Clostridial dermatitis of turkeys (CDT) has emerged as a major issue across most geographic regions of the United States. The prevalence and severity of dermatitis has increased over the last several years, since the time it was first reported in 1993. Cellulitis in poultry can be associated with Staphylococcus aureus or Escherichia coli, but the more recent field situation in turkeys is specifically associated with Clostridium spp. The prevalence of cellulitis is relatively low; however, the disease can be devastating in the individual flocks affected. Clostridium septicum, Clostridium perfringens, Clostridium sordelli, and S. aureus can cause cellulitis. Escherichia coli, Streptococcus spp., and other bacteria have occasionally been isolated from birds diagnosed with cellulitis. CDT appears as excessive mortality in older birds around 16–18 weeks of age. It has been reported from field experience as early as 7 wk of age. Clinical signs of CDT can range from sudden death to inappetence, depression, leg weakness, recumbency, and ataxia. The disease is characterized by reddish to dark or greenish discoloration of the skin around the thighs, abdomen, keel, tail region, back, and wings. The lesions can extend into the underlying muscles, and there can be gas bubbles under the skin which result in crepitation. Some cases present with dead birds having “bubbly tail,” fluid-filled blisters associated with broken feather follicles around the base of the tail. Bubbly tail in breeder toms might not cause excessive mortality, but the lesions are so severe that the birds cannot be used for semen collection. Incidence of mortality from this condition can be severe and acute (i.e., rapid onset of high mortality). The dead birds decompose very quickly. Microscopically, there is necrosis, with or without inflammation of the skin, especially in the dermis and occasionally in the skeletal muscles, associated with large numbers of rod-shaped bacteria. Overcrowding, aggressive birds, poor–wet litter, decreased down time, a contaminated environment including feed and water, poor hygienic conditions, and contaminated vaccines and vaccine equipment, etc., can predispose birds for CDT. Preventative measures and treatment are discussed extensively in this review.

The role of Clostridium perfringens and Clostridium septicum in the development of cellulitis and mortality in turkey poults was examined. Studies were done in turkeys of two age groups: 3-wk-old and 7-wk-old turkey poults. The effect of varying doses of C. perfringens and C. septicum in reproducing cellulitis lesions and mortality in turkeys was investigated. Both in vitro and in vivo assays were conducted to study their toxic and biologic activities. Clostridium septicum spore culture was found to be more potent than that of C. perfringens in both in vitro assays, such as the hemolysis test, and in vivo assays in mice and turkeys. Both C. perfringens and C. septicum spore cultures were found to be capable of inducing cellulitis lesions and mortality in turkey poults when inoculated by subcutaneous route. Histopathology examination of affected tissues revealed a “moth-eaten appearance,” with abundant growth of C. perfringens and C. septicum in the sarcomeres of muscle tissues and in the subcutaneous tissues. However, C. septicum was found to be more potent than C. perfringens in causing cellulitis lesions and mortality in turkeys. Three-week-old poults were found to be less susceptible than 7-wk-old poults in the development of cellulitis lesions and mortality after inoculation with either spore cultures of C. perfringens or C. septicum. The results of the current study suggest that although C. septicum is more potent in causing cellulitis lesions and mortality, infection with either C. septicum or C. perfringens can cause cellulitis lesions and mortality in turkeys.

Interferon (IFN)-induced antiviral activity in cells forms an important early line of defense against viral pathogens. IFN-induced mediators are well documented in mammals, with one of the best-characterized antiviral proteins being Mx. In chickens, many alleles of Mx have been described, but functionally only the polymorphism at a site encoding residue 631 in the protein determines differential antiviral activity against vesicular stomatitis virus and influenza virus in transfection experiments. The role of chicken Mx has not been assessed with regard to infectious bursal disease virus (IBDV), an important pathogen of chickens. To examine the role of chicken IFNα and the Mx631 single-nucleotide polymorphism against IBDV, chicken embryo fibroblast cultures (CEF) that differed in Mx genotype (antivirally positive Mx Asn631 or antivirally negative Mx Ser631) were treated with IFNα and viral yield was assessed following infection with D78 vaccine-strain IBDV. IFNα was shown to have strong antiviral activity in this system in terms of reduced virus yield. Furthermore, the reduction in viral yield did not differ significantly among Mx genotypes, indicating that Mx Asn631 is not a pivotal determinant of resistance to this strain of IBDV in CEF.

Arkansas (Ark)-type infectious bronchitis virus (IBV) subpopulations with an S gene sequence distinct from the vaccine predominant consensus were previously found in the upper respiratory tract of chickens within 3 days after inoculation. This finding indicated that a distinct virus subpopulation was rapidly positively selected by the chicken upper respiratory tract. We hypothesized that during host invasion, the replicating IBV population further changes as it confronts the distinct environments of different tissues, leading to selection of the most fit population. We inoculated 15-day-old chickens with 10⁴ 50% embryo infective doses of an Ark-type IBV commercial vaccine via the ocular and nasal routes and characterized the sequences of the S1 gene of IBV contained in tear fluid, trachea, and reproductive tract of individual chickens at different times postinoculation. The predominant IBV phenotype contained in the vaccine (before inoculation) became a minor or nondetectable population at all times in all tissues after replication in the majority of the chickens, corroborating our previous findings. Five new predominant populations designated component (C) 1 through C5, showing distinct nonsynonymous changes, i.e., nucleotide changes resulting in different amino acids encoded and thus in a phenotypic change of the predominant virus population, were detected in the tissues or fluids of individual vaccinated chickens. Due to the different biochemical properties of some amino acids that changed in the S1 glycoprotein, we anticipate that phenotypic shift occurred during the invasion process. Significant differences were detected in the incidence of some distinct IBV predominant populations in tissues and fluids; e.g., phenotype C1 showed the highest incidence in the reproductive tract of the chickens, achieving a significant difference versus its incidence in the trachea (P < 0.05). These results indicate for the first time that IBV undergoes intraspatial variation during host invasion, i.e., the dominant genotype/phenotype further changes during host invasion as the microenvironment of distinct tissues exerts selective pressure on the replicating virus population.

The objective of this study was to identify environmental characteristics of European Ramsar wetlands, which are natural habitats for waterbirds, that could have contributed as risk factors for H5N1 HPAI (highly pathogenic avian influenza) in water birds (2006–2009). Ramsar wetlands in which H5N1 outbreaks were reported were considered infected (positive), and a case-control study was conducted using a logistic regression model in order to identify environmental risk factors associated with disease. Forestry (odds ratio, OR  =  6.90) and important area for water birds with mixosaline water (OR  =  6.31), as well as distance to the nearest positive wetland (OR  =  0.66), which was included into the model to adjust for spatial dependence, were associated with status of the wetlands. The model was used to estimate the risk for H5N1 HPAI on each European Ramsar wetland. Results will help to identify wetlands at high risk for H5N1 HPAI infection, wetlands that could be selectively targeted as part of a surveillance program aimed at early detection and prevention of future H5N1 HPAI epidemics.

To trace the endemic situation of highly pathogenic influenza H5N1 virus in wildlife in the Lake Qinghai area of northwest China, a continuous surveillance program was implemented from September 2005 to September 2007. A total of 2699 field samples were collected, and 95 of the samples were positive by a reverse transcription–polymerase chain reaction (RT-PCR) test of subtype H5 influenza virus. To some extent, the detection rate correlated with the species, the location, and the seasons of collection. In 2007, two H5N1 isolates were identified from two species of migratory birds. The two 2007 isolates showed high similarities of the hemagglutinin and neuraminidase genes with those of the 2005 and 2006 Qinghai isolates (98.6–99.8% for HA and 98.7–98.9% for NA at the nucleotide level). Both isolates fell into clade 2.2.2 and were experimentally highly pathogenic to chickens and mice. According to our surveillance results, HPAI H5N1 viruses still exist in this region.

Studies are limited on evaluating the potential of influenza viruses for egg-borne dissemination. In our previous studies, experimental infection of breeder turkeys with A/turkey/Ohio/313053/04 resulted in drastic declines in egg production, and we confirmed high levels of virus replication and an abundant distribution of avian-specific α2,3 sialic acid-gal receptors in the oviduct of these turkeys. In the present study, following experimental inoculation of A/turkey/Ohio/313053/04 in breeder turkeys, we detected these viruses in the albumin of eggs using real-time RT-PCR (RRT-PCR) and virus isolation in embryonated chicken eggs. Swabs from egg shells were also found positive by RRT-PCR. This is the first report of the detection of low pathogenic influenza viruses from internal egg contents following experimental infection. The possibility of hatchery contamination by egg-borne influenza viruses, and the spread of virus during movement of contaminated cracked eggs and egg flats, pose concerns regarding viral dissemination of influenza.

Challenge infections with 10³, 5 × 10⁴, 10⁵, or 5 × 10⁵ sporulated Eimeria praecox oocysts caused moderate but significant weight gain reduction at all infective doses. Substantial reduction in plasma carotenoids and moderate but significant increases in plasma were observed only at the two higher doses when measured at day 6 postchallenge (PC). Daily monitoring of chickens after challenge with 5 × 10⁴ oocysts revealed an inflammatory response in the duodenum and jejunum beginning at day 1 PC that was associated with a significant increase in levels of plasma , which peaked at day 4 PC. A moderate, uniform hyperplasia of the small intestine and significant depression of plasma carotenoids were observed on days 4–6 PC. Plasma decreased to control levels by day 6 PC. All infections were accompanied by production of a mucoid exudate in the duodenum and jejunum, which became thick and opaque by 4 days PC and tended to obscure mildly inflamed areas. These observations indicate that the acute host response to primary infection with E. praecox is both different from and occurs earlier than the response to experimental infections with other Eimeria spp., such as Eimeria acervulina, Eimeria maxima, or Eimeria tenella. These factors need to be considered in observations of pathology arising from co-infections of E. praecox with other Eimeria species, especially in drug sensitivity testing of Eimeria oocysts recovered from litter and in the evaluation of live oocyst vaccines.

Live broiler chickens are important in the transmission of Salmonella to humans. Reducing Salmonella levels in the intestine of broiler chickens, in part, requires understanding of the interactions between Salmonella and the intestinal barriers that represent the first line of defense. Such barriers include the mucus layer (composed of mucins secreted by goblet cells) and the underlying epithelium. Two experiments were conducted to evaluate the effect of Salmonella Typhimurium infection on intestinal goblet cell dynamics (density and size) and villous morphology in broiler chicks. In Experiment 1, broiler chicks were either challenged with sterile media (control treatment) or orally given 7.4 × 10⁷ colony-forming units (CFU) at 3 days of age (termed the CST treatment). Treatments were similar in Experiment 2, except that chicks in the CST treatment were challenged with 7.8 × 10⁶ CFU at 4 days of age. Duration of each experiment was 14 days. At 7 days postchallenge (PC) in Experiment 1, jejunal tissue sections were collected, formalin-fixed, and routinely processed for histologic measurement of villous morphometric indices. In Experiment 2, at 10 days PC, jejunal tissue sections were collected and processed for histologic determination of goblet cell numbers and size, in addition to villous measurements. Results showed that Salmonella Typhimurium infection increased goblet cell density, reduced villous surface area, increased the incidence of epithelial exfoliation, and increased the incidence of heterophil influx into the lamina propria (P < 0.05). It was concluded that Salmonella Typhimurium infection impacts goblet cell biology and exerts morphopathologic changes in the jejunum of broiler chicks.

We have previously demonstrated a high incidence of chickens with persistent viremia even in the presence of neutralizing antibodies (V A ) against the inoculated parental virus in commercial meat-type chickens inoculated at hatch with subgroup J avian leukosis virus (ALV J) field isolates. In this study, we used an ALV J molecular clone, ADOL pR5-4, to determine the role of neutralizing antibody (NAb) escape mutants in maintaining a high incidence of viral persistence, namely, V A infection profile in commercial meat-type chickens. Chickens were housed as a flock in a pen or housed in isolation in solitary Horsfall-Bauer units for testing for NAb escape variants. The emergence of NAb escape variants was evaluated by sequential autologous virus neutralization (VN) (between virus and antibody from the same sampling period) and heterologous VN (between virus and antibody from preceding and succeeding sampling periods). Sequential virus isolates and corresponding antisera from 18 chickens were examined by VN matrix. In all chickens, autologous virus isolates were not neutralized by corresponding antisera. However, some of these resilient autologous virus isolates were neutralized by antibodies from subsequent sampling intervals. Nucleotide sequence analysis of consecutive isolates from three individually housed chickens with V A infection profile revealed distinct changes within the envelope region, suggesting viral evolution to escape the host immune response. These results demonstrate that the emergence of antibody escape variants in commercial meat-type chickens contributes to ALV J persistence.

Leghorn hens were infected with Salmonella Enteritidis cultures of known genomic content and subpopulation characteristics to determine comparative abilities to colonize the avian reproductive tract. Group 1 received phage-type (PT)4 22079, which is a dimorphic subpopulation that can both contaminate eggs and form biofilm. Group 2 received a 90:10 mixture of monomorphic PT13a strains 21027 and 21046, which produce biofilm or contaminate eggs, respectively. Group 3 received a 10:90 mixture of the same two PT13a strains, respectively. Trials were repeated three times and a total of 30 hens per treatment group were infected. Dosage was by oral gavage and was calculated as 8.6 ± 2.01 × 10⁷ colony-forming units per hen. Liver, spleen, and three different sections of oviduct (ovary, upper oviduct, and lower oviduct) were cultured per bird. Results were that all three groups had livers and spleens that were mostly positive (90.0% and 94.4% of 270 hens cultured, respectively). Reproductive-tract organs yielded 75 positives from 270 hens (27.8%), and treatment groups ranged from a low of 6.7% to a high of 76.7% positive cultures in any one trial. There was no significant difference between the numbers of positive reproductive-tract samples between treatment groups due to variance. These results suggest that the status of the reproductive tract at the time of infection may impact recovery of culture-positive tissue and contribute to variance. It is suggested that Salmonella Enteritidis cultures that vary in subpopulation composition have subtle differences in colonization of reproductive tissue that contribute to variance in egg contamination. Culture of non–reproductive-tract organs such as the liver and spleen was overall more reliable for detection of infected hens. The spleen was especially useful for detection because of its small size. Further research is needed to determine how sex hormones influence the infection pathway that results in egg contamination.

The Marek's disease virus (MDV) induces T-cell tumors in susceptible chickens. Of the 80 to 100 known MDV genes, only the MDV MEQ gene was shown to have transforming properties. Further evidence that MEQ is probably the principal oncogene in MDV came when researchers used overlapping cosmid clones of MDV and demonstrated that deleting MEQ resulted in a highly protective Marek's disease (MD) vaccine. We deleted both copies of MEQ from a bacterial artificial chromosome clone (BAC) of MDV. The virus, BACdelMEQ, was completely attenuated and did not appear to have any adverse effect on chicken body weight in MDV maternal-antibody-positive chickens, as measured at 8 wk of age. In two protection studies, BACdelMEQ efficiently protected susceptible chickens from a challenge by MDV strain 686, one of the most virulent MDV strains. In both protection studies, the BACdelMEQ protected chickens significantly better than the commercial MD vaccine, CVI988/Rispens. Only the protein-coding sequences of MEQ were deleted and all upstream and downstream regulatory sequences were left intact. Thus, BACdelMEQ has the potential to be a superior MD vaccine as well as a vector to deliver various foreign genes to poultry.

In the present study, the hemagglutinin genes from 12 influenza viruses of the H9N2 subtype were isolated from chicken flocks in different provinces of Iran from 2003 to 2005, amplified and sequenced. All of the 12 isolates showed similar sequences at the cleavage site, RSSF/GLF, bearing eight potential glycosylation sites and sharing the characteristic deduced amino acid residues alanine-190, glutamine-226, and glutamine-227 at the receptor-binding site. Ten out of these 12 isolates possessed leucine at position 226, which prevails in the sequences found in human H2 and H3 strains. Overall, the presence in these Iranian poultry H9N2 viruses of the sequence known to bind to human-type receptors and the presence of antibodies in the human population of Iran to H9N2 showed that it is possible for circulating H9N2 avian influenza viruses in Iran to infect humans. Hence, extensive surveillance of H9N2 in this country is highly recommended.

After the spread of H5N1 highly pathogenic avian influenza virus (AIV) from Asia into Russia, the Middle East, Europe, and Africa in 2005–06, the Swiss national AIV surveillance program was extended. One of the new focal points was Lake Constance, where sentinel duck stations and swim-in traps were established within the project Constanze in collaboration with Germany and Austria. More than 2000 samples from 41 species were collected in Switzerland between September 2006 and December 2008. Approximately 4% were AIV-positive by quantitative reverse transcriptase–PCR. Subsequent typing revealed 13 different AIV subtypes, of which H5N2 and H9N2 were the most prevalent. All H7 isolates and all but one H5 isolate were characterized as low pathogenic; however, a highly pathogenic H5N1 AIV was detected in a healthy pochard. This study demonstrates that a wide selection of different AIV subtypes can cocirculate among the waterfowl population in wild bird habitats.

During the surveillance of avian influenza, an H5N2 influenza A virus was isolated from a cloacal swab sample of an apparently healthy chicken in Taiwan in October 2008. It was found that the HA of the virus had a pair of dibasic amino acid residues at the cleavage site, which might be a marker of highly pathogenic avian influenza virus. However, the intravenous pathogenicity index of the isolate was 0.89, indicating that the virus was approaching high pathogenicity in chickens. Virus isolation was negative in 2916 birds from 146 farms in a 3-km radius around the farm where the virus was isolated. Genetic analysis of the eight segments of the isolate indicated that the isolated virus was a reassortant whose HA and NA gene segments belonged to the American lineage and internal genes to the Eurasian lineage.

Multiple lineages of Brazilian strains from 2007 to 2008 of avian infectious bronchitis virus (IBV) were detected in flocks of breeders, broilers, and layers. Organs samples from 20 IBV-positive flocks with variable clinical signs were submitted to the partial amplification of S gene (nucleotides 726-1071) of IBV. Fifteen of the 20 sequenced strains segregated in a unique Brazilian cluster subdivided in three subclusters (Brazil 01, 02, and 03). Whereas three strains could be classified as Massachusetts (Mass) genotype, the remaining two strains, originating from flocks with reproductive and respiratory disorders, grouped within the 4/91-793B genotype, a genotype that has not been detected before in Brazil. The potential relevance of the findings to the poultry industry is discussed because the low level of identity of the sequenced part of the S gene from 17 of 20 detected field strains and the vaccines of the Massachusetts serotype used suggest that the level of cross-protection by the Massachusetts vaccines might be low.

The genetic diversity of the pvpA gene of Mycoplasma gallisepticum (MG) samples originating from commercial chickens was investigated. In the present study, we evaluated the genetic variability of 26 field samples of MG detected in commercial chickens and turkeys from 18 regions of Russia and compared them to the reference strains of MG available in GenBank. Genetic variability was evaluated by partial nucleotide sequencing of the pvpA gene, which encodes a putative cytadhesin protein. Comparisons with MG strains and isolates from the United States, Australia, China, and Iran using sequence analysis of PCR products showed that Russian MG field samples clustered more closely to each other than to the international reference MG strains. The MG pvpA sequences were found to be highly variable with a discrimination index of 0.975 for Russian field samples. No apparent cluster was found using the criteria of year or location of detection. DNA sequence polymorphism and size variation in the pvpA gene were shown among the Russian MG field samples and could be used for MG typing. These findings might help better understand the relationship among MG isolates from Russia and other countries.

By adapting a very virulent fowl adenovirus serotype 4 (FAdV-4) to a fibroblast cell line (QT35) instead of growing the virus in chicken embryo liver cells or chicken kidney cells, it was possible to attenuate the virus. Birds infected with the attenuated virus (FAdV-4/QT35) on the first day of life expressed no adverse clinical signs and no mortality. Intramuscular challenge with the virulent virus grown on chicken embryo liver cells (FAdV-4/CEL) at 21 days of life induced high mortality in previously nonvaccinated birds, whereas none of the birds vaccinated at 1 day old with FAdV-4/QT35 died due to this challenge. Applying enzyme-linked immunosorbent assay and virus neutralization assay, only a weak antibody response could be detected in some birds following vaccination, a response that increased directly after challenge. Nonvaccinated birds displayed a delayed development of antibodies after challenge as compared to previously vaccinated birds. Even birds that did not develop a measurable neutralizing antibody titer prior to challenge were protected from the adverse effects of the virulent FAdV-4/CEL, a phenomenon not described so far for FAdVs. Altogether, the present investigation underlines that neutralizing antibodies are not needed to protect chickens against a severe infection with a virulent fowl adenovirus.

The poultry meat trade in Egypt depends mainly on live bird markets (LBMs) because of insufficient slaughterhouses, lack of marketing infrastructure, and cultural preference for consumption of freshly slaughtered poultry. There are two types of LBMs in Egypt: retail shops and traditional LBMs where minimal, if any, food safety standards or veterinary inspection are implemented. Before January 2009, LBMs were considered to be a missing link in the epidemiology of avian influenza in Egypt. This incited us to initiate this surveillance to better understand the perpetuation of H5N1 and the risk of infection in poultry markets. Seventy-one out of 573 (12.4%) examined LBMs were positive for the H5N1 subtype by real-time–quantitative polymerase chain reaction (RT-qPCR) from January to April 2009. Where a 70.4% detection rate from LBMs had waterfowl only as a solitary sold species, a 26.8% detection rate from LBMs had waterfowl mixed with chicken and/or turkey, and 2.8% from LBMs had only turkey. Higher incidence, 40.8%, of positive LBMs was recorded during the cold month of February and concentrated mainly in the highly populated Nile Delta. These findings revealed wide circulation of H5N1 avian influenza virus in LBMs in Egypt, which poses a threat to public health and the poultry industry. Long-term control measures are required, and routine surveillance of bird markets should be conducted year-round.

The glycoprotein (G) gene sequences of avian metapneumovirus (aMPV) subtypes A, B, C, and D are variable in size and number of nucleotides. The G gene of early U.S. turkey isolates of aMPV-C have been reported to be 1798 nucleotides (nt) (585 aa) in length, whereas the G genes of more recent turkey isolates have been reported to be 783 nucleotides. In some studies, the G gene of aMPV-C turkey isolates was found to be truncated to a smaller G gene of 783 nt (261 aa) upon serial passages in Vero cells. This is believed to be due to the deletion of 1015 nt near the end of the open reading frame. The purpose of this study was to determine variation, if any, in the G gene of an aMPV-C isolated from a wild bird (Canada goose [Branta canadensis]) following serial passages in Vero cells. No size variation was observed for up to 50 passages, except for a few amino acid changes in the extracellular domain at the 50th passage level. The G gene of this wild bird isolate appears to be unique from subtype C metapneumoviruses of turkeys.

Infectious bursal disease virus (IBDV) is resistant to many environmental stresses and often persists on farms for months. This study investigated survival of a vaccine strain of IBDV in the bursa of Fabricius and splenic tissue from experimentally infected chickens and in splenic tissue and manure that had been inoculated with the virus. The specimens buried in compost were contained within nylon mesh bags, and the tissues were enclosed within the abdominal cavity of chicken carcasses. Extracts of composted specimens were inoculated into Vero cell cultures, and real-time reverse transcriptase PCR was used to quantify the virus in the cultures. By day 7 in compost, the temperature had been slightly above 55 C for 2.6 days and IBDV had been inactivated in specimens that had been inoculated with virus but had survived in tissues that had been taken from infected chickens. By day 14, the temperature had been above 55 C for 8.8 days and the virus was inactivated in all specimens. The results suggest that composting of poultry carcasses and manure would help to break the cycle of infection with IBDV and that the virus could be valuable as a surrogate for predicting the inactivation of less resistant viruses during composting.

The complete genome sequence of an avian paramyxovirus serotype 1 (APMV-1) isolated from a black-headed gull (Larus ridibundus) in Sweden was determined and compared with other APMV-1 sequences. Sequence analyses showed that this isolate consists of six genes in the order 3′-NP-P-M-F-HN-L-5′, is 15,186 nucleotides long, and contains a typical, avirulent fusion protein cleavage site. It was also shown to have a hemagglutinin-neuraminidase protein with a length of 585 amino acids (aa) instead of the expected 616 aa. Phylogenetic analyses showed that the isolate belongs to genotype I, and the relationship with some other, known APMV-1 virus sequences was revealed. Waterfowl have been considered to act as a reservoir for APMV-1 and, therefore, it is important to broaden the knowledge of viruses circulating within this population.

Three studies were conducted using Clostridium perfringens as an intestinal challenge to produce necrotic enteritis (NE). The studies consisted of two battery screening studies and one production study in floor pens, which were used to test the effect of the addition of Bacillus licheniformis (DSM 17236) spores at different doses and feeding periods in comparison to birds fed diets with subtherapeutic levels of virginiamycin (15 g/ton feed). In all three studies the use of B. licheniformis (1.6 × 10⁶–8 × 10⁷ CFUs/g) or virginiamycin (15 g/ton feed) showed no difference in effect with regard to feed conversion ratio, weight gain, NE lesion score, and NE mortality. In the two battery studies, both treatments showed a significantly decreased feed conversion ratio, increased weight gain, reduced NE lesion score, and NE-reduced mortality compared to the nonmedicated C. perfringens–challenged group. In general, none of the treatments performed as well as the no-challenge group. The present data indicate that the use of B. licheniformis spores as a probiotic or direct-fed microbial could be an alternative to adding medication to the feed to overcome NE under commercial-like conditions and could therefore be of direct use in preventing antibiotic-resistant pathogens in chickens.

In this study, we investigated the activity of tiamulin fumerate against three strains of Histomonas meleagridis in vitro under different conditions. Tiamulin reduced histomonal growth of all three strains at concentrations of 20 ppm and higher. Cultures in phosphate-buffered saline-based medium were more susceptible than cultures in traditional Dwyers medium. When the cultures were inoculated with higher numbers of histomonads, the activity of tiamulin was reduced. Bacteria present in the cultures were resistant against tiamulin.

To determine the expression and distribution of tegument proteins encoded by duck enteritis virus (DEV) UL51 gene in tissues of experimentally infected ducks, for the first time, an immunoperoxidase staining method to detect UL51 protein (UL51p) in paraffin-embedded tissues is reported. A rabbit anti-UL51 polyclonal serum, raised against a recombinant 6-His-UL51 fusion protein expressed in Escherichia coli, was prepared, purified, and used as primary antibodies. Fifty-eight 30-day-old DEV-free ducks were intramuscularly inoculated with the pathogenic DEV CHv strain as infection group, and two ducks were selected as preinfection group. The tissues were collected at sequential time points between 2 and 480 hr postinoculation (PI) and prepared for immunoperoxidase staining. DEV UL51p was first found in the spleen and liver at 8 hr PI; in the bursa of Fabricius and thymus at 12 hr PI; in the Harders glands, esophagus, small intestine (including the duodenum, jejunum, and ileum), and large intestine (including the caecum and rectum) at 24 hr PI; in the glandularis ventriculus at 48 hr PI; and in the pancreas, cerebrum, kidney, lung, and myocardium at 72 hr PI. Throughout the infection process, the UL51p was not seen in the muscle. Furthermore, the intensity of positive staining of DEV UL51p antigen in various tissues increased sharply from 8 to 96 hr PI, peaked during 120–144 hr PI, and then decreased steadily from 216 to 480 hr PI, suggesting that the expressional levels of DEV UL51p in systemic organs have a close correlation with the progression of duck virus enteritis (DVE) disease. A number of DEV UL51p was distributed in the bursa of Fabricius, thymus, spleen, liver, esophagus, small intestine, and large intestine of DEV-infected ducks, whereas less DEV UL51p was distributed in the Harders glands, glandularis ventriculus, cerebrum, kidney, lung, pancreas, and myocardium of DEV-infected ducks. Moreover, DEV UL51p can be expressed in the cytoplasm of various types of cells, especially most abundantly in the cytoplasm of lymphocytes, reticulum cells, macrophages, epithelial cells, and hepatocytes. The present study may be useful not only for describing the characteristics of UL51p expression and distribution in vivo but also for a greater understanding of the pathogenesis of this DVE.

Fresh ceca samples from turkeys in North Carolina infected with Histomonas meleagridis were collected at necropsy, inoculated into warmed Dwyers medium, and sent by overnight courier to our laboratory at The University of Georgia. Further incubation at 40 C yielded positive cultures from all four samples. PCR and DNA sequencing confirmed the presence of H. meleagridis. To further establish conditions for survival in transit, we infected turkeys with H. meleagridis, euthanatized the birds 10 days postinfection, and allowed carcasses to incubate at room temperature for either 2 or 24 hr. After incubation, samples of cecal contents (0.5 g) were placed in Dwyers medium and held at 4, 25, or 30 C for 6, 18, 24, 48, 72, 96, or 120 hr, simulating holding conditions during transit. Samples were placed in a 40 C incubator at the specified times and examined daily for histomonad growth by light microscopy. Positive histomonad growth was detected from cecal samples obtained from the 2-hr incubated carcass and from cultures held at 30 C for 6, 18, 24, 48, and 72 hr. No growth was seen from cultures held at 25 or 4 C or at any temperature from the carcass allowed to incubate for 24 hr at room temperature. These results suggest that positive isolation can be made from field samples, provided that material is collected at warm temperatures and transported rapidly to the laboratory.

Rhabdomyosarcoma is a malignant tumor originating from rhabdomyoblasts that is rarely reported in domestic animals or in free-living and pet birds. This paper presents a case of rhabdomyosarcoma in a free-ranging yellow-headed caracara (Milvago chimachima), originating from the muscle region of proximal left humerus, with metastases in the left pectoral muscles, heart, lungs, and proventriculus. The cytology was suggestive of rhabdomyosarcoma because of malignant features and cytoplasmic cross-striations in cells. The histopathologic examination revealed neoplastic proliferation composed of spindle cells arranged in irregular sheets or bundles with marked cellular pleomorphism, moderate mitotic ratio, and multinucleated giant cells. Some neoplastic cells also presented evidence of scant cytoplasmic cross-striations visible at histologic sections stained by hematoxylin and eosin and phosphotungstic acid hematoxylin. Immunohistochemically, tumors cells were positive for desmin and negative for α-smooth muscle actin and S100 protein.

Two diseased flamingos (Phoenicopterus roseus) with nodular lesions (pock) characteristic of poxvirus infection were found in a zoo in Japan. Avian poxvirus was isolated from the lesions (upper beak) of the affected birds and was genetically characterized by polymerase chain reaction, nucleotide sequencing, and phylogenetic analysis. Based on the phylogenetic analysis, the virus isolated from these flamingos was genetically close to those isolated from pigeons, suggesting the possibility of interspecies transmission.

A 12-year-old male pigeon (Columba livia) was reported to have a small lesion on the lower beak, which was diagnosed as malignant melanoma. After surgery to remove it, the general condition of the bird worsened and the bird died. Post mortem examination revealed gross, black-colored lesions in the liver, kidney, spleen, and femur bone marrow. Lesions were not found in the adrenals. Histopathologically, the neoplastic cells had a large amount of melanin pigment and showed severe anisokaryosis and prominent nucleoli. Mitotic activity was infrequent but varied considerably where it was observed.

Eggshell abnormalities were seen in the apex of eggs in two of three flocks of multi-age, Hy-Line layer chickens housed on a farm in Northern Italy. Approximately 1.3% to 1.8% of eggs in one flock were affected, amounting to 300–400 eggs per day; the abnormalities resulted in a great deal of breakage and spoilage of healthy eggs. The mean weight of eggs was also reduced. Egg abnormalities in a second flock were less severe. Mycoplasma synoviae was detected in birds from both of the affected flocks by serologic, cultural, and molecular techniques, but not in a third, adjacent flock where no eggshell abnormalities were seen. Treatment with tylosin, administered in the drinking water for 5 days, resulted in an immediate improvement of eggshell quality and egg weight. There was no evidence of infectious bronchitis virus in the flocks.

A young, female black-eared kite was rescued from a small reservoir adjacent to a rice paddy in Nagano Prefecture, Japan. The bird was given a fluid diet through the esophagus and started to eat by herself from the fifth day. Her fecal samples were examined for parasites on the seventh day and fluke eggs were detected. Capillaria and Ascarididae eggs were also detected from day 19 and day 32, respectively. The bird started to show loss of appetite from day 22 and finally showed no appetite on day 35. On day 38, the bird was treated with Profender Spot (Bayer Health Care, Tokyo, Japan) but died on day 41. A necropsy revealed a thickened air sac associated with considerable fungal growth. Histopathologic examination showed that the mucous membrane of the saccobronchus was thickened with hyphal proliferation, and the fungus was identified as Aspergillus fumigatus. A number of trematodes, thin nematodes, and four roundworms were obtained from the alimentary tract. Parasitologically, they were identified as Neodiplotomum pseudattenuatum, a Capillaria sp., and Porrocaecum phalacrocoracis, respectively. In conclusion, the bird was diagnosed as having fungal airsacculitis associated with multiple helminth infestations.

A commercial duck company that raises approximately two million Pekin ducks per year experienced an outbreak of Riemerella anatipestifer (RA) on nine farms over a 1-yr period. Owing to concerns that the bacteria was being spread from farm to farm, an investigation using serotyping and DNA fingerprinting was performed. The results revealed that there were three different strains of RA involved in the outbreak. One strain was spread from one farm to six other farms, while another strain from the same farm was spread to two other farms. These findings add additional proof of the value of DNA fingerprinting in disease outbreak investigations and further support the importance of implementing biosecurity protocols to stop the spread of disease-causing organisms.