Infected Flocks Research Articles

A Retrospective Study of Salmonella Enteritidis Isolated from Commercial Layer Flocks.

Consumption of shell eggs has been associated with Salmonella Enteritidis (SE) infections in humans in the United States. Because of this, the Pennsylvania Egg Quality Assurance Program (PEQAP) was developed and implemented in 1994. The PEQAP involves periodic flock testing and management practices to minimize SE contamination of shell eggs. Subsequently, the U.S. Food and Drug Administration (FDA) introduced a mandatory federal program in 2010 and 2012 for shell egg producers modeled closely after PEQAP to reduce the incidence and prevalence of SE during production, storage, and transport nationwide. In this study, a retrospective epidemiologic analysis was conducted by characterizing SE isolated from commercial layer environment samples and shell eggs submitted to the Animal Diagnostic Laboratory at The Pennsylvania State University using phage typing and pulsed-field gel electrophoresis (PFGE). The objective of this study was to determine the relatedness of SE isolates from hen house environments and shell eggs and to optimize the existing protocols of egg quality assurance programs by identifying the best layer-house environmental sampling time points in order to minimize SE contamination of shell eggs. A total of 94 SE isolates from 65 hen flocks on 35 premises in Pennsylvania recovered during 2007 to 2015 were used in this study. The SE phage type 8 and PFGE fingerprint type JEGX01.0004 most commonly associated with human SE infection was also the predominant type present in layer-house environments and shell eggs. This reconfirms hen house environmental monitoring is an effective method to identify SE-infected flocks. Further, the PEQAP program allowed SE detection of infected flocks earlier than the FDA program as it included an additional environmental test at 29-31 wk of age, enabling the earlier prevention of SE-contaminated shell eggs going to the market. Therefore, it is recommended to refine the sampling time points of the current FDA Egg Rule by adding hen house environmental testing at 29-31 wk of age.

Coxiella burnetii Circulation in a Naturally Infected Flock of Sheep: Individual Follow-Up of Antibodies in Serum and Milk.

The control of Q fever, a zoonotic disease caused by the Coxiella burnetii bacterium, remains a scientific challenge. Domestic ruminants are considered the main reservoir, shedding C. burnetii essentially through parturition products during abortion or birth. Sheep are particularly frequently associated with human outbreaks, but there are insufficient field data to fully understand disease dynamics and to instigate efficient control measures. A longitudinal follow-up study of a naturally infected sheep flock was performed (i) to investigate relationships between seropositivity and bacterial shedding in the vaginal mucus, (ii) to describe the kinetics of antibodies, including responses to vaccination, (iii) to monitor maternal antibodies in ewe lambs, and (iv) to compare serological results for milk and serum samples. For 8 months, we collected blood samples every 3 weeks from 11 aborting and 26 nonaborting dairy ewes, 20 nonaborting suckler ewes, and 9 ewe lambs. Individual milk samples were also obtained from lactating females. All serum and milk samples were tested by enzyme-linked immunosorbent assay (ELISA), whereas vaginal swabs were tested by quantitative PCR. We found that some dairy females did not seroconvert despite shedding C. burnetii in their vaginal mucus. Overall, antibody levels in adult females were found to remain stable over time, with exceptions during the mating and lambing periods. Maternal antibodies decreased during the first month after birth. Interestingly, antibody levels in milk were correlated with those in serum. This study provides valuable field data that will help improve Q fever surveillance and within-flock management measures.IMPORTANCE Field data are necessary to improve the surveillance, diagnosis, and sanitary management of Q fever in livestock. Here, we provide extensive serological data obtained from serum and milk samples from infected and vaccinated ewes belonging to a naturally infected flock of sheep. We show that antibody levels are stable over time and seropositivity and vaginal shedding are not clearly correlated, whereas antibody levels in milk are strongly correlated with those in serum. Accordingly, we find that antibody levels in bulk tank milk are consistent with the variations observed in the serum of dairy females over time. We report the existence of maternal antibody transmission to ewe lambs and we show that the presence of maternal antibodies at birth does not prevent the development of a serological response to vaccination at the age of 4 months. Finally, we report that adult ewes generally seroconvert after vaccination, including during pregnancy.

Isolation and identification of the Newcastle disease virus from field outbreaks in broiler and layer flocks in Iraq

Newcastle disease is one of serious pathological problems and causes of vast economic losses during 2011-2016 in Iraq. The disease caused high mortalities in all types of poultry nevertheless of vaccination. In this study all samples were collected from infected flocks with clinical signs of the disease. Inoculation of chicken embryonated eggs was carried out for virus isolation, identification, Haemagglutination and Haemagglutination Inhibition assay. Using Reverse Transcriptase-Polymerase Chain Reaction to confirm the presence of the virus, Intra Cerebral Pathogenicity Index and Mean Death Time were used to confirm all the isolates that were velogenic. The important determinant of Newcastle disease virus pathogenicity is fusion protein that has been used for phylogenetic analysis. sequencing and compared genetically of Newcastle disease virus Iraqi isolate to publish sequences acquired from GenBank showed 99% sequence similarity to the Iran isolate IRI 1392k (KJ176996.1). It can concluded from these data that introduction new virus was occurred in Iraq.

Prevalence of Coxiella burnetii in cows’ and ewes’ bulk tank milk samples from selected dairy farms of Central Italy

The prevalence of Coxiella burnetii, the causative agent of Q fever, in cattle and sheep raw milk farms was determined in Central Italy, an area in which dairy production plays an important economic role. Milk samples (n. 189), collected from 66 dairy farms in 2012–2013, were tested by a commercial real-time PCR assay. Seventeen dairy farms had at least one positive milk sample; percent positive was higher for cattle (50%) than sheep (21%) farms. Concerning milk, 15% of samples tested overall gave a positive result, with the highest percentage of positivity observed for bovine milk compared with sheep milk (41% and 12%, respectively). In the only bovine farm repeatedly sampled during the study, C. burnetii contamination was persistently found for almost a year. The prevalence calculated for the sheep farms showed a discontinuous trend with a maximum peak in February. The results obtained underline the widespread presence of the pathogen in the considered geographical area, giving new epidemiological information. Since the milk route of elimination is a potential vehicle of infection for farmers, veterinarians and for dairy stakeholders in general, BTM screening by real-time PCR can be applied as a useful surveillance tool both for the identification of infected flocks and implementation of control programmes.

Primary Newcastle disease vaccination of broilers: comparison of the antibody seroresponse and adverse vaccinal reaction after eye–nose drop or coarse spray application, and implication of the results for a previously developed coarse dry powder vaccine

ABSTRACTTo compare antibody seroresponse and adverse vaccinal reaction induced by Newcastle disease (ND) vaccination after eye–nose drop or coarse spray, groups of SPF broiler hens were vaccinated at day 4 (day of hatch is day 0) and intratracheally inoculated with Escherichia coli at day 11. Body weight gain (BWG) was assessed between day 4 and day 18; colibacillosis lesions and serum antibodies were determined at day 18. Meaningful comparison requires similar vaccine uptake. Vaccine virus loss during spray relative to eye–nose drop, which was assessed by comparing the results of endpoint titrations, was 3 log10. Colibacillosis lesions in birds spray vaccinated with 106.4 EID50/chicken were significantly more severe (P < 0.05), compared to those in birds eye–nose drop vaccinated with 103.4 EID50/chicken, while the seroresponse was slightly but significantly (P < 0.05) stronger. Colibacillosis lesion scores inversely paralleled BWG. It is concluded that: (1) There is room to improve the coarse ND vaccine spray used regarding adverse vaccinal reaction, while maintaining a sufficient immune response. This is also applicable to the coarse ND powder vaccine studied in previous research, which induced similar antibody response and adverse vaccinal reaction as the spray vaccine used here. (2) The vaccine virus dose influences the colibacillosis susceptibility at seven days post vaccination, as the dynamics of the vaccine virus infection is likely dose-dependent. (3) Low vaccine virus doses likely result in heterogeneous vaccine-take followed by vaccine virus spread from vaccine shedding birds to their non-vaccine virus infected flock mates (“rolling vaccinal reaction”).

A novel avian retrovirus associated with lymphocytoma isolated from a local Chinese flock induced significantly reduced growth and immune suppression in SPF chickens

Avian Leukosis Viruses (ALVs) are associated with neoplasias, immune suppression and reduced performance in chicken flocks. In the present study, a naturally occurring recombinant strain of ALV (FJ15HT0) was isolated from an infected flock of Chinese “Hetian” chickens, and was subsequently identified as an exogenous ALV by immuno-fluorescence assay (IFA), PCR and following entire proviral DNA nucleotide sequencing. This isolate is revealed as a novel recombinant virus, lacking viral oncogenes, with the gp85 (93.4%) of subgroup B, the U3 (92.1%) and R (95.2%) region of subgroup J, the U5 (93.8%) region and 5′UTR (95.7%) of subgroup C, as well as the gp37 (90.6%) and 3′ (92.2%) of ALV-E. The simulative congenital infection with this isolate in SPF chickens resulted in significant weight loss (P<0.05) and a significant reduction in the humoral immune response to the live NDV vaccine (P<0.05), but not to the inactive AIV-H5 vaccine (P>0.05). Foci of lymphocytomas were observed in tissues of congenitally infected chickens at 11 weeks post-hatch, demonstrating the acute oncogenicity of the isolate.

Muscovy duck reovirus \u03c3NS protein triggers autophagy enhancing virus replication

BackgroundMuscovy duck reovirus (MDRV) causes high morbidity and mortality in Muscovy ducklings at 10 days old and can persist in an infected flock until the ducklings of 6 weeks old. It shares common physicochemical properties with avian reovirus (ARV) and differs in coding assignment and pathogenicity. The ARV p17 protein has been shown to trigger autophagy via activation multiple signaling pathways, which benefits virus replication. Since MDRV lacks the p17 protein, whether and how MDRV induces autophagy remains unknown. The aim of this study was to explore whether MDRV induces autophagy and which viral proteins are involved in MDRV-induced autophagy.MethodsThe autophagosome-like structures in MDRV-infected cells was observed under transmission electron microscopy. MDRV-induced autophagy was examined by analyzing the LC3-II level and phosphorylated form of mammalian target of rapamycin (mTOR) by Western blot assays. The effects of 3-methyladenine, rapamycin, chloroquine on viral yields were measured with quantitative(q) real-time reverse transcription (RT)-polymerase chain reaction (PCR) and 50% tissue culture infective dose (TCID50) assays, respectively. Additionally, to determine which viral protein is responsible for MDRV-induced autophagy, both p10.8- and σNS-encoding genes of MDRV were cloned into the pCI-neo-flag vector and transfected into DF-1 cells for detection of LC3-II.ResultsThe typical double-membrane vesicles containing cytoplasmic inclusions were visible in MDRV-infected immortalized chicken embryo fibroblast (DF-1) cells under transmission electron microscopy. Both primary Muscovy duck embryo fibroblasts (MDEF) and DF-1 cells infected with MDRV exhibited a significant increased levels of LC3-II accompanied with downregulation of phosphorylated form of mTOR, further confirming that MDRV is capable of inducing autophagy. Autophagy could be suppressed by 3-methylademine and induced by rapamycin and chloroquine. Furthermore, we found that σNS induces an increased levels of LC3-II, suggesting that the MDRV σNS protein is one of viral proteins involved in induction of autophagy. Both qRT-PCR and TCID50 assays showed that virus yield was increased in rapamycin treated DF-1 cells following MDRV infection. Conversely, when infected cells were pretreated with chloroquine, virus yield was decreased.ConclusionsThe MDRV σNS nonstructural protein is responsible for MDRV-induced autophagy and benefits virus replication.

Three Cases ofEscherichia coliMeningitis in Chicks Imported to Japan

Three outbreaks of colibacillosis have occurred in chicks during the quarantine period after importation to Japan. All three were derived from three different countries without epidemiologic relevance. Some birds from each infected flock were examined pathologically and bacteriologically. The characteristic histologic finding common to all three cases was severe bacterial meningitis in the central nervous system. Pericarditis, perihepatitis, and omphalitis with bacterial colonies were also observed. The bacterial colonies observed histologically were immunohistochemically positive for Escherichia coli antigens. Escherichia coli was isolated from the organ samples from each outbreak. At least two E. coli isolates were serotyped as O18 and O161, which differed from the popular serotypes in Japan. These results suggest that avian pathogenic E. coli of uncommon serotypes can be imported from outside countries by infected chicks. Colibacillosis should be included in the differential diagnosis when meningitis is histologically observed in chicks.

Molecular Characterization of Hemorrhagic Enteritis Viruses (HEV) Detected in HEV-Vaccinated Commercial Turkey Flocks in Germany

Despite the application of live hemorrhagic enteritis virus (HEV) vaccines, HEV field outbreaks are suspected to still occur in turkey flocks in Germany. Increasing secondary bacterial infections in HEV-vaccinated flocks suggest that vaccines may be losing efficacy or, possibly, that vaccine strains are causing disease. Thus, the goal of the current study was to investigate the diversity of HEV isolates from fattening turkey flocks between 2008 and 2012 by characterizing the open reading frame (ORF)1 gene at its 5' and 3' ends. Analyses of ORF1 sequences of field isolates and comparison with sequences present in databases revealed that in many cases (13 out of 16 samples), vaccine (avirulent) strains were present. In addition, data indicated the circulation of suspected virulent field isolates and these isolates (3 out of 16) cluster with an early isolate from Germany in the 1980s, but show some mutations in the predicted amino acid (aa) sequences of ORF1 compared to the early isolate. These virulent isolates clearly differ from the spleen-derived avirulent Domermuth vaccine strain used in Germany. In this study, a unique isolate was identified and showed unusual nucleotide mutations that resulted in aa exchanges at the 5' end of ORF1 between aa positions 34 and 174. This genetic drift suggests evolution of HEV including virulent and vaccine-derived strains in the field. This may lead to evasion of vaccinal immunity by drifted viruses and/or an increase in the virulence of field strains.

Occurrence of Salmonella spp.: a comparison between indoor and outdoor housing of broilers and laying hens

BackgroundOutdoor production of poultry is rapidly increasing, which could be associated with increased risks for exposure to different environmental sources of Salmonella. We report a comparison on the occurrence of Salmonella during 2007–2015 in broilers and laying hens in outdoor and indoor production subjected to the same requirements for the prevention and control of Salmonella as applied in Sweden.ResultsOur results give no indication that, during the period studied, the exposure to Salmonella in outdoor poultry production was higher than in the indoor production. The annual incidence of Salmonella infected flocks in outdoor production remained at a very low and at a similar level as for indoor production. For laying hens the annual proportion of birds in test positive flocks ranged from 0 to 1.3% for indoor production from 0 to 2.0% for outdoor production. For broilers the proportion of Salmonella infected flocks (2013–2015) was 0.16% for indoor, and 0% in outdoor production. The difference was not statistically significant and was further reduced when flocks infected due to vertical transmission or from a hatchery source were excluded. It should, however, be considered that the number of outdoor flocks included in this evaluation is very small and continuous evaluation is needed.ConclusionsNew animal production systems, including those driven by consumer and welfare demands, may be associated with a higher risk for the exposure of potential pathogens to food animals and possibly also subsequent outbreaks of food borne infections. In this study no increase in the risk for exposure of flocks to Salmonella in outdoor poultry production was found. The situation may well change and the possibility of Salmonella contamination in outdoor poultry production requires continuous attention.

A novel hemagglutinin protein produced in bacteria protects chickens against H5N1 highly pathogenic avian influenza viruses by inducing H5 subtype-specific neutralizing antibodies.

The highly pathogenic (HP) H5N1 avian influenza viruses (AIVs) cause a mortality rate of up to 100% in infected chickens and pose a permanent pandemic threat. Attempts to obtain effective vaccines against H5N1 HPAIVs have focused on hemagglutinin (HA), an immunodominant viral antigen capable of eliciting neutralizing antibodies. The vast majority of vaccine projects have been performed using eukaryotic expression systems. In contrast, we used a bacterial expression system to produce vaccine HA protein (bacterial HA) according to our own design. The HA protein with the sequence of the H5N1 HPAIV strain was efficiently expressed in Escherichia coli, recovered in the form of inclusion bodies and refolded by dilution between two chromatographic purification steps. Antigenicity studies showed that the resulting antigen, referred to as rH5-E. coli, preserves conformational epitopes targeted by antibodies specific for H5-subtype HAs, inhibiting hemagglutination and/or neutralizing influenza viruses in vitro. The proper conformation of this protein and its ability to form functional oligomers were confirmed by a hemagglutination test. Consistent with the biochemical characteristics, prime-boost immunizations with adjuvanted rH5-E. coli protected 100% and 70% of specific pathogen-free, layer-type chickens against challenge with homologous and heterologous H5N1 HPAIVs, respectively. The observed protection was related to the positivity in the FluAC H5 test (IDVet) but not to hemagglutination-inhibiting antibody titers. Due to full protection, the effective contact transmission of the homologous challenge virus did not occur. Survivors from both challenges did not or only transiently shed the viruses, as established by viral RNA detection in oropharyngeal and cloacal swabs. Our results demonstrate that vaccination with rH5-E. coli could confer control of H5N1 HPAIV infection and transmission rates in chicken flocks, accompanied by reduced virus shedding. Moreover, the role of H5 subtype-specific neutralizing antibodies in anti-influenza immunity and a novel correlate of protection are indicated.

Evaluation of the presence of avian influenza receptors in oviducts of forced moulting birds using immunofluorescence

During the 2012 highly pathogenic avian influenza outbreak in Mexico caused by the H7N3 subtype, infection led to the death of approximately 22 million laying hens. Thus, poultry farmers were faced with a challenge to ensure the continued commercial flow of eggs. In addition to implementing established sanitary protocols and vaccination programs, forced moulting management was utilized in the affected areas. This strategy guaranteed the maintenance of egg production in the quarantined areas by decreasing the mortality of the infected flock while re-stimulating egg production. To understand how forced moulting reduced mortality of the infected birds, we examined the distribution of the avian influenza receptor in the oviduct of hens subjected to forced moulting. We tested if changes in the reproductive tract caused by forced moulting generated a decrease in the expression of the specific virus receptor in the cell membranes. Host susceptibility to the influenza virus was determined by the presence of these specific receptors. We utilized immunofluorescence of the Maackia amurensis lectin to identify the presence of the virus receptor in histological sections of the oviducts of birds in egg production and birds undergoing forced moulting. The results showed the presence and distribution of the receptors for avian influenza. A strong signal of the receptor was observed in the histological sections of the oviducts of birds in egg production. Conversely, the signal was low in the oviducts of birds undergoing forced moulting. These results demonstrate a decrease in the number of receptors of birds subjected to forced moulting. A lack of receptors would affect virus infection and replication as well as virus-induced damage in the oviduct, which may help explain the observation in the field that birds infected with avian influenza and subjected to forced moulting have decreased mortality.A. Abundant amount of influenza-like receptors, labelled with apple-green fluorescence, on the apical region of the ciliated cylindrical pseudostratifiedepithelium of the uterine region of healthy hens in production. Bar: 100 μm.

Wild Birds, a Source of Reticuloendotheliosis Virus Infection for the Endangered Attwater's Prairie-Chicken ( Tympanuchus cupido attwateri)?

Reticuloendotheliosis virus (REV) infects a wide range of avian species. Since 1998, when it was first reported in a captive flock of the endangered Attwater's Prairie-chicken ( Tympanuchus cupido attwateri; APC), REV has plagued APC recovery efforts. While REV frequently occurs in captive bird flocks throughout the world, including commercial poultry, the reservoir for initial infection of flocks is poorly understood. From 2008-16, 412 blood samples and 216 liver samples collected from 32 species of birds on or near Attwater Prairie Chicken National Wildlife Refuge in Colorado County, Texas, US, and 89 blood samples obtained from a Texas game farm that provides thousands of Northern Bobwhites ( Colinus virginianus ) and Ring-necked Pheasants ( Phasianus colchicus ) for hunting throughout Texas, were tested for REV by real-time PCR. Of the 717 samples, one liver sample from a Savannah Sparrow ( Passerculus sandwichensis ) and three blood samples from game farm Ring-necked Pheasants tested positive for REV. These data, although limited, indicate a low prevalence of REV in birds sharing or in close proximity to APC habitat. More-extensive surveillance testing is warranted to determine the spatial and temporal dynamics of REV in wild bird populations and the relative role these birds may play as potential reservoirs for maintaining REV infections in both the wild and captive setting.

Application of pigeon circovirus recombinant capsid protein for detecting anti-PiCV antibodies in the sera of asymptomatic domestic pigeons and the potential use of a combination of serological and molecular tests for controlling circovirus infections in pigeon breeding flocks

The aim of this study was to evaluate the serologic status of domestic pigeons not infected and asymptomatically infected with the pigeon circovirus (PiCV) with the use of an enzyme-linked assay based on PiCV recombinant capsid protein as a plate antigen. Recombinant PiCV capsid protein was produced by transforming E. coli BL21 (DE3) Rosetta colonies with expression plasmids.Blood samples and cloacal swabs were collected from 171 asymptomatic pigeons. The birds were divided into two groups (infected and not infected with PiCV) based on the results of Sybr Green real time PCR screening for the presence of PiCV genetic material. Approximately 70% of the pigeons tested positive for anti-PiCV antibodies regardless of their infection status. Antibody levels, the coefficient of variation and standard deviation were significantly higher in the group of infected pigeons.The results indicate that ELISA is a highly useful test that complements molecular methods in evaluations of PiCV infection status in domestic pigeons. The spread of pigeon circovirus infections can be controlled by keeping breeding flocks free of PiCV, which can only be achieved by subjecting birds to real time PCR and serological tests.

Update on Epidemiology, Diagnosis and Control Technique of Newcastle Disease

Newcastle disease is an acute, contagious viral disease of birds. It is one of the most important diseases which cause great economic loss in poultry industry. The virus that cause Newcastle disease is grouped under family Paramyxoviridae in the genus Avulavirus and species avian paramyxovirus type 1 (APMV-1) or Newcastle disease virus. Based on their virulence Newcastle disease virus can be divided in to viscerotropic, neurotropic, mesogenic and lentogenic strain. Although avian paramyxovirus type 1(APMV-1) can affect many species of birds including wild birds, Chickens are highly susceptible to the disease. The objectives of this paper were to highlight the epidemiology, diagnostic technique and control measures involved in Newcastle disease. Newcastle disease is currently distributed throughout the world including Central and South America, Asia, Middle East and Africa. APMV-1 can be transmitted by inhalation or ingestion, and birds shed these viruses in both feces and respiratory secretions. The virus can also be transmitted through direct contact with infected flock and indirect contact with contaminated materials. This disease can be diagnosed based history of disease outbreak, some pathognomic sign and laboratory test such as virus isolation, serological test and molecular technique. The latter has more important being its sensitive and rapid for diagnosis of the disease. Currently both live and killed vaccines are used in many countries to control and prevent the disease in chickens. Furthermore, strict biosecurity and separation infected once from health flock are also important to control and prevent spread of disease. Generally to make poultry free of this disease, good biosecurity and continual vaccination should be maintained.

Occurrence of Salmonella on poultry farms, in flocks of pigeons and feed monitored by the Department of Veterinary Hygiene in Olsztyn in the years 2014-2015

The aim of the study was to analyze the frequency of the occurrence of Salmonella and their serotypes on poultry farms, in flocks of pigeons, and feed monitored by the Department of Veterinary Hygiene in Olsztyn in the years 2014-2015. The quantitative and qualitative analysis was conducted according to the requirements of Polish Standards. On the poultry farms 0.9% samples gave positive results and in 2015 the percentage of infected farms was 0.3% lower compared to 2014. S. Enteritidis serotypes were isolated from 0.2% samples from poultry farms and S. Typhimurium from 0.08%. These two most pathogenic serotypes were isolated three times more in 2014 (in 0.41% of cases). S. Enteritidis is the most frequently observed serotype (particularly in broiler chickens) and compared with the results of the previous years (2001-2005) in the same region, the number of cases of this serotype in broiler flocks decreased markedly. Next, there were S. Lexington, S. Kentucky, S. Typhimurium and S. Mbandaka. In 2015 the intensity of the occurrence of S. Enteritidis on farms decreased, and the percentage of positive results S. Enteritidis or S. Typhimurium was the same as in the case of S. Kentucky and S. Mbandaka. In pigeon flocks all isolates belonged to S. Typhimurium, accounting for 2.4%. In the case of feed, 1.34% of positive results were found (0.3% in blends for poultry). The implementation of EU programs to reduce Salmonella contributed to a significant reduction of infected poultry flocks and feed, but at the same time there is a greater variety of serotypes of Salmonella, which on account of their antibiotics resistance may pose a risk.

Quantitative risk assessment of Campylobacter in broiler chickens – Assessing interventions to reduce the level of contamination at the end of the rearing period

The European Food Safety Authority (EFSA) has estimated that a proportion ranging from 20% to 30% of campylobacteriosis in humans may be attributed to the consumption of broiler meat and a reduction in the numbers of Campylobacter in the intestines of infected birds at slaughter by 3 log units would reduce the public health risk by at least 90%. In this study, a stochastic model was implemented to reproduce the dynamics of Campylobacter transmission in broiler flocks and explore the effects of several management conditions and/or on-farm mitigation strategies on the estimated level of contamination of infected flocks at slaughter. Results were expressed as ‘proportion of highly contaminated flocks’ (%HCFs) and estimated as a function of the proportion of infected birds in the flock the day of final depopulation and the individual level of contamination in infected birds. The effects of the mitigation strategies aimed at reducing the level of contamination in infected birds were modelled assuming that those effects are exerted on the distribution describing the bacterial load in infected birds. The impact of management conditions such as the adoption of enhanced biosecurity measures (B+) and/or partial depopulation during the production cycle (T+) were quantified using results of an extensive epidemiological study conducted in UK. A standard broiler flock was reproduced and used as baseline to make comparisons and simulate the effects of the mitigation strategies of interest. The baseline model predicted 18.8% probability of HCFs at slaughter. A positive effect ranging from −32.44% to −4.78% was attributed to B+ while T+ had negative effect ranging from +17.55% to +86.70%. When both the effects were tested simultaneously (B+T+), results were not conclusive with %HCFs ranging from −20.21% to +77.65%. When mitigation strategies operating on Campylobacter concentration in intestine were tested, a reduction of 100% and 99.6% in %HFCs were estimated following a generic treatment with bacteriocins and bacteriophages. Reduction in %HCFs as a function of immunization measures were explored and a reduction of 15% in the rate of transmission led to a %HCFs at slaughter reduced by almost 50%. The model was developed to be flexible, easily reproducible, updatable and adaptable to several baseline scenarios. The main parameters and assumptions underlying the baseline model were tested and a sensitivity analysis was performed to identify and discuss the impact that the uncertainty in the baseline information might have on the outcomes.

Pathological Studies on Infectious Bronchitis Disease in Chickens

Infectious bronchitis virus has been recognized as highly contagious disease in chickens. In this study, 138 birds from 10 broiler chicken flocks that suffered from respiratory disease were examined to study the pathological lesions associated with IBV infection in naturally infected flocks. Moreover, the infection was confirmed via virus isolation and PCR. Samples were harvested from both Sharkia and Gharbia provinces during one year. The clinical examination of the investigated birds showed nasal discharges, gasping and rales. Congested trachea with lumen contained mucus and caseated material at the biforcation of the two main bronchi were characteristic in most of the necropsied birds. The kidneys were enlarged and dark red or pale with the presence of whitish precipitate in the ureters. Four isolates recovered from four different broilers chicken’s flocks were further analyzed by S1 glycoprotein gene sequencing. The phylogenetic analysis of the deduced amino acids sequences of the four strains revealed that they were closely related to the IBV Egyptian variant 2 and IS/1494/2006 strains. The histopathological examination of the kidneys showed focal aggregation of lymphocytes in the renal cortex and the medulla. The liver showed multiple focal areas of necrosis which replaced by lymphocyte and heterophils aggregation. The spleen showed thickened capsule with subcapsular hemorrhage and mild to severe focal depletion of lymphocytes. Trachea, lung, proventriculus, intestine and bursa showed hyperplasia and degenerative changes in their epithelium. Blood vessels showed endotheliosis with perivascular edema and leukocyte infiltration in various organs. Edema was also seen in heart, trachea and lungs. Finally, it could be concluded that infectious bronchitis virus is a major cause and strongly implicated in respiratory and/or renal problems of the Egyptian broiler chicken flocks. Moreover, Egyptian variant 2 still evolving and causing severe damage to renal tissue and various organs.

Modelling the impact of co-circulating low pathogenic avian influenza viruses on epidemics of highly pathogenic avian influenza in poultry

It is well known that highly pathogenic avian influenza (HPAI) viruses emerge through mutation of precursor low pathogenic avian influenza (LPAI) viruses in domestic poultry populations. The potential for immunological cross-protection between these pathogenic variants is recognised but the epidemiological impact during co-circulation is not well understood. Here we use mathematical models to investigate whether altered flock infection parameters consequent to primary LPAI infections can impact on the spread of HPAI at the population level. First we used mechanistic models reflecting the co-circulatory dynamics of LPAI and HPAI within a single commercial poultry flock. We found that primary infections with LPAI led to HPAI prevalence being maximised under a scenario of high but partial cross-protection. We then tested the population impact in spatially-explicit simulations motivated by a major avian influenza A(H7N1) epidemic that afflicted the Italian poultry industry in 1999–2001. We found that partial cross-protection can lead to a prolongation of HPAI epidemic duration. Our findings have implications for the control of HPAI in poultry particularly for settings in which LPAI and HPAI frequently co-circulate.

Investigation into the Airborne Dissemination of H5N2 Highly Pathogenic Avian Influenza Virus During the 2015 Spring Outbreaks in the Midwestern United States.

We investigated the plausibility of aerosol transmission of H5N2 highly pathogenic avian influenza (HPAI) virus during the 2015 spring outbreaks that occurred in the U.S. midwest. Air samples were collected inside and outside of infected turkey and layer facilities. Samples were tested to assess HPAI virus concentration (RNA copies/m(3) of air), virus viability, and virus distribution by particle size. HPAI virus RNA was detected inside and up to 1000 m from infected facilities. HPAI virus was isolated from air samples collected inside, immediately outside, up to 70 m from infected facilities, and in aerosol particles larger than 2.1 μm. Direct exposure to exhausted aerosols proved to be a significant source of environmental contamination. These findings demonstrate HPAI virus aerosolization from infected flocks, and that both the transport of infectious aerosolized particles and the deposition of particles on surfaces around infected premises represent a potential risk for the spread of HPAI.