Presence Of Avian Influenza Virus Research Articles

Avian influenza viruses in New Zealand wild birds, with an emphasis on subtypes H5 and H7: Their distinctive epidemiology and genomic properties.

The rapid spread of highly pathogenic avian influenza (HPAI) A (H5N1) viruses in Southeast Asia in 2004 prompted the New Zealand Ministry for Primary Industries to expand its avian influenza surveillance in wild birds. A total of 18,693 birds were sampled between 2004 and 2020, including migratory shorebirds (in 2004-2009), other coastal species (in 2009-2010), and resident waterfowl (in 2004-2020). No avian influenza viruses (AIVs) were isolated from cloacal or oropharyngeal samples from migratory shorebirds or resident coastal species. Two samples from red knots (Calidris canutus) tested positive by influenza A RT-qPCR, but virus could not be isolated and no further characterization could be undertaken. In contrast, 6179 samples from 15,740 mallards (Anas platyrhynchos) tested positive by influenza A RT-qPCR. Of these, 344 were positive for H5 and 51 for H7. All H5 and H7 viruses detected were of low pathogenicity confirmed by a lack of multiple basic amino acids at the hemagglutinin (HA) cleavage site. Twenty H5 viruses (six different neuraminidase [NA] subtypes) and 10 H7 viruses (two different NA subtypes) were propagated and characterized genetically. From H5- or H7-negative samples that tested positive by influenza A RT-qPCR, 326 AIVs were isolated, representing 41 HA/NA combinations. The most frequently isolated subtypes were H4N6, H3N8, H3N2, and H10N3. Multivariable logistic regression analysis of the relations between the location and year of sampling, and presence of AIV in individual waterfowl showed that the AIV risk at a given location varied from year to year. The H5 and H7 isolates both formed monophyletic HA groups. The H5 viruses were most closely related to North American lineages, whereas the H7 viruses formed a sister cluster relationship with wild bird viruses of the Eurasian and Australian lineages. Bayesian analysis indicates that the H5 and H7 viruses have circulated in resident mallards in New Zealand for some time. Correspondingly, we found limited evidence of influenza viruses in the major migratory bird populations visiting New Zealand. Findings suggest a low probability of introduction of HPAI viruses via long-distance bird migration and a unique epidemiology of AIV in New Zealand.

Avian Influenza Virus and Avian Paramyxoviruses in Wild Waterfowl of the Western Coast of the Caspian Sea (2017-2020).

The flyways of many different wild waterfowl pass through the Caspian Sea region. The western coast of the middle Caspian Sea is an area with many wetlands, where wintering grounds with large concentrations of birds are located. It is known that wild waterfowl are a natural reservoir of the influenza A virus. In the mid-2000s, in the north of this region, the mass deaths of swans, gulls, and pelicans from high pathogenicity avian influenza virus (HPAIV) were noted. At present, there is still little known about the presence of avian influenza virus (AIVs) and different avian paramyxoviruses (APMVs) in the region's waterfowl bird populations. Here, we report the results of monitoring these viruses in the wild waterfowl of the western coast of the middle Caspian Sea from 2017 to 2020. Samples from 1438 individuals of 26 bird species of 7 orders were collected, from which 21 strains of AIV were isolated, amounting to a 1.46% isolation rate of the total number of samples analyzed (none of these birds exhibited external signs of disease). The following subtypes were determined and whole-genome nucleotide sequences of the isolated strains were obtained: H1N1 (n = 2), H3N8 (n = 8), H4N6 (n = 2), H7N3 (n = 2), H8N4 (n = 1), H10N5 (n = 1), and H12N5 (n = 1). No high pathogenicity influenza virus H5 subtype was detected. Phylogenetic analysis of AIV genomes did not reveal any specific pattern for viruses in the Caspian Sea region, showing that all segments belong to the Eurasian clades of classic avian-like influenza viruses. We also did not find the amino acid substitutions in the polymerase complex (PA, PB1, and PB2) that are critical for the increase in virulence or adaptation to mammals. In total, 23 hemagglutinating viruses not related to influenza A virus were also isolated, of which 15 belonged to avian paramyxoviruses. We were able to sequence 12 avian paramyxoviruses of three species, as follows: Newcastle disease virus (n = 4); Avian paramyxovirus 4 (n = 5); and Avian paramyxovirus 6 (n = 3). In the Russian Federation, the Newcastle disease virus of the VII.1.1 sub-genotype was first isolated from a wild bird (common pheasant) in the Caspian Sea region. The five avian paramyxovirus 4 isolates obtained belonged to the common clade in Genotype I, whereas phylogenetic analysis of three isolates of Avian paramyxovirus 6 showed that two isolates, isolated in 2017, belonged to Genotype I and that an isolate identified in 2020 belonged to Genotype II. The continued regular monitoring of AIVs and APMVs, the obtaining of data on the biological properties of isolated strains, and the accumulation of information on virus host species will allow for the adequate planning of epidemiological measures, suggest the most likely routes of spread of the virus, and assist in the prediction of the introduction of the viruses in the western coastal region of the middle Caspian Sea.

Determinants for the presence of avian influenza virus in live bird markets in Bangladesh: Towards an easy fix of a looming one health issue

Highly pathogenic avian influenza virus subtype H5N1 endangers poultry, wildlife, and human health and is enzootic in large parts of Asia, with live bird markets (LBMs) as putative hotspots for their maintenance, amplification, and spread. To mitigate the extent of these and other avian influenza viruses (AIV) of concern, we aimed to increase our quantitative understanding of the factors determining the presence of avian influenza virus in LBM stalls. Between 2016 and 2017, we collected fecal or offal samples from 1008 stalls in 113 LBMs across the Dhaka and Rajshahi districts in Bangladesh. For each stall, samples were pooled and tested for the AIV matrix gene, followed by H5 and H9 subtyping using rRT-PCR. We detected Influenza A viral RNA in 49% of the stalls. Of the AIV positive samples, 52% and 24% were determined to be H5 and H9 viruses, respectively, which are both subtypes of considerable health concern. We used generalized linear mixed effect modelling to study AIV presence in individual stalls within LBMs as a function of 13 out of the 20 risk factors identified by FAO. We found that small and feasible improvements in cleaning and disinfection frequency, installing running water in stalls, and not mixing different breeds of chicken in the same cages had large impacts on the presence of AIV in stalls (Odds ratios 0.03–0.05). Next, cleaning vehicles used in poultry transport, not selling waterfowl with chickens in the same stall, buying stock directly from commercial farms, separating sick birds from healthy ones, and avoiding access by wild birds like house crows, also had major effects on lowering the risk of stalls having AIV (Odds ratios 0.16–0.33). These findings can be directly used in developing practical and affordable measures to reduce the prevalence of AIV in LBMs. Also, in settings with limited resources like Bangladesh, such mitigation may significantly contribute to reducing AIV circulation amongst poultry and spillover to wildlife and humans.

An animal-friendly collection of samples from the upper respiratory tract via drinker-swabs for the detection of avian influenza (H5N1) in poultry flocks

To take tracheal swabs from poultry flocks, for detection of avian influenza viruses is time-consuming and involves a high workload for the staff and a lot of stress for the sampled animals. Therefore, an animal-friendly and at the same time reliable method of collected of samples from poultry flocks is needed. A simple method would be a significant improvement in the control of avian influenza, especially in poultry-intensive regions. Swab samples in/on drinkers can easily be taken. When taking water, every animal with a respiratory infection leaves small amounts of its respiratory secretions (mucus) in/on the drinkers. Even before the first clinical signs appear in a flock, the influenza virus is already in small amounts of mucus particle in the drinkers present. By sampling swabs in/on many drinkers in the barn these smallest amounts of respiratory murus from infected birds in the flock can be detected by PCR-technic. In contrast to the faecal samples, the samples from the drinkers contain only a small amount of DNA and RNA from microorganisms
 The PCR results from this field study allow the conclusion that swabs from the drinkers in the barn yield very reliable and very important information about the presence of avian influenza viruses in a poultry population. However, it is important to take swab samples from many drinkers in the barn. An Influenza monitoring with swab samples from drinkers is rapid, sensitive, specific, reliable, inexpensive and can be taken easily by individuals, regardless of the age and the number of birds in the flock. Detecting the avian influenza virus in infected flocks with swab sampling in/on drinkers is an animal-friendly process with an improvement in the statistical significance of the infection status of a flock.

Avian Influenza a H9N2 Viruses in Morocco, 2018-2019.

Low pathogenic H9N2 avian influenza (LPAI H9N2) is considered one of the most important diseases found in poultry (broiler, laying hens, breeding chickens, and turkeys). This infection causes considerable economic losses. The objective of this work was to monitor and assess the presence of avian influenza virus (AIV) H9N2 in eight different regions of Morocco using real-time RT-PCR, and to assess the phylogenetic and molecular evolution of the H9N2 viruses between 2016 and 2019. Field samples were collected from 108 farms suspected of being infected with LPAI H9N2 virus. Samples were analyzed using H9N2-specific real-time RT-PCR. Highly positive samples were subjected to virus isolation and seven isolates were fully sequenced. Low pathogenic H9N2 avian influenza virus was introduced in Morocco in 2016. We show that in 2018–2019, the virus was still present irrespective of vaccination status. Phylogenetic and molecular analyses showed mutations related to virulence, although our viruses were related to 2016 Moroccan viruses and grouped in the G1 lineage. Specific amino acid substitutions were identified in Moroccan H9N2 viruses that are believed to lead to increased resistance to antiviral drugs.

Overview of avian influenza virus in urban feral pigeons in Bangkok, Thailand

This survey assessed the presence of avian influenza virus (AIV) in urban feral pigeons (UFPs) in Bangkok, Thailand. A total of 485 UFPs were collected from eight study sites, and blood, tracheal, and cloacal samples were collected from each bird. Virus isolation and molecular methods did not detect AIV in any of the birds tested. A hemagglutination inhibition test was used to test for antibodies to high and low pathogenicity AIV subtypes. AIV subtype H9 antibodies were the only antibodies detected. The overall seroprevalence of AIV subtype H9 antibodies was 6.9%, and subtype H9 antibodies were found in UFPs at all eight sites. The overall geometric mean titer was 11.07 (range: 8–64). These results reveal that UFPs in Bangkok do not currently pose a risk of transmitting AIV to humans. However, monitoring of AIV in UFPs is necessary for disease control and to minimize the possibility of influenza outbreaks.

Transmission dynamics of low pathogenicity avian influenza (H2N2) viruses in live bird markets of the Northeast United States of America, 2013-2019.

Live bird market (LBM) surveillance was conducted in the Northeast United States (US) to monitor for the presence of avian influenza viruses (AIV) in domestic poultry and market environments. A total of 384 H2N2 low pathogenicity AIV (LPAIV) isolated from active surveillance efforts in the LBM system of New York, Connecticut, Rhode Island, New Jersey, Pennsylvania, and Maryland during 2013–2019 were included in this analysis. Comparative phylogenetic analysis showed that a wild-bird-origin H2N2 virus may have been introduced into the LBMs in Pennsylvania and independently evolved since March 2012 followed by spread to LBMs in New York City during late 2012–early 2013. LBMs in New York state played a key role in the maintenance and dissemination of the virus to LBMs in the Northeast US including reverse spread to Pennsylvania LBMs. The frequent detections in the domestic ducks and market environment with viral transmissions between birds and environment possibly led to viral adaptation and circulation in domestic gallinaceous poultry in LBMs, suggesting significant roles of domestic ducks and contaminated LBM environment as reservoirs in maintenance and dissemination of H2N2 LPAIV.

Landscape effects and spatial patterns of avian influenza virus in Danish wild birds, 2006-2020.

Avian influenza (AI) is a contagious disease of birds with zoonotic potential. AI virus (AIV) can infect most bird species, but clinical signs and mortality vary. Assessing the distribution and factors affecting AI presence can direct targeted surveillance to areas at risk of disease outbreaks, or help identify disease hotspots or areas with inadequate surveillance. Using virus surveillance data from passive and active AIV wild bird surveillance, 2006−2020, we investigated the association between the presence of AIV and a range of landscape factors and game bird release. Furthermore, we assessed potential bias in the passive AIV surveillance data submitted by the public, via factors related to public accessibility. Lastly, we tested the AIV data for possible hot‐ and cold spots within Denmark. The passive surveillance data was biased regarding accessibility to areas (distance to roads, cities and coast) compared to random locations within Denmark. For both the passive and active AIV surveillance data, we found significant (p < .01) associations with variables related to coast, wetlands and cities, but not game bird release. We used these variables to predict the risk of AIV presence throughout Denmark, and found high‐risk areas concentrated along the coast and fjords. For both passive and active surveillance data, low‐risk clusters were mainly seen in Jutland and northern Zealand, whereas high‐risk clusters were found in Jutland, Zealand, Funen and the southern Isles such as Lolland and Falster. Our results suggest that landscape affects AIV presence, as coastal areas and wetlands attract waterfowl and migrating birds and therefore might increase the potential for AIV transmission. Our findings have enabled us to create risk maps of AIV presence in wild birds and pinpoint high‐risk clusters within Denmark. This will aid targeted surveillance efforts within Denmark and potentially aid in planning the location of future poultry farms.

A Decade of Avian Influenza in Bangladesh: Where Are We Now?

Highly pathogenic avian influenza (HPAI) has been a public health threat in Bangladesh since the first reported outbreak in poultry in 2007. The country has undertaken numerous efforts to detect, track, and combat avian influenza viruses (AIVs). The predominant genotype of the H5N1 viruses is clade 2.3.2.1a. The persistent changing of clades of the circulating H5N1 strains suggests probable mutations that might have been occurring over time. Surveillance has provided evidence that the virus has persistently prevailed in all sectors and caused discontinuous infections. The presence of AIV in live bird markets has been detected persistently. Weak biosecurity in the poultry sector is linked with resource limitation, low risk perception, and short-term sporadic interventions. Controlling avian influenza necessitates a concerted multi-sector ‘One Health’ approach that includes the government and key stakeholders.

Immunopathological immunohistochemical study of low pathogenic avian influenza virus H5N1 infection in lovebirds (Agapornis spp.) in Indonesia.

Background and Aim:To date, persistent infection with low pathogenic avian influenza virus (AIV) subtype H5N1 (LPAI H5N1) in chickens is widespread in Indonesia. Commercially available ornamental birds on markets play an important role in triggering the occurrence of AIV outbreaks. Thus, the presence of AIV in ornamental birds such as lovebirds needs to be closely monitored. Here, the presence of LPAI H5N1 was investigated in lovebirds with no clinical signs that, although apparently healthy, can be a continuous source of AIV transmission to other sensitive birds such as chickens and even humans.Materials and Methods:In the present study, 30 lovebirds were necropsied. The immunopathology of the lungs, which had hemorrhages, was immunohistochemically studied using the streptavidin-biotin (SB) method to stain for LPAI H5N1. Polyclonal antibodies against the nucleoprotein or monoclonal antibodies against the hemagglutinin of the AIV subtype H5N1 were used to identify these antigens in lung tissue samples.Results:LPAI H5N1 was detected in the lungs of all lovebirds according to the brownish colored deposits in the histological samples. The highest intensity of the SB staining was found in the lumina of vascular capillaries and the cell membranes of air capillaries. The discovery of LPAI H5N1 in lovebirds increases the environmental health risk and raises the possibility of exposure to AIV. Thus, it is very important to improve the mechanisms that control the traffic of ornamental birds between regions and islands, as well as the AIV vaccination strategies related to the prevention, control, and eradication of AIV in Indonesia, and these procedures should be reevaluated.Conclusion:The present study proves that lovebirds are infected with LPAI subtype H5N1. Even if ornamental birds such as lovebirds do not show any clinical signs, they are likely to be a persistently infected with LPAI H5N1. Therefore, ornamental birds might be a continuous source of LPAI H5N1 infections in other sensitive birds, including poultry, and may also be responsible for virus transmission to humans.

Age-dependent pathogenesis of clade 2.3.4.4A H5N2 HPAIV in experimentally infected Broad Breasted White turkeys

Highly pathogenic avian influenza (HPAI) is a viral disease with devastating consequences to the poultry industry as it results in high morbidity, mortality and international trade restrictions. In the present study, we characterized age-related differences in terms of pathology in commercial white broad breasted turkeys inoculated with A/turkey/Minnesota/12582/2015 (H5N2) HPAIV clade 2.3.4.4A, a virus from the largest HPAI poultry outbreak that affected the Unites States in 2014–2015. Turkeys infected at 6-weeks of age showed inapparent to little clinical signs with rapid disease progression, reaching 100% mortality at 3 days post infection (dpi). In contrast, turkeys infected at 16-weeks of age developed ataxia and lethargy and reached 100% mortality by 5 dpi. Infection in the 6-weeks old turkeys resulted in peracute lesions consistent of extensive hemorrhages, edema and necrosis, but inflammation was not prominent. In the 16-weeks old turkeys, necrosis and hemorrhages in tissues were accompanied by a more prominent subacute inflammatory infiltrate. Both age groups showed presence of avian influenza virus (AIV) nucleoprotein (NP) in multiple cell types including neurons, glial cells, ependymal cells, respiratory epithelial cells, air capillary epithelium and pulmonary macrophages, cardiac myocytes, smooth muscle fibers, pancreatic acini and ductal cells. Cells of the vascular walls stained strongly positive for viral antigens, but no positivity was found in the endothelial cells of any organs. These findings indicate that age is a determinant factor in the progression of the disease and delay of mortality during infection with the H5N2 clade 2.3.4.4A HPAI virus in naïve white broad breasted turkeys.

H5N8 AVIAN INFLUENZA VIRUS IN ASWAN GOVERNORATE

Egypt has experienced outbreaks of avian influenza (AI) since 2006. Tracheal and cloacal swabs were collected from three hundred and thirty four domestic poultry (one hundred and sixty eight ducks, one hundred and fifty six chickens, ten geese) from 50 houses from different parts in Aswan governorate. Tracheal and cloacal swabs were examined for the presence of avian influenza virus by real-time RT-PCR. H5N8 genome was detected in 26 out of 334 examined birds, giving a ratio of 7.7%. The species wise distribution of RT-PCR results was 8.3%, 7.6%, 0.0% for ducks, chickens and geese respectively. Clinical signs of avian influenza were appeared on most of positive cases which have been examined for AI in the form of: significant mortality may be as high as 100% within 3-4 days after infection, respiratory signs such as (cough, sneezing and respiratory discharge), swelling and cyanosis in comb and wattles and some birds that survive longer exhibit nervous signs. The main clinical feature in ducks was nervous signs (torticollis, other unusual positions of the head and complete reluctance to move) with high mortality rate from 50% up to 100%. In conclusion, the predominance of H5 infection indicates a need for continuous monitoring of AIV among avian species and the awareness against public health risk.

Co-infection of highly pathogenic avian influenza and duck hepatitis viruses in Egyptian backyard and commercial ducks

Highly pathogenic avian influenza (HPAI) H5N1 virus poses a major challenge to the poultry industry and human health in Egypt. Twenty one households and eight duck farms in Sharkia Province, Egypt were investigated for the presence of avian influenza virus (AIV) and/or duck hepatitis virus 1 (DHV-1). Mortality rates among the investigated farms and yards were, 18.9% (69/365) of native ducks, 60.9% (25/41) of Pekin ducks, 60.2% (6306/10473) of Muscovy ducks and 44.9% (1353/3015) of Mallard ducks. The RT-PCR revealed the circulation of HPAI-H5N1 virus (81/104) among the examined birds with a high percentage in Muscovy (83.7%) and Pekin (83.4%) ducks. Interestingly, co-infection of HPAI and DHV-1 viruses in three ducklings with age of 4–19 days was detected. Severe neurological signs with high mortality were observed in ducklings as early as 4 days of age. Influenza virus antigen was detected in the neurons and glial cells of the brain, hepatocytes, and the intestinal submucosal plexus. Although, genetic characterization of H5N1 isolates revealed HPAIV of clade 2.2.1.2, such increased mortalities and neurological signs regardless of the duck age might imply the natural selection of HPAI in ducks. Crucial monitoring of the disease situation in ducks is essential for the implementation of an effective prevention and control program.

Serological survey of avian influenza virus infection of unvaccinated backyard chickens in Mandlhakazi, Southern Mozambique

ObjectiveTo investigate serologically the presence of avian influenza virus (AIV) in backyard chickens from Mandlhakazi district, Southern Mozambique. MethodsA total of 439 sera samples from unvaccinated and apparently healthy backyard chickens from 4 villages (Chidenguele, Macuacua, Chizavane, and Nwadjahane) were tested for the presence of AIV antibodies through commercial enzyme-linked immunoabsorbent assay (ELISA) kit used according to manufacturer instructions. ResultsAnti-AIV antibodies were detected in all villages surveyed. The overall seroprevalence obtained was 32.6% (95% CI 28.2%–37.0%). The highest prevalence of 51.3% (95% CI 42.3%–60.2%) was recorded in Macuacua village, while the lowest prevalence of 13.0% (95% CI 6.2%–19.9%) was found in Chizavane village. The results of logistic regression analyses suggested that chicken being located in Chizavane and Macuacua villages were more unlikely for getting the virus exposure (P < 0.05). ConclusionsOur findings suggested that AIV is widespread within backyard chickens in the studied villages. Further research is needed to identify the circulating virus genotypes and determine the potential role of backyard chickens in the zoonotic transmission of AIV in Mozambique.

Endemicity of avian influenza in ducks living around commercial layer farms

The progenitors of all avian influenza viruses are generally derived from ducks or other waterfowl that have undergone mutation and adaptation to become pathogenic in chickens or other poultry. Investigation of the presence of avian influenza viruses in ducks especially those living around chicken farms is, therefore, important. Serum from 54 ducks and 51 Muscovy ducks living around commercial layer farms in the districts of Cianjur and Sukabumi were collected in March - April 2014. The indication of AI-virus infection in those birds was based on an array of serological tests including competitive and indirect ELISAs for antibody to nucleoprotein, MM2e ELISA for antibody to M2e, HI test, ELISAs and dot blot for antibodies to haemagglutinin, and dot blot assay for antibodies to neuraminidase. Recombinant Haemagglutinins (H1-H13 and H15), recombinant neuraminidases (N1, N2, N7 and N9) and recombinant influenza-A nucleoprotein were used in the indirect ELISAs and dot blot assays. As many as 63% of duck samples and 13% Muscovy-duck samples were serologically positive to nucleoprotein, and 62% of the nucleoprotein-seropositive ducks were also positive to M2e. The high seroprevalence of AI in the ducks living around commercial poultry farms suggested that application of strict biosecurity measures on those farms is still needed. Based on the results of the ELISA and dot blot assays, AI virus subtypes H9N2 and H5N2, in addition to H5N1, were suspected to be circulating in those ducks. Further confirmation by virus isolation, however, is required because H9N2 and H5N2 subtypes have yet been unknown Indonesia and both the subtypes can cause serious disease in poultry. Ke y Words : Duck, Immunoassay, Avian Influenza, H5N1, H5N2, H9N2

Investigation of avian influenza virus in poultry and wild birds due to novel avian-origin influenza A(H10N8) in Nanchang City, China

Multiple reassortment events within poultry and wild birds had resulted in the establishment of another novel avian influenza A(H10N8) virus, and finally resulted in human death in Nanchang, China. However, there was a paucity of information on the prevalence of avian influenza virus in poultry and wild birds in Nanchang area. We investigated avian influenza virus in poultry and wild birds from live poultry markets, poultry countyards, delivery vehicles, and wild-bird habitats in Nanchang. We analyzed 1036 samples from wild birds and domestic poultry collected from December 2013 to February 2014. Original biological samples were tested for the presence of avian influenza virus using specific primer and probe sets of H5, H7, H9, H10 and N8 subtypes by real-time RT-PCR. In our analysis, the majority (97.98%) of positive samples were from live poultry markets. Among the poultry samples from chickens and ducks, AIV prevalence was 26.05 and 30.81%, respectively. Mixed infection of different HA subtypes was very common. Additionally, H10 subtypes coexistence with N8 was the most prevalent agent during the emergence of H10N8. This event illustrated a long-term surveillance was so helpful for pandemic preparedness and response.

Investigation of avian influenza infections in wild birds, poultry and humans in Eastern Dongting Lake, China.

We investigated avian influenza infections in wild birds, poultry, and humans at Eastern Dongting Lake, China. We analyzed 6,621 environmental samples, including fresh fecal and water samples, from wild birds and domestic ducks that were collected from the Eastern Dongting Lake area from November 2011 to April 2012. We also conducted two cross-sectional serological studies in November 2011 and April 2012, with 1,050 serum samples collected from people exposed to wild birds and/or domestic ducks. Environmental samples were tested for the presence of avian influenza virus (AIV) using quantitative PCR assays and virus isolation techniques. Hemagglutination inhibition assays were used to detect antibodies against AIV H5N1, and microneutralization assays were used to confirm these results. Among the environmental samples from wild birds and domestic ducks, AIV prevalence was 5.19 and 5.32%, respectively. We isolated 39 and 5 AIVs from the fecal samples of wild birds and domestic ducks, respectively. Our analysis indicated 12 subtypes of AIV were present, suggesting that wild birds in the Eastern Dongting Lake area carried a diverse array of AIVs with low pathogenicity. We were unable to detect any antibodies against AIV H5N1 in humans, suggesting that human infection with H5N1 was rare in this region.

Epidemiological investigations on the role of clinically healthy racing pigeons as a reservoir for avian paramyxovirus-1 and avian influenza virus

Clinically healthy racing pigeons may harbour notifiable pathogens and serve as an unnoticed reservoir. Thus, 3480 healthy racing pigeons from 172 different lofts were monitored over a period of 2 years for the presence of avian influenza virus (AIV) and avian paramyxovirus-1 (APMV-1). Pharyngeal and cloacal swabs as well as blood samples were collected from juvenile and adult pigeons. Pools of five pharyngeal swabs per loft and age group were initially screened by real-time reverse transcriptase-polymerase chain reaction (rRT-PCR). Pharyngeal and cloacal samples from lofts that were positive or suspect in the AIV rRT-PCR or the APMV-1 rRT-PCR were inoculated into embryonated chicken eggs for virus isolation. In addition, sera were examined for antibodies against AIV by enzyme-linked immunosorbent assay. The antibody levels after vaccination against APMV-1 were determined by haemagglutination inhibition assay. Of the investigated lofts, 0.0 to 1.4% were positive by rRT-PCR for APMV-1 and 0.0 to 6.7% for AIV during this 2-year period with a total of four samplings. No sample yielded replicating virus in egg culture. No antibodies against AIV were detected. Haemagglutination inhibition test of vaccinated racing pigeons indicated age-dependent APMV-1 titres. The results suggest that the examined racing pigeons may have had contact with AIV, but virus replication may have been too low to induce detectable circulating antibody levels. Only a low percentage of samples were positive for APMV-1, but two outbreaks were observed in monitored flocks, indicating ongoing circulation of APMV-1 in the racing pigeon population. These observations highlight the relevance of APMV-1 vaccination and indicate the importance of flock immunity.

Avian Influenza Virus Investigation in Wild Bobwhite Quail from Texas

The objective of this study was to determine the prevalence of avian influenza viruses (AIV) in bobwhite quail (Colinus virginianus) populations from the rolling plains of Texas, U. S. A. A total of 1320 swab samples (652 tracheal swabs and 668 cloacal swabs) and 44 serum samples were collected from wild-captured or hunter-harvested bobwhite quail from November 2009 to April 2011 at the Rolling Planes Quail Research Ranch, Fisher County, Texas, U. S. A. The presence of AIV in the swabs was determined by real-time reverse-transcription-PCR (rRT-PCR) and all samples positive or suspicious by rRT-PCR were further processed for virus isolation in embryonated chicken eggs. A total of 18 (1.4%) swab samples tested positive for AIV by rRT-PCR (cycle threshold [Ct] values < 35): 13 cloacal swabs (1.9%) and 5 tracheal swabs (0.8%). In addition, 100 (7.6%) swab samples were considered suspicious (Ct values 35.1-40): 69 cloacal swabs (10.3%) and 31 tracheal swabs (4.7%). No virus was isolated from any of the rRT-PCR-positive or suspicious samples tested. Additionally, 44 serum samples were screened for AIV antibodies and were negative. The results presented here indicate low prevalence of AIV in wild populations of bobwhite quail.

Surveillance of avian influenza viruses in wild Ducks and Geese in the Bangweulu wetlands of Zambia

Avian influenza is a highly contagious acute respiratory disease of avian origin and is of major economic and public health importance. Out of all the 16 haemagglutinin subtypes of influenza viruses, only H5 and H7 are considered highly pathogenic in poultry. However, previous studies have reported that serotype H9N2 produces severe respiratory and reproductive tract infections in chickens. Previous studies have suggested that poultry movement through trade and migratory wild birds play a major role in the spread of avian influenza viruses over long distances. Surveillance studies among wild ducks and geese in many parts of the world have always resulted in the isolation of a broad spectrum of avian influenza virus subtypes. Although avian influenza has not yet been reported in Zambia, its outbreak would be devastating to the local economy. The present study was carried out to determine the presence of avian influenza viruses in the wild migratory ducks and geese on the Bangweulu wetlands of Zambia located in Luapula and Northern provinces of Zambia during 2009-2010. A total of 2,000 environmental samples of fresh faeces of wild ducks and geese on the Bangweulu wetlands of Zambia were examined and analysed for the presence of avian influenza viruses. The study found that H6N2 and H9N2 subtypes were present in the faeces of the Knob-billed ducks (Sarkidiornis melanotos). These data indicated that wild migratory ducks that inhabit the Bangweulu wetlands play a role as carriers of influenza viruses, thus necessitating continued surveillance studies so as to elucidate the ecology of the viruses in the area.