In 1910, H. B. Fantham described the life cycle of a coccidian parasite in birds. Fantham was a parasitologist at Cambridge University in the United Kingdom working for an enquiry into diseases affecting the red grouse. Despite the growing importance of the poultry industry and the realization that coccidiosis was an important disease of the fowl, little further work was carried out in the United Kingdom until coccidiosis research was initiated at the Veterinary Laboratory, Weybridge almost 30 yr later. Further progress depended upon research carried out at academic and agricultural institutions in the United States. E. E. Tyzzer at Harvard University provided the solid foundation upon which our present knowledge of coccidiosis, and the species of Eimeria involved in the disease, is based. Agricultural experiment stations (AESs) throughout the nation played an important role in communicating advances to the agricultural community. W. T. Johnson at Western Washington and, subsequently, Oregon AES made significant contributions to our understanding of the disease, as did C. A. Herrick and coworkers at Wisconsin AES, J. P. Delaplane and coworkers at Rhode Island AES, and P. P. Levine at Cornell University.

Abbreviation: AES = agricultural experiment station

It has been shown that Escherichia coli isolates from lesions of cellulitis belong to a limited number of clonal groups distinct from those of isolates found in the environment of these birds. In this study, different in vitro methods were used to evaluate adherence properties of E. coli isolates from cellulitis lesions and environments of high- and low-cellulitis prevalence broiler flocks. One hundred isolates were tested by hemagglutination. Adherence to frozen sections of chicken skin and binding to soluble fibronectin were examined for 40 of these 100 isolates by immunofluorescence and by immunocytofluorometry, respectively. Localization of bacterial adherence to skin tissues was confirmed by immunohistochemistry. It was demonstrated that O78:K80 isolates from cellulitis lesions adhered to skin sections to a much greater extent in deeper than in superficial tissue layers. A greater bacterial adherence following growth in TSB at 37 C was demonstrated for isolates from flocks with high prevalence of cellulitis than for isolates from flocks with low prevalence of cellulitis. MANOVA analysis results showed a significant difference between superficial and deep tissue layers only for one set of isolates from flocks with high prevalence of cellulitis. Hemagglutinating activity was variable among the O78:K80 isolates obtained from flocks with high prevalence of cellulitis. The results obtained for some O78:K80 isolates following growth in TSB suggest a role for type 1 fimbriae or F1 in adherence to skin sections. This was reinforced by the finding that adherence was inhibited by d-mannose. Poultry E. coli isolates that express F1 had no affinity for soluble fibronectin, although localization of the adherence in skin sections suggested a role for extracellular matrix components such as collagen and insoluble fibronectin.

In serum, tracheal wash fluid, and bile from chickens that were inoculated with live or inactivated Newcastle disease virus (NDV), the kinetics and immunoglobulin (Ig) class distribution of an antibody response were demonstrated. The Ig classes (IgM, IgG, and IgA) were captured using monoclonal antibodies (MAbs) in enzyme-linked immunosorbent assays (Ig-capture ELISA). The antibody specificity of the captured Ig was confirmed by binding of NDV. After inoculation with live virus, antibodies of the IgG and IgM classes were mainly found in serum. IgM was produced early from day 4 postexposure (PE) onward, IgG was detected later from day 7 PE onward, and in the tracheal wash fluid and bile, all three Ig classes were demonstrated. After inoculation of inactivated virus, a delayed response of all three classes was observed in serum, and only IgM and IgG were recognized in the tracheal fluid and bile.

The type of vaccine and the route of antigen entrance may have determined the immunoglobulin class produced. The Ig-capture ELISA assay developed in this study can be useful for evaluating various strategies to improve the efficacy of Newcastle disease vaccines and to study the evoked immune mechanisms.

A polymerase chain reaction (PCR) assay that utilizes nested primers to amplify a fragment of the long terminal repeat of exogenous avian leukosis virus (ALV) was developed and evaluated for detection of ALV subgroup J directly from clinical samples. Compilation of sequence data from different endogenous and exogenous ALVs allowed the selection of a conserved set of nested primers specific for the amplification of exogenous ALV subgroups A, B, C, D, and J and excluded amplification of endogenous viruses or endogenous viral sequences within the chicken genome. The nested primers were successfully used in both PCR and reverse transcriptase (RT)-PCR assays to detect genetically diverse ALV-J field isolates. Detection limits of ALV-J isolate ADOL-Hc1 DNA by nested PCR and RNA by RT–nested PCR were superior to detection of group-specific antigen by enzyme-linked immunosorbent assay (ELISA) in cell culture. Detection of ALV-J in cloacal swabs by RT–nested PCR was compared with direct detection by antigen-capture (ac)-ELISA; RT–nested PCR detected fewer positive samples than ac-ELISA, suggesting that RT–nested PCR excluded detection of endogenous virus in clinical samples. Detection of ALV-J in plasma samples by RT–nested PCR was compared with virus isolation in C/E chicken embryo fibroblasts; the level of agreement between both assays as applied to plasma samples ranged from low to moderate. The main disagreement between both assays was observed for a group of plasma samples found positive by RT–nested PCR and negative by virus isolation, suggesting that RT–nested PCR detected ALV-J genome in plasma samples of transiently or intermittently infected birds. ALV-J transient and intermittent infection profiles are characterized by inconsistent virus isolation responses throughout the life of a naturally infected flock.

Killed vaccines in oil emulsions are critical components of breeder and layer vaccination programs. Current vaccination sites are limited, and each has inherent problems. Oil emulsion vaccines are associated with increased condemnations of spent fowl when vaccines are injected intramuscularly into the breast. In an attempt to reduce tissue reaction when injected into the breast muscle, a commercially available Pasteurella multocida bacterin was heated to 41 C (100 F) for 5 hr prior to administration. A second treatment group was injected with the same bacterin at room temperature, 25 C. The vaccine was injected into the breast muscle at 10 and 18 wk of age into white Leghorn hens. Seroconversion was evaluated using P. multocida enzyme-linked immunosorbent assay (ELISA) at 10, 18, and 24 wk. Treatment and control groups were euthanized and lesions scored at 24 wk of age. One replicate was challenged with type 1 P. multocida at 24 wk of age. Lesion scores for the heated vaccine group were significantly lower than the room temperature vaccine. ELISA titers were not significantly different at 24 wk between the two treatment group; however, a significant rise in antibody titer was observed at 18 wk in the group that was injected with the heated vaccine. Survivability to challenge was improved in birds injected with the heated vaccine. Results suggest that heating of a P. multocida bacterin reduces local tissue reaction without having a deleterious effect on immunity as measured by ELISA and challenge.

Infectious bursal disease viruses (IBDVs) in 26 IBDV-positive bursa samples collected in Croatia during the period 1996–2000 and in two commercially available vaccines were differentiated by the presence or absence of the CfoI, SacI, SspI, StuI, and TaqI restriction sites in the 422-bp fragment of segment A of the VP2 gene (nt 732–1153). The fragments from 14 (54%) field isolates were TaqI StuI SspI and SacI− CfoI−, indicating their very virulent (vv) character. The presence of CfoI restriction site in 10 (38%) field isolates is uncommon for vvIBDV strains. It was detected in only the 88180 vvIBDV strain. Nevertheless, these isolates can be classified as vv strains according to TaqI StuI SspI SacI− restrictions. Two SacI StuI CfoI TaqI− SspI− field isolates (8%) could be classified as non-vvIBDVs. The StuI restriction is common to vvIBDV strains. However, the StuI recognition sequence is present in the F52/70 classic European and 002-73 attenuated strains as well. The SacI CfoI StuI− SspI− restrictions and the lack of the TaqI restriction at nt position 832 show that the IBDV in GUMBOKAL® IM-SPF vaccine corresponds to the attenuated and/or vaccine strains. The TaqI restriction at nt position 875 suggests that the IBDV in GUMBOKAL® SPF vaccine could belong to the mild strains.

Differences in the immunopathogenesis of several strains of infectious bursal disease virus (IBDV) were compared. The strains included a virulent virus (IBDV-IM) and three vaccine viruses that included an intermediate vaccine virus (IBDV-B2) and two mild vaccine viruses (IBDV-Lukert and IBDV-BVM). The most significant differences were found in the systemic effects of these strains. In comparison with other strains, IBDV-IM antigen was detectable for up to 8 days postinfection (PI) in lymphoid tissues that included spleen and cecal tonsils, whereas only a few IBDV-B2- and IBDV-Lukert- and no IBDV-BVM-inoculated birds had detectable IBDV antigen in these tissues. IBDV-IM induced systemic circulating nitrite levels in over 86% of the birds at days 2 and 3 PI. IBDV-IM suppressed most vigorously the splenic mitogenic response on days 3–8 PI. Among the three vaccine strains, IBDV-B2 was the most virulent of the three, inducing a significant suppression of the mitogenic response (P < 0.05) and the most vigorous lesions in the bursa of Fabricius with the highest possible lesion score of 4 at 3 days PI (P < 0.05). IBDV-BVM was the mildest strain, not inducing any detectable lesions in lymphoid tissue at the tested time points. Whereas all IBDV-BVM-inoculated and 67% and 33% of the IBDV-Lukert- and IBDV-B2-inoculated birds, respectively, had detectable IBDV antigen in the bursa at 4 days postchallenge, none of the IBDV-IM-inoculated birds was positive for IBDV by immunohistochemistry. IBDV-IM induced the highest enzyme-linked immunosorbent assay (ELISA) antibody levels detected at days 8–29 PI (P < 0.05) and the best protection against challenge virus replication in comparison with IBDV-B2 and IBDV-Lukert. Only one of five IBDV-BVM-inoculated birds developed anti-IBDV ELISA antibodies at 29 days PI, and none of the birds was protected against IBDV challenge. We speculate that better protection with more virulent strains was due to more systemic antigenic stimulation on the basis of higher replication of IBDV in extrabursal lymphoid tissues. Interestingly, IBDV-IM did not differ from IBDV-B2 and IBDV-Lukert in its ability to induce T cell accumulation in the bursa at 8 days PI and local interferon-γ induction from days 2 to 5 PI. These results suggested that the local T cell events in the bursa alone may not be indicative of a rapid and protective immune response.

Escherichia coli infections are a major problem for the poultry industry in the United States. Yet, the virulence mechanisms operative in avian E. coli are poorly understood. In the present studies, monoclonal antibodies (MAbs) have been generated that may facilitate study of the pathogenesis of avian colibacillosis. These MAbs are directed against the Iss protein because results from our laboratory have shown that the possession of iss DNA sequences is strongly correlated with the E. coli implicated in avian colibacillosis. As part of an overall effort to explore the role of iss/Iss in colibacillosis pathogenesis, Iss protein has been purified, MAbs to Iss have been generated, and the MAbs are being evaluated. B cells from mice immunized with an Iss fusion to glutathione-S-transferase produced antibodies specifically against Iss, and these cells were used to generate the MAbs. These anti-Iss MAbs, when used in western blotting assays, can be used to distinguish iss-positive and -negative E. coli isolates, suggesting that they may be useful as reagents in the detection and study of virulent avian E. coli.

From June 1999 to September 2001, 216 bursal samples from broiler farms in the United States and from countries of Latin America were submitted to the Poultry Diagnostic and Research Center at the University of Georgia for the purpose of genotyping field infectious bursal disease viruses (IBDVs). The reverse transcriptase–polymerase chain reaction (RT-PCR) was used to amplify a 248-bp product, encompassing the hypervariable region of VP2 gene. The genotyping was conducted by restriction fragment length polymorphism (RFLP) analysis with six restriction endonucleases, DraI, SacI, TaqI, Sty, BstNI, and SspI. For the 150 samples received from the United States, 125 samples (83.3%) were RT-PCR positive for the presence of IBDV. One hundred positive samples (80%) had RFLP identical to the variant Delaware E strain, whereas 10 samples (8.0%) exhibited a RFLP pattern similar to this antigenic variant. Other IBDV strains such as Grayson Laboratory strain (GLS), Lukert, PBG-98, Delaware A, and the vaccine strains Sal-1 and D-78 were also detected. Two samples exhibited a pattern similar to the standard challenge (STC) strain, and seven strains (5.6%) were not classified by RFLP. Sixty-six bursal samples previously inactivated with phenol were received from Latin American countries. IBDV strains with analyzed genotypes similar to the Lukert strain were predominantly detected in Mexico. IBDV strains similar to variant E were detected in Colombia and Ecuador. Peru and Venezuela exhibited a higher heterogeneity of IBDV strains due to the detection of classic Delaware type as well as GLS variant strains. IBDV strains detected from Brazil and Dominican Republic exhibited RFLP patterns identical to very virulent IBDV strains prevalent in several countries in Europe, Asia, and Africa.

Mycoplasma gallisepticum (MG), a reproductive/respiratory pathogen in poultry, has been implicated in suboptimum egg production and decreased hatchability. Commercial layer hens raised in a controlled environment were inoculated with the S6 strain of MG at 20 wk of age. The S6 inoculation had no effect on bird weight, egg production, digestive tract weight and length, or histopathologic lesion scores, although significant differences were noted in the lengths and weights of various portions of the reproductive tract. This study shows that S6MG inoculation does not detrimentally affect layer hen performance when in the absence of environmental stressors customary to a caged layer facility.

Campylobacter jejuni is frequently present in the intestinal tract of commercial broiler chickens, and their drinking water has been proposed to be an initial source of bacteria for newly hatched chicks. We studied three sequential commercial broiler flocks raised in a house from which we had cultured C. jejuni from the nipple waters prior to placement of the first flock. Campylobacter cells were detected by immunofluorescence in the biofilm of the drinking nipples during the weeks when the flock was colonized with C. jejuni but not during weeks when the birds were negative. Campylobacter jejuni was isolated from the drinking water during the growth of the first flock and was present in the birds from all three flocks. Randomly amplified polymorphic DNA (RAPD)–polymerase chain reaction (PCR) typing with primer OPA11 indicated that seven distinct strains were present within the broiler house. One strain found in drinking water was similar to a strain found in birds in the second flock; however, RAPD-PCR with primer HLW85 showed that the strains were not identical. These results suggest that although the watering system is a potential source of C. jejuni in broiler flocks, the waterborne strain in this study was not detected in the birds.

A geographic information system (GIS) database of the poultry industry on the Delmarva Peninsula was developed through a cooperative agreement between the Delmarva Poultry Industry, Inc., and the Virginia–Maryland Regional College of Veterinary Medicine. The purpose of this database was to facilitate disease surveillance and assist in managing the response to outbreaks and other emergencies.

Two methods of data collection were employed and are described in this paper. The first method was to visit each poultry farm and collect the latitude and longitude coordinates with a handheld global positioning system unit. The second method used property ownership information, aerial photographs, and a GIS to determine the latitude and longitude of each poultry farm. There was no significant difference between the two methods in the accuracy of the results, but there was a large difference in the amount of time and money necessary to obtain the data. These findings indicate that whereas there are many ways to obtain accurate data for a GIS database, other factors may influence which method is chosen.

A subset of farms contained within the database was visited to assess the accuracy of the locations contained within the database. Of the 240 farms visited for validation, 212 showed evidence of a functioning or previously functioning poultry operation. The corresponding error rate was 11%. This demonstrates the need to assure that the database is kept up to date to ensure that attrition among poultry growers is recorded. Several potential factors that might contribute to sources of error are discussed.

The complete coding region of hemagglutinin genes from 26 influenza A viruses of H9N2 subtype isolated from chicken flocks in China during 1996–2001 was amplified and sequenced. Sequence analysis and phylogenetic studies of H9N2 subtype viruses on the basis of data of 26 viruses in this study and 71 selected strains available in the GenBank were conducted. The results revealed that all the mainland China isolates showed high homology (94.1%–100%) and were assigned to a special sublineage in the major Eurasian lineage, in contrast to the high heterogeneity of Hong Kong SAR isolates. All the 29 mainland China isolates and six Hong Kong SAR strains also had the following common characteristics: sharing the same sequence of proteolytic cleavage site with one additional basic amino acid, RSSR, with only two exceptions; having the same amino acid motif of the receptor-binding site, YWTNV/ALY; 23 of 28 isolates bearing seven potential glycosylation sites and the remaining five having six; and sharing characteristic deduced amino acid residues Asn-183 at the receptor-binding site and Ser-130 at the potential glycosylation site. We concluded that the H9N2 subtype influenza viruses circulating in chicken flocks in China since the 1990s and Ck/HK/G9/97-like viruses isolated in Hong Kong SAR should have a common origin, whereas Qu/HK/G1/97-like viruses including human strains isolated in Hong Kong SAR might originate from other places. The available evidence also suggests that the H9N2 viruses of special lineage themselves and factors prone to secondary infections may contribute to the widespread and dominant distribution of viruses of this subtype in chicken flocks in China and other Asian countries.

High levels of dust and microorganisms are known to be associated with animal confinement rearing facilities. Many of the microorganisms are carried by dust particles, thus providing an excellent vector for horizontal disease transmission between birds.

Two environmentally controlled rooms containing female broiler breeder pullets (n = 300) were used to evaluate the effectiveness of an electrostatic space charge system (ESCS) in reducing airborne dust and gram-negative bacteria levels over an 8-wk period (starting when the birds were 10 wk old). The ESCS was used to evaluate the effectiveness of reducing airborne microorganism levels by charging airborne dust particles and causing the particles to be attracted to grounded surfaces (i.e., walls, floor, equipment). The use of the ESCS resulted in a 64% mean reduction in gram-negative bacteria. Airborne dust levels were reduced an average of 37% over a 1-wk period in the experimental room compared with the control room on the basis of samples taken every 10 min. The reductions of airborne dust and bacteria in this study are comparable with earlier results obtained with the ESCS in commercial hatching cabinets and experimental caged layer rooms, suggesting the system could also be applied to other types of enclosed animal housing.

Prevalence was estimated for Salmonella enterica serotype enteritidis (SE) in layer house environments (n = 200 layer houses) and house mice (n = 129 layer houses) in 15 states throughout the United States. Environmental swabs were collected from manure, egg belts, elevators, and walkways. Live-catch rodent traps were placed for 4–7 days. Swabs and house mice were submitted to the laboratory for bacterial culture. Overall, 7.1% of layer houses and 3.7% of mice were culture positive for SE. The highest prevalence was in the Great Lakes region of the United States, and no SE was recovered from houses or mice in the southeast region. Presence of SE in layer houses was associated with age/molting, floor reared pullets, and number of rodents trapped. Cleaning and disinfecting houses between flocks was associated with a reduced risk. The prevalence of SE in mice from environmentally positive houses was nearly four times that of mice from environmentally negative houses.

The Pennsylvania egg quality assurance program (PEQAP) has made major gains in the reduction of Salmonella enterica serotype enteritidis (S. enteritidis). However, S. enteritidis continues to be a major food safety concern for the commercial egg laying industry. Despite intensive control efforts through PEQAP, some commercial egg layer houses still remain positive for S. enteritidis.

The primary objective of this study was to determine whether S. enteritidis isolates obtained from historically environmentally S. enteritidis–positive houses were resistant to commonly used disinfectants. Archived S. enteritidis isolates (environmental, rodent, or egg) were compared with recently obtained isolates from the environment, rodents, or eggs from the same S. enteritidis–positive house. In addition, the isolates were compared with archived isolates from those premises that appeared to have eliminated S. enteritidis from their layer facilities.

The official methods of the use–dilution analysis of the Association of Official Analytical Chemists were used to evaluate each disinfectant product. Two phenolic, one quaternary ammonium, and one combination product containing quaternary ammonium and formaldehyde were evaluated, in addition to one sodium hypochlorite detergent.

All products diluted according to the manufacturers' recommendations killed the S. enteritidis isolates in this test system. There was no difference in susceptibility or resistance to the disinfectants used between the isolates from those facilities that remained S. enteritidis–positive and those that appeared to have eliminated S. enteritidis from their facility.

Domestic houseflies (Musca domestica Linnaeaus) were examined for their ability to harbor and transmit turkey coronavirus (TCV). Laboratory-reared flies were experimentally exposed to TCV by allowing flies to imbibe an inoculum comprised of turkey embryo–propagated virus (NC95 strain). TCV was detected in dissected crops from exposed flies for up to 9 hr postexposure; no virus was detected in crops of sham-exposed flies. TCV was not detected in dissected intestinal tissues collected from exposed or sham-exposed flies at any time postexposure. The potential of the housefly to directly transmit TCV to live turkey poults was examined by placing 7-day-old turkey poults in contact with TCV-exposed houseflies 3 hr after flies consumed TCV inoculum. TCV infection was detected in turkeys placed in contact with TCV-exposed flies at densities as low as one fly/bird (TCV antigens detected at 3 days post fly contact in tissues of 3/12 turkeys); however, increased rates of infection were observed with higher fly densities (TCV antigens detected in 9/12 turkeys after contact with 10 flies/bird). This study demonstrates the potential of the housefly to serve as a mechanical vector of TCV.

The VP2 hypervariable region of P97/302 local infectious bursal disease virus (IBDV) isolate was amplified by the reverse transcriptase (RT) nested polymerase chain reaction (PCR) and cloned. This region of P97/302 local isolate was sequenced and compared with eight other reported IBDV sequences. The result showed that P97/302 IBDV was most identical to the reported very virulent IBDV strains because it has amino acid substitutions at positions 222, 256, 294, and 299, which encode alanine, isoleucine, isoleucine, and serine, respectively. This region can be digested with restriction enzymes of Taq1, Sty1, Ssp1 but not with Sac1. The P97/302 isolate was then used for the optimization of RT nested PCR enzyme-linked immunosorbent assay (ELISA). The RT nested PCR ELISA was able to detect 10⁻⁴ dilution of the infected bursa homogenates and was 10 times more sensitive when compared with the agarose gel detection method. The RT nested PCR ELISA can detect up to 0.48 ng of the PCR product. The specificity of this nested PCR ELISA was also high (100%).

In order to estimate the contribution of Salmonella in the persistence of this bacterium in chicks, we compared the persistence of a Salmonella enteritidis strain and its plasmid-cured variant in a chicken asymptomatic carrier state model. After oral inoculation, colonization with the plasmid-cured strain was significantly reduced (P < 0.001) in the ceca of chicks from the third week postinoculation and persisted for a shorter period than the wild-type strain. Moreover, numbers of S. enteritidis–infected livers were also significantly lower (P < 0.01) for the plasmid-cured strain compared with the wild-type strain from the third to the seventh week postinoculation. No difference in spleen colonization was observed. These results did not correlate with any in vitro difference in attachment, entry to, or intracellular multiplication of bacteria within intestinal or macrophage avian cell lines.

The pathogenicity of serotype 8 group I avian adenovirus (GIAAV) strains (TR630 and Saga97 strains) from inclusion body hepatitis (IBH) against cyclophosphamide (CY)-treated 3-wk-old specific-pathogen-free (SPF) chickens was examined. SPF chickens were inoculated intramuscularly with 10⁷ plaque-forming units of viruses. Both strains from IBH could produce hydropericardium and mortality in CY-treated chickens as hydropericardium syndrome (HPS) that serotype 4 GIAAV strains cause, although they could not induce either hydropericardium or mortality in nontreated chickens. Histologically, hepatocytic necrosis with intranuclear inclusions, pancreatic acinar necrosis with intranuclear inclusions, and epicardial edema were seen in CY-treated chickens inoculated with GIAAV from IBH. Immunohistochemically, these inclusions were positive against GIAAV antigen. There were neither histologic lesions nor positive reactions against GIAAV antigen in nontreated chickens inoculated with GIAAV from IBH. From the present findings, pathogenic characteristics of IBH strains and HPS strains in the chickens were essentially the same.

Avian paramyxoviruses (PMVs) and avian pneumovirus (APV) belong to the family Paramyxoviridae. Antigenic relationships between PMVs were shown previously, hence, this study was designed to investigate possible antigenic relationships between APV and four avian PMVs (PMV-1, PMV-2, PMV-3, and PMV-7). Enzyme-linked immunosorbent assay (ELISA), hemagglutination inhibition (HI) test, and virus neutralization (VN) test in chicken embryos and in Vero cells were used. The HI test was performed with the PMVs as antigens against the APV and PMVs antisera. The ELISA and VN test in chicken embryos were performed with PMVs and APV antigens and antisera. The VN test in vero cells was performed with the APV as an antigen against the PMV antisera. All the viruses were isolated in the United States or Canada. No antigenic relationships between APV and the PMVs were detected by the described tests.

The isolation of four new variants or serotypes of avian infectious bronchitis virus in Italy is reported. The antigenic characteristics of these strains were investigated by cross-neutralization tests with the new isolates, Fa 6881/97, AZ 27/98, AZ 20/97, and BS 216/01; two of the most common European serotypes, AZ 23/74 and CR 88121 (793B); and the classic Massachusetts M41 serotype in association with a panel of 17 specific antisera. On the basis of the results obtained, the new isolates show relevant serologic differences. In fact, the four isolates were not neutralized by antisera against the most common European and American serotypes; the AZ 20/97 isolate was partially neutralized by FA 6881/97 antiserum but not reciprocally.

The closely related Fa 6881/97 and AZ 27/98 isolates can be considered rather diffused in our country because they have been isolated over 20 times in the last 3 yr in different parts of Italy. On the contrary, the AZ 20/97 and BS 216/01 isolates were reported only once so far.

The reverse transcription–polymerase chain reaction showed that Fa 6881/97 isolate is related to 793B isolate, whereas AZ 27/98 and BS 216/01 isolates appeared not to be related to the most common European and Massachusetts serotypes.

Clinical outbreaks of severe acute infectious bursal disease (IBD) were recorded since the mid- and late 1990s in several countries in the southeastern part of Europe. Epidemiologic data showed that both infectious bursal disease virus (IBDV)-vaccinated and IBDV-nonvaccinated chickens were affected with acute IBD and mortality up to 50% independent of the IBDV vaccination status of the appropriate parent flocks. For investigation of the causative agent of acute IBD, the variable region of VP2 was amplified, cloned, and sequenced. Nucleotide sequence analysis of polymerase chain reaction fragments showed several silent nucleotide exchanges in comparison with the sequence of the very virulent (vv) IBDV strain UK661. Also, restriction enzyme cleavage sites proposed specific for vvIBDV were present in all investigated strains. On the basis of clinical signs in affected flocks, recorded epidemiologic data, and sequence analysis, it is very likely the IBD-causing strains were of the vv phenotype.

Mycoplasma gallisepticum (MG) was used to infect chicken embryos, and scanning electron microscopy was used to examine the morphologic changes in the tracheae. Tracheae harvested from embryos infected with MG for 5 days showed extensive deciliation, surface erosion, and inflammatory cell infiltration. Embryonic tracheal explants infected with MG for 6 hr showed the same deciliation and surface erosion. The damage to the tracheal surface caused by MG at the embryonic stage might play a role in the pathogenesis of MG infection.

Newcastle disease virus (NDV)-induced damage to the embryonic chicken trachea, the tracheal explants, and red blood cells (RBCs) was studied by scanning electron microscopy. In the tracheae, NDV caused deciliation and depletion of the epithelial cells. In the tracheal explants, the same pathologic changes could be seen within 6 hr of virus infection. In RBCs, a perforation and a change in surface morphology were observed.

Staphylococcus aureus is an important opportunist that can cause superficial to life-threatening illnesses in a variety of animal species. In poultry, this organism has been implicated in osteomyelitis, synovitis, and cellulitis. Whereas most infections can be treated with antibiotics, because of the organism's propensity to acquire antimicrobial resistance, it is important to continually monitor antibiotic susceptibilities of clinical isolates. We surveyed 77 clinical poultry S. aureus isolates, collected from 1998 to 2000, for susceptibilities to a panel of 18 antimicrobial agents. Thirty-six percent of isolates were susceptible to all antibiotics. Forty-three and 16% of avian S. aureus were resistant to one and two antibiotics respectively. Staphylococcus aureus isolates were commonly resistant to tetracycline (40%; minimal inhibitory concentration [MIC]₉₀ > 32 µg/ml), lincomycin (19%; MIC₉₀ > 32 µg/ml), erythromycin (12%; MIC₉₀ > 8 µg/ml), and kanamycin (8%; MIC₉₀ < 128 µg/ml). All S. aureus isolates were susceptible to chloramphenicol, gentamicin, streptomycin, nitrofurantion, linezolid, quinupristin/dalfopristin, vancomycin, and the production antimicrobials virginiamycin, salinomycin, and flavomycin. A periodic assessment of antimicrobial susceptibilities of important avian pathogens like S. aureus will be important in helping the clinician's choice of antibiotic to control infection.

A case of cellulitis was observed in Japanese quail (Coturnix coturnix japonica) reared for commercial meat production. This condition in Japanese quail has not been reported in the literature. This incident was the first, and to date only, occurence of cellulitis in this processing plant. The cellulitis lesions were localized to the subcutis overlying the breast and inner thigh. Carcasses of processed birds and live birds from the affected farm were presented to the Poultry Diagnostic and Research Center, University of Georgia. Escherichia coli was cultured from the lesion. The affected live birds displayed lameness and had osteomyelitis. Pasteurella multocida serotype 3,4 was cultured from the liver and bone marrow of affected birds. Approximately 4.61% of the processed carcasses from the flock were condemned because of cellulitis. This represented a 10fold increase from the typical condemnation rate. Further investigation revealed birds were placed in higher than normal density; therefore, we theorize that the concurrent pasteurellosis and increased placement density resulted in the cellulitis condition.

Squamous cell carcinoma of the oropharynx and esophagus was diagnosed in an adult Japanese bantam rooster. Grossly, a cauliflowerlike mass with irregular edges was found involving the ventrolateral surfaces of the caudal portion of the oropharynx and cervical portion of the esophagus. The large volume of the mass almost occluded the lumen of the alimentary passage. Histologically, the tumor consisted of irregular cords of pleomorphic epithelial cells that showed a disorganized pattern of growth and invaded the adjacent tissues. Keratinized epithelial cells and moderate numbers of keratin pearls were readily observed. The mitotic index was low, and, although the tumor was locally invasive, we found no evidence of vascular invasion or metastasis.

Pigeon circovirus was identified by polymerase chain reaction (PCR) in young pigeons belonging to 12 different lofts. Viral DNA was extracted from formalin-fixed, paraffin-imbedded tissues containing primarily bursa and occasionally liver and spleen with a commercial kit. PCR primers were selected from a published sequence for columbid circovirus and evaluated in a PCR assay. The histopathologic examination of various tissues revealed basophilic globular intracytoplasmic inclusions in the mononuclear cells of the bursa of Fabricius and occasionally in the spleen characteristic for a circovirus. Transmission electron microscopy of a few bursas of Fabricius revealed virus particles measuring 18–21 nm. All the samples were negative by PCR for psittacine beak and feather disease (PBFD) virus and chicken infectious anemia virus. The primers for both pigeon circovirus and PBFD virus did not react in PCR with the chicken anemia virus DNA. Most of the circovirus-infected pigeons had concurrent infections of Escherichia coli, Salmonella, Pasteurella, Aspergillus, candidiasis, nematodiasis, or capillariasis.

Malignant lymphoma is a common malignancy in birds. Paraneoplastic syndromes, which are commonly observed in domestic animals, have not been reported in association with lymphoma in birds. Hypercalcemia and hyperglobulinemia were found on plasma chemistry in two Amazon parrots, which were presented with aspecific symptoms. In both cases radiography and ultrasound demonstrated signs of hepatomegaly, which proved to be due to malignant lymphoma on postmortem examination. The hypercalcemia was found to be most consistent with a paraneoplastic effect of the malignant lymphoma in these birds. The exact origin of the hyperglobulinemia remains unclear.

Eight-wk-old layer cockerels and pullets were presented to the diagnostic lab with a history of increased mortality, ruffled feathers, lameness, and recent vaccination. At necropsy, the birds had large multifocal granulomas in multiple tissues. Only light bacterial growth was seen on culture. On histopathology, a mixed population of fungi was seen within the granulomas including zygomycetes and Aspergillus, with the zygomycetes being the predominant organism. Because of the coinfection with Aspergillus and Penicillium, obtaining the zygomycetes in pure culture was unsuccessful. The source of the zygomycete fungi remains unknown; however, zygomycetes are known to be ubiquitous. Serology was performed to evaluate the flock's immune status. There was no evidence of immunosuppression caused by chicken anemia virus or bursal disease infections. No flock treatment was initiated.

This report describes an unusual presentation of severe focal necrotic tracheitis in a flock of 8-wk-old commercial turkeys. The flock was kept on a range that is located near a cotton field. The cotton field had been chemically defoliated 2 wk before the birds were submitted for necropsy. At necropsy, most of the birds had a 1-cm, yellow–white constricture in the upper third of the trachea at which the lumen was partially occluded by necrotic tissue. Microscopically, there was severe, transmural necrosis with an accumulation of inflammatory exudate in the tracheal lumen and numerous bacteria within the necrotic debris, mucosa, and lamina propria. Mixed bacteria were isolated from the trachea. No viruses were detected. Neither abnormal heavy metal concentrations in the liver nor paraquat in the respiratory tract were detected. The exact cause of this severe, necrotic tracheitis was not determined. Based on the clinical history and laboratory findings, it was concluded that a combination of a toxic irritant, possibly an aerosolized cotton defoliant, and bacterial infections were likely the cause of this lesion.

A 3-yr-old male Gouldian finch (Erythrura gouldiae) died after 2 wk of lethargy, emaciation, feather loss, and abdominal distension. The bird was housed in an aviary for breeding, but it had shown loss of fertility in the previous breeding season. Necropsy revealed a gross, firm, and yellow mass involving the left testis. Histologically, the mass was a mixed form, intratubular and diffuse, Sertoli cell tumor. Some neoplastic cells had intranuclear inclusion bodies that immunoelectron microscopy proved to be polyomavirus particle aggregates. There were no viral inclusions in other tissues. The possible role of infection in the pathogenesis of the tumor is discussed.