in a controlled experiment vaccinated with the recombinant sigma C protein showed high titers in enzyme-linked immunosorbent assay to the recombinant protein and lower titers to the attenuated vaccine strain. This means that sigma C can be used as a diagnostic tool for the detection of antibodies relevant for protection and in the future as a subunit vaccine. The results of this study highlight the need to reconsider vaccinations against ARV in terms of the strains to be used and of the method of identifying protective antibodies transferred to progeny.

Acute colonization of the crop of the domestic turkey by Salmonella enterica serovar typhimurium (ST) was examined. The influences of preharvest probiotic and prebiotic treatment with lactobaccilli and lactose on crop colonization with ST were also investigated. Prior to Salmonella challenge, poults received 2.5% lactose and Lactobacillus acidophilus (1.9 × 10⁹ organisms/liter) in the only source of drinking water from 1 day old to termination. At 3 wk old, turkey poults were challenged with ST (1.7 × 10⁸ colony-forming units [CFU]/ml) before their natural nocturnal fast to determine the potential effects of supplementation on crop colonization when the crop was engorged and subsequently undergoing emptying. Crop ingesta and tissue were collected at time points 30 min and 4, 8, and 24 hr postchallenge and ST levels were determined. High levels of ST were detected in the crop. For instance, for the poults not receiving lactose or lactobacilli, 30 min after ST challenge, there were 4.4 × 10⁷ CFU in the crop ingesta and 5.3 × 10⁵ CFU in the crop wall. Ingesta ST levels dropped dramatically to 1.0 × 10⁶ CFU after 4 hr as the crop emptied. Crop wall ST levels were steady during the nocturnal crop evacuation. Immunohistochemical staining demonstrated ST in close association with the crop epithelium. Treatment with lactose and L. acidophilus supplementation did not reduce ST colonization.

The ΔgalE, ΔpurA, and ΔaroA derivatives of avian septicemic Escherichia coli EC99 strain (O78 serogroup) were constructed with a suicide vector containing the pir-dependent R6K replicon and the sacB gene of Bacillus subtilis. The resultant isogenic mutants were stable and lacked approximately 45%, 36%, and 52% of the genes for galE, purA, and aroA, respectively. The ΔpurA and ΔaroA mutants did not grow on minimal medium, whereas the ΔgalE mutant grew on minimal medium but was sensitive to galactose-induced lysis. The reversion frequencies of all three mutants were <10⁻¹². The mutants were highly attenuated for virulence as determined by administration of approximately 10⁷ colony-forming units of each mutant to 1-day-old chicks by the subcutaneous route. Chickens were vaccinated with the mutants by spray (droplet size ∼20 μm) at 1 and 14 days of age to determine safety, immunogenicity, and efficacy. The mutants were found to be safe. Seven days after a second vaccination, immunoglobulin (Ig)Y antibodies to E. coli in serum and air sac washings were detected by enzyme-linked immunosorbent assay. In both serum and air sac washings, IgY antibodies were significantly higher in chickens vaccinated with the mutants as compared with phosphate-buffered saline–treated controls but were significantly lower compared with chickens that were vaccinated with the parent strain. In serum, but not in air sac washings, IgY antibodies were significantly lower in chickens vaccinated with the mutants compared with the parent strain. The vaccinated chickens were given infectious bronchitis virus intranasally at 17 days of age and were challenged with homologous (EC99 strain) or heterologous (O2 serogroup) E. coli 4 days later. Chickens that received wild-type EC99 strain or its mutant derivatives were protected from homologous but not from heterologous challenge. This study indicates that the ΔgalE, ΔpurA, and ΔaroA mutants are safe and moderately immunogenic but the protection conferred by the mutants is serogroup specific.

Proventriculitis in broilers causes carcass condemnation when swollen proventriculi tear during evisceration. The cause of this proventriculitis is unknown, but several infectious agents have been associated with it. One such agent, infectious bursal disease virus (IBDV), has been implicated as a cause of proventriculitis, but a direct effect of this virus on the proventriculus has not been proven. The role of IBDV in proventriculitis may be indirect as a result of its ability to cause immunosuppression. The objective of this study was to understand how immunosuppression affects the incidence of proventriculitis in broiler chickens. Immunosuppression was induced in commercial and specific-pathogen-free broiler chickens using chemicals (cyclophosphamide and cyclosporin) or virus (IBDV). All groups were then exposed to a proventricular homogenate produced from diseased birds. At 7 and 14 days postinoculation, the incidence of proventriculitis in these groups was compared to that produced by homogenate exposure in immunocompetent broilers. All birds exposed to the proventricular homogenate from diseased birds developed proventriculitis. Cyclophosphamide and IBDV, both B cell suppressors, did not significantly affect the incidence or characteristics of the proventriculitis observed, although they did have an effect on the size of the proventriculus at 7 days postinoculation. Chickens immunosuppressed with cyclosporin, a T cell suppressor, developed more severe lesions and had a higher incidence of proventriculitis. These findings indicate that both B and T cells are involved in the immune response against proventriculitis, but cell-mediated immunity appears to have a more important role in controlling the disease. IBDV affects both humoral and cellular immunity in the chicken, so although under experimental conditions it didn't have a major effect on proventriculitis, it may explain why control of IBDV in the field seems to reduce the incidence of proventriculitis.

Medicinal feed additives bacitracin, chlortetracycline (CTC), laidlomycin, lasalocid, and salinomycin inhibited the transfer of multiresistance-conferring plasmid pBR325 (Tet^r Amp^r Cp^r, 6.0 kb) into selected gram-negative strains with the use of an in vitro model. High concentrations of ampicillin-sensitive competence-pretreated Escherichia coli HB 101 cells were exposed to 10% (v/v) of 1:10 dimethyl sulfoxide/agent : water containing test mixtures for 0.5 hr prior to plasmid addition and transforming conditions. Transformation was inhibited for all antimicrobials and showed a positive association with higher concentration. Additional testing of ionophore compounds separately and in combination with bacitracin, chlortetracycline, lincomycin, roxarsone, tylosin, and virginiamycin at representative feed concentrations demonstrated 80.6% to >99.9% inhibition (P < 0.001) of resistance transfer. Bacitracin alone inhibited transformation within the range of 50–500 ppm. No increase in resistance transfer was observed when poultry-derived and reference gram-negative isolates having low or no transformation efficiency were additionally tested. The results suggest that these compounds, at relevant concentrations used in animal feed, may interfere with cell envelope–associated DNA uptake channels or other transformation competence mechanisms. Through these mechanisms, ionophores and cell membrane–interactive feed agents such as CTC and bacitracin may act to inhibit resistance transfer mechanisms within poultry and livestock.

The objective of this study was to determine the prophylactic efficacy of two commercial products, soluble vitamin E and soluble sodium salicylate (Uni-Sol^®), in an Escherichia coli respiratory challenge. The drinking water of male turkey poults was non-supplemented or supplemented with either vitamin E or Uni-Sol or a combination of both at dosages recommended by the manufacturer. There were 110 birds in each of the four treatments, housed in four floor pens per treatment. At 5 wk of age, birds in half of the pens were challenged with an air sac inoculation of approximately 50 colony-forming units of E. coli. Water treatment commenced 5 days before challenge and continued for 2 wk after challenge, when birds were necropsied. All water treatments prevented the decrease in body weight due to E. coli challenge; however, either vitamin E or Uni-Sol alone, but not the combination of the two, decreased body weight in nonchallenged controls. Either vitamin E or Uni-Sol treatment alone, but not the combination of the two, significantly decreased mortality and air sacculitis scores of challenged birds, and all treatments decreased the isolation rates of E. coli from the liver. All treatments protected liver, spleen, and bursa weights (relative to body weight) from the effects of E. coli challenge, and Uni-Sol alone or vitamin E with Uni-Sol protected relative heart weights from the effect of challenge. Uni-Sol treatment alone increased the main effect mean total leukocyte counts and the number and percent of lymphocytes. Uni-Sol in combination with vitamin E increased the number of lymphocytes of challenged birds. Uni-Sol alone decreased the main effect mean heterophil/lymphocyte ratio (H/L) ratio, whereas vitamin E alone increased the H/L ratio of challenged birds. These results indicate that treatment of turkey poults with vitamin E or Uni-Sol prior to and during the stressful events that can lead to colisepticema may decrease disease incidence and mortality.

An avian metapneumovirus (aMPV) virosome vaccine was prepared and tested for protection of turkeys by aMPV challenge. The vaccine was produced using a detergent-based (Triton X-100) extraction of aMPV subtype C followed by detergent removal with SM2 Bio-Beads. Western blot and virus-neutralization analysis confirmed that the aMPV virosomes contained both the fusion and attachment glycoproteins. Specific-pathogen-free turkeys were immunized either intranasally (IN) or intramuscularly (IM) with two doses of the aMPV virosome vaccine. Vaccination decreased clinical signs of disease following virulent challenge, and IN vaccination was superior to IM vaccination in reducing clinical signs. Decreases in viral load in the respiratory tract were observed in turkeys receiving IN vaccination with aMPV virosomes compared to unvaccinated poults. Increased virus-neutralizing antibody levels against aMPV were observed in birds vaccinated with virosomes. These results demonstrate that immunization of turkeys with aMPV virosomes can be an effective strategy for control of disease.

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.

Infections due to Escherichia coli have been costly to the poultry industry, but the exact virulence mechanisms used by these organisms to cause disease in birds remain undefined. Several factors have been shown to contribute to the virulence of avian E. coli, and many of the genes encoding these factors have been found on large conjugative plasmids. Because of the occurrence of antimicrobial resistance genes on these same plasmids, it is possible that the use of antimicrobial agents may select for persistence of E. coli containing such plasmids. In the present study, a subclone of one of these plasmids was identified as likely containing some virulence and antimicrobial resistance genes. In an effort to better understand the relationship between virulence and resistance in these plasmids, this subclone was sequenced and the sequence analyzed. Analysis of this 30-kilobase (kb) region of plasmid pTJ100 revealed a mosaic of virulence genes, insertion sequences, antimicrobial resistance cassettes, and their remnants. Many of the resistance genes found in this region were expressed under laboratory conditions, indicating that certain antimicrobial agents, including disinfectants, antibiotics, and heavy metals, could promote selection of E. coli containing such plasmids in the production environment. Also, analysis of the G C content of this clone indicated that it is the likely consequence of a complex evolution with components derived from various sources. The occurrence of many mobile elements in conjunction with antimicrobial resistance and virulence genes in this 30-kb region may indicate that the genetic constitution of the clone is quite plastic. Although further study will be required to better define this plasmid's role in avian E. coli virulence, the sequence described here is, to our knowledge, the longest known contiguous sequence of a ColV plasmid yet presented. Analysis of this sequence indicates that this clone and its parent plasmid may be important to the pathogenesis of avian colibacillosis and the evolution of avian E. coli virulence.

The effect of infectious bursal disease virus (IBDV) on Salmonella typhimurium (ST) infections in broilers was investigated in terms of Salmonella shedding and persistence, pathogenicity, and isotype specific humoral immune responses. Thirty-six, 1 day-old, straight-run commercial broiler chickens that were Salmonella negative by polymerase chain reaction (PCR) and culture were divided into two groups of 18 chicks each (ST and ST-IBDV). One group (ST-IBDV) of chicks received the E/Del strain of IBDV (10^5.0 median tissue culture infective dose [TCID₅₀]/ml) through the ocular and cloacal routes divided into doses of 50 μl each at 2 days of age. Both groups were then inoculated with 10⁸ colony-forming units (CFU)/ml nalidixic acid-resistant ST in the drinking water at 3 days of age. Environmental Salmonella counts were higher in the ST-IBDV group at 2 and 3 wk postinfection (PI) compared to the ST group. ST carriage in the cecal contents between the ST and ST-IBDV groups was not statistically different. The ST-IBDV group had a single mortality at 10 days postinfection compared to none in the ST group. The ST-IBDV group had significantly lower bursa to body weight ratios at 4 and 6 wk, as well as higher bursal lesion scores than the ST group at 2, 4, and 6 wk PI. The ST group had significant increase in serum IgG from 2 to 6 wk PI in comparison to the ST-IBDV group, which had no significant changes over time. Both IgA and IgM were significantly increased at 4 and 6 wk relative to 2-wk levels. There was an IBDV-induced failure of anti-Salmonella IgG seroconversion over time in ST-IBDV. Both groups continued to shed high levels of Salmonella up to the end of the study despite high antibody levels in the ST group and an unimpaired IgM and IgA production in the ST-IBDV group, indicating a limited influence of humoral immunity on Salmonella clearance.

Vaccination of chickens with live oocysts has become a more widely used method for controlling avian coccidiosis as resistance to anticoccidial medication increases. However, some coccidia strains are not useful in multispecies vaccines because antigenic variation has made them generally less protective. In order to experimentally test a number of strains for the best cross protection, we have devised an evaluation method using four independently measured variables: weight gain, lesion score, plasma carotenoids, and plasma NO₂⁻ NO₃⁻. These values, when measured at 6 days postchallenge, tend to be significantly correlated. A protective index (PX) is calculated for each chicken using the following algorithm: PX = (Ngain Ncarotenoids) − (Nsqrls N[NO₂⁻ NO₃⁻]), where the prefix N indicates values for a variable normalized against a mean of that variable from a control group. Nsqrls values are normalized values of the square roots of lesion scores. The PX can then be treated as a dependent variable. In this study, mean PX values of unchallenged groups cluster around 0. Mean PX values of protected chickens are statistically close to those from unchallenged groups, whereas unprotected chickens have highly negative mean PX values.

The complete coding regions of the surface glycoproteins, nucleoprotein (NP), polymerase 2 (PB2), and matrix (M) of A/turkey/214845/02 and A/turkey/220158/99 (H7N3) low pathogenicity avian influenza (LPAI) viruses isolated in October 2002 in Italy were amplified and sequenced to determine the epidemiologic relationships with an A/turkey/Italy/4603/99 (H7N1/4603/99) LPAI virus isolated during the 1999–2001 epizootic in Italy. The hemagglutinin (HA) of H7N3 viruses showed 97.8% nucleotide similarity with A/turkey/Italy/4603/99 (H7N1), and NP, M, and PB2 gene similarities were 93.6%, 98.2%, and 96.2%, respectively. Phylogenetic analyses of HA, PB2, and M genes showed that H7N3 and H7N1 viruses were closely related. Sequence analysis revealed a 23 amino acid deletion in the stalk of the neuraminidase of H7N3 viruses and a unique deletion of amino acid glycine in position 17 in the NP gene of H7N1 virus.

In vitro studies of the interaction between pathogenic bacteria and the chicken intestinal epithelium are hampered by the lack of a host- and tissue-specific in vitro model. Therefore, a reproducible method for isolation and cultivation of chicken primary cecal epithelial cells was developed. Cecal crypts were isolated and cultured in vitro to form a semiconfluent layer of epithelial cells. Incubation of Salmonella enteritidis with these cells resulted in invasion. Pretreatment of the Salmonella bacteria with butyric acid resulted in a significant decrease of invasion of the bacteria in the chicken cecal epithelial cells, whereas pretreatment with acetic acid increased invasiveness. These interactions of S. enteritidis with primary chicken cecal epithelial cells were similar to the interactions with other epithelial cell types.

Three experiments were conducted to assess mortality rate, blood chemistry, and histologic changes associated with acute exposure to T-2 mycotoxin in adult bobwhite quail. In Experiment 1, adult quail were orally dosed with T-2 toxin to determine the lethal dose that resulted in 50% mortality of the affected population (LD₅₀), and that dose was determined to be 14.7 mg of T-2 toxin per kilogram of body weight (BW). A second experiment was performed to study the effects of 12–18 mg/kg BW T-2 toxin on blood chemistry and liver enzyme profiles. Posttreatment uric acid, aspartate aminotransferase, lactic dehydrogenase, and gamma glutamyltransferase increased as compared with pretreatment values. In contrast, posttreatment plasma total protein, cholesterol, and triglyceride levels numerically decreased as compared with pretreatment values. Changes in blood chemistry values were consistent with liver and kidney damage after T-2 toxin exposure. In Experiment 3, histologic analyses of bone marrow, spleen, liver, small intestine, kidney, and heart were conducted on birds dosed in Experiment 2. Marked lymphocyte necrosis and depletion throughout the spleen, thymus, bursa, and gut-associated lymphoid tissue in the small intestine were observed in birds dosed with 15 and 18 mg/kg BW T-2 toxin. Necrosis of liver and lipid accumulation as a result of malfunctioning hepatocytes were also observed. Little or no morphologic change was observed in bone marrow and heart tissue.

The LD₅₀ for adult bobwhite quail as found in this study is two to three times higher than that reported for other species of commercial poultry. Results from these data confirm previous reports of immunosuppressive and/or cytotoxic effects of T-2 toxin in other mammalian and avian species. T-2 toxin may have a negative impact on the viability of wild quail populations.

Avian polyomavirus infection in psittacines was diagnosed in tissues by the use of polymerase chain reaction (PCR) test. The tissues used in the procedure were either formalin-fixed tissues embedded in paraffin blocks or fresh tissues (heart, liver, and spleen) collected from the psittacines during necropsy. DNA was extracted from these tissues and was tested with the published primers for avian polyomavirus VP1 gene in the PCR that yielded an amplicon of 550 base pair size, which was then visualized by electrophoresis. The amplicon size was consistent with avian polyomavirus. The PCR test was found to be an effective method for identifying avian polyomavirus infection in both formalin-fixed, paraffin-embedded and fresh tissues from psittacine birds of different age groups.

The mean duration and amplitudes of the lead II electrocardiogram were determined in the peregrine falcon (Falco peregrinus brookei) using 10 birds ranging in age from 1 to 5 yr. Electrocardiograms were performed on unanesthetized falcons in order to avoid the anesthesia effect on the electrocardiogram, by a method which seems to induce a tonic immobility–like reaction. All the falcons had a normal sinus rhythm, with a mean heart rate of 268 beats per minute. Mean durations of PR, ST, QT, and RR intervals were higher (but not statistically significant) in females than in males, except for the ST segment, with similar values in both sexes. P-wave deflections were positive in I, II, III, aVL, and aVF and negative in aVR. The normal patterns of wave forms of the QRS complexes in all leads were of QS and rS types, except for aVR and aVL, which presented an R configuration. The mean electrical axis was negative, with an average of −99.9 degrees. T-wave deflections were positive in I, II, III, and aVF leads II and negative in aVR and aVL. The data collected in this study may serve as a guide for electrocardiographic monitoring of peregrine falcons.

The characteristics of the pathogenic infectious bursal disease virus (IBDV) that infected avian species other than commercial chickens were largely unknown. In this study, by using in vivo and molecular methods, we had characterized an IBDV isolate (named 94268) isolated from an infectious bursal disease (IBD) outbreak in Malaysian village chickens—the adulterated descendant of the Southeast Asian jungle fowl (Gallus bankiva) that were commonly reared in the backyard. The 94268 isolate was grouped as the very virulent IBDV (vvIBDV) strain because it caused severe lesions and a high mortality rate in village chickens (>88%) and experimentally infected specific-pathogen-free chickens (>66%). In addition, it possessed all of the vvIBDV molecular markers in its VP2 gene. Phylogenetic analysis using distance, maximum parsimony, and maximum likelihood methods revealed that 94268 was monophyletic with other vvIBDV isolates and closely related to the Malaysian vvIBDV isolates. Given that the VP2 gene of 94268 isolate was almost identical and evolutionarily closely related to other field IBDV isolates that affected the commercial chickens, we therefore concluded that IBD infections had spread across the farm boundary. IBD infection in the village chicken may represent an important part of the IBD epidemiology because these birds could harbor the vvIBDV strain and should not be overlooked in the control and prevention of the disease.

Twelve white-tailed sea eagles (Haliaeetus albicilla groenlandicus) found dead between 1997 and 2000 in Greenland were examined to investigate the health status, including the causes of death and the burden of organochlorine contaminants and potentially toxic heavy metals. The determined causes of death were unspecific trauma (n = 6), lead poisoning (n = 2) with 36 and 26 ppm lead in the liver tissue, infectious diseases (n = 1), injuries sustained during intraspecific conflict (n = 1), and gunshot (n = 1). One lead poisoned eagle had a single lead shot pellet in its gizzard. No diagnosis could be made in one case because of decomposition of the carcass. Four of the investigated eagles were injured with lead shot or bullet fragments; one of the birds was killed with about 69 lead shots. Levels of organochlorine pesticides, polychlorinated biphenyls, mercury, and cadmium in organs were moderate. The parasite fauna consisted of one coccidian and three helminth species. The acanthocephalas Profiliocollis botulus and Corynosoma suduche as well as the nematode Stegophorus stellaepolaris are all new records for the white-tailed sea eagle.

Two isolates of Haemophilus paragallinarum were obtained from a layer chicken in México. The isolates were confirmed as H. paragallinarum by polymerase chain reaction and conventional biochemical identification. The isolates were nicotinamide adenine dinucleotide (NAD) independent—growing on blood agar without the need of a nurse colony as well as on a complex medium that lacked both NAD and chicken serum. Both isolates were pathogenic, causing the typical clinical signs of infectious coryza in susceptible chickens. One isolate was Page serovar B/Kume serovar B-1 and the other isolate was Page serovar C/Kume serovar C-2. The isolates were associated with a field outbreak that involved an egg drop of 20% over a 3-wk period and a doubling of weekly mortality (from 0.1% to 0.2%). This is the first report of NAD-independent H. paragallinarum outside South Africa and is the first time that NAD-independent H. paragallinarum of serovar B has been reported.

During 2001, a mild infectious laryngotracheitis virus (ILTV) infection occurred in broiler flocks in the southeastern United States. Clinical signs included mild tracheitis, swollen sinuses, and conjunctivitis, with no increased mortality and minimal serologic response. Infrequent intranuclear inclusion bodies with or without syncytial cell formation were observed in eyelid, trachea, and larynx and in the chorioallantoic membrane of infected embryos. Immunohistochemistry and a nested infectious laryngotracheitis polymerase chain reaction (ILT PCR) were utilized to confirm the presence of ILTV nucleic acid in fixed tissues. In addition, 2-wk-old specific-pathogen-free (SPF) birds inoculated with field material exhibited the mild signs observed in broilers in the field. Tracheal swabs and tissues taken from these SPF birds were also positive by nested ILT PCR. Restriction fragment length polymorphism analysis of ILT PCR products indicated that ILT virus associated with mild respiratory disease in the Southeast is related to the chicken embryo origin vaccine type strains.

Avian mycobacteriosis is an important disease in companion, captive, exotic, and wild birds worldwide. Mycobacterium avium is the most widely distributed and pathogenic organism causing tuberculous lesions in birds. Multiple factors including age, stress, immune status, and preexisting disease determine the pathogenicity of M. avium, and the disease can manifest itself in a variety of forms. Mycobacteriosis can cause severe losses in zoo aviaries, including the loss of rare and endangered bird species. We report a case of systemic avian mycobacteriosis in an adult, free-living male American bald eagle (Haliaeetus leucocephalus) that presented to the Diagnostic Center for Population and Animal Health in November 2003.