Prevalence of Avian Influenza A(H5) and A(H9) Viruses in Live Bird Markets, Bangladesh

Modelling the transmission dynamics of H9N2 avian influenza viruses in a live bird market

H9N2 avian influenza viruses (AIVs) are a major concern for the poultry sector and human health in countries where this subtype is endemic. By fitting a model simulating H9N2 AIV transmission to data from a field experiment, we characterise the epidemiology of the virus in a live bird market in Bangladesh. Many supplied birds arrive already exposed to H9N2 AIVs, resulting in many broiler chickens entering the market as infected, and many indigenous backyard chickens entering with pre-existing immunity. Most susceptible chickens become infected within one day spent at the market, owing to high levels of viral transmission within market and short latent periods, as brief as 5.3 hours. Although H9N2 AIV transmission can be substantially reduced under moderate levels of cleaning and disinfection, effective risk mitigation also requires a range of additional interventions targeting markets and other nodes along the poultry production and distribution network.

EPINEST, an agent-based model to simulate epidemic dynamics in large-scale poultry production and distribution networks

The rapid intensification of poultry production raises important concerns about the associated risks of zoonotic infections. Here, we introduce EPINEST (EPIdemic NEtwork Simulation in poultry Transportation systems): an agent-based modelling framework designed to simulate pathogen transmission within realistic poultry production and distribution networks. We provide example applications to broiler production in Bangladesh, but the modular structure of the model allows for easy parameterization to suit specific countries and system configurations. Moreover, the framework enables the replication of a wide range of eco-epidemiological scenarios by incorporating diverse pathogen life-history traits, modes of transmission and interactions between multiple strains and/or pathogens. EPINEST was developed in the context of an interdisciplinary multi-centre study conducted in Bangladesh, India, Vietnam and Sri Lanka, and will facilitate the investigation of the spreading patterns of various health hazards such as avian influenza, Campylobacter, Salmonella and antimicrobial resistance in these countries. Furthermore, this modelling framework holds potential for broader application in veterinary epidemiology and One Health research, extending its relevance beyond poultry to encompass other livestock species and disease systems.

Epidemiological distribution of respiratory viral pathogens in marketable vaccinated broiler chickens in five governorates in the Nile Delta, Egypt, from January 2022 to October 2022

Background and Aim

Respiratory viral infections significantly negatively impact animal welfare and have significant financial implications in the poultry industry. This study aimed to determine the frequency of the most economically relevant respiratory viruses that circulated in Egyptian chicken flocks in 2022.

Materials and Methods

Chickens from 359 broiler flocks in five different Egyptian governorates in the Nile Delta (Beheira, Gharbia, Giza, Monufiya, and Qalyoubia) at marketing time (33-38 days of age) were used in this study. Combined oropharyngeal and cloacal swabs and tissue samples were collected from clinically diseased or freshly dead birds suffering from respiratory disease. Avian influenza (AI)-H5, AI-H9, Newcastle disease (ND), and infectious bronchitis virus (IBV) were analyzed by reverse transcriptase polymerase chain reaction.

Results

Of the 359 flocks examined, 293 tested positive, whereas 66 were completely negative for the four viruses evaluated, with the highest positive results in Beheira. Out of 293 positive flocks, 211 were positive for a single virus, with Beheira having the highest rate, followed by Qalyoubia, Giza, and Monufiya. ND virus (NDV) was found to be the highest across all governorates, followed by IBV, AI-H9, and AI-H5. A double infection was detected in 73 flocks with either H9 or ND, or both H9 and IB could coinfect each other. The most common viral coinfections were H9 + IB, ND + IB, and ND + H9. Giza had the highest prevalence of ND + H9, H9 + IB, and ND + IB coinfection in the governorates, followed by Monufiya and Beheira. Only six out of 359 flocks were tribally infected with ND + H9 + IB in Giza, Monufiya, and Beheira governorates. On the basis of the number of flocks and the month of the year, July had the lowest number of flocks (23), while September and October had the highest number (48 flocks). Positive flock numbers were highest in October and lowest in January.

Conclusion

From January to October 2022, prevalent respiratory viral infections (H5N1, NDV, H9N2, and IBV) were detected in broiler chickens across the Delta area governorate, according to the findings of the present study. In addition, IBV and H9, either alone or in combination, significantly contributed to the respiratory infection observed in broiler chickens. Regardless of the type and origin of the vaccine used, it is not possible to protect broiler chickens from the development of the infection and the subsequent dissemination of the virus into the poultry environment. In the presence of face-infectious field virus mutations, poultry vaccinations must be regularly reviewed and updated, and poultry farms must take further biosecurity measures.

Prevalence of Antimicrobial Resistance in Escherichia coli and Salmonella Species Isolates from Chickens in Live Bird Markets and Boot Swabs from Layer Farms in Timor-Leste

The rapid emergence of antimicrobial resistance is a global concern, and high levels of resistance have been detected in chicken populations worldwide. The purpose of this study was to determine the prevalence of antimicrobial resistance in Escherichia coli and Salmonella spp. isolated from healthy chickens in Timor-Leste. Through a cross-sectional study, cloacal swabs and boot swabs were collected from 25 live bird markets and two layer farms respectively. E. coli and Salmonella spp. from these samples were tested for susceptibility to six antimicrobials using a disk diffusion test, and a subset was tested for susceptibility to 27 antimicrobials using broth-based microdilution. E. coli and Salmonella spp. isolates showed the highest resistance towards either tetracycline or ampicillin on the disk diffusion test. E. coli from layer farms (odds ratio:5.2; 95%CI 2.0-13.1) and broilers (odds ratio:18.1; 95%CI 5.3-61.2) were more likely to be multi-drug resistant than those from local chickens. Based on the broth-based microdilution test, resistance to antimicrobials in the Timor-Leste Antimicrobial Guidelines for humans were low, except for resistance to ciprofloxacin in Salmonella spp. (47.1%). Colistin resistance in E. coli was 6.6%. Although this study shows that antimicrobial resistance in chickens was generally low in Timor-Leste, there should be ongoing monitoring in commercial chickens as industry growth might be accompanied with increased antimicrobial use.

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.

Live poultry markets beyond health risks: Understanding consumer preferences for live poultry in South China

Live poultry markets (LPMs) are veterinary and public health risks because of potential for zoonotic spillover of pathogens from diseased animals to humans. To control these health risks, veterinary and public health authorities in Asia, including China, have closed or restricted LPMs. In south China, however, LPM closure has been opposed or rendered infeasible by consumers who prefer to purchase live poultry. Previous scholarship has suggested this preference is due to cultural values of freshness. In this study, we present results from detailed interviews with shoppers in south China, including those who prefer live poultry and those who prefer pre-slaughtered poultry. We argue that broader concerns about food safety and quality, rather than freshness alone, drive the demand for LPMs. Live poultry provide sensory information that enable shoppers to evaluate safety and quality in ways that are not possible with pre-slaughtered, refrigerated meat. Based on these findings, we suggest that hygienic interventions into LPMs should recognize that not only freshness, but also trust, must be constructed and maintained in any intervention.

Potential risk zones and climatic factors influencing the occurrence and persistence of avian influenza viruses in the environment of live bird markets in Bangladesh

Live bird markets (LBMs) are critical for poultry trade in many developing countries that are regarded as hotspots for the prevalence and contamination of avian influenza viruses (AIV). Therefore, we conducted weekly longitudinal environmental surveillance in LBMs to determine annual cyclic patterns of AIV subtypes, environmental risk zones, and the role of climatic factors on the AIV presence and persistence in the environment of LBM in Bangladesh. From January 2018 to March 2020, we collected weekly fecal and offal swab samples from each LBM and tested using rRT-PCR for the M gene and subtyped for H5, H7, and H9. We used Generalized Estimating Equations (GEE) approaches to account for repeated observations over time to correlate the AIV prevalence and potential risk factors and the negative binomial and Poisson model to investigate the role of climatic factors on environmental contamination of AIV at the LBM. Over the study period, 37.8% of samples tested AIV positive, 18.8% for A/H5, and A/H9 was, for 15.4%. We found the circulation of H5, H9, and co-circulation of H5 and H9 in the environmental surfaces year-round. The Generalized Estimating Equations (GEE) model reveals a distinct seasonal pattern in transmitting AIV and H5. Specifically, certain summer months exhibited a substantial reduction of risk up to 70-90% and 93-94% for AIV and H5 contamination, respectively. The slaughtering zone showed a significantly higher risk of contamination with H5, with a three-fold increase in risk compared to bird-holding zones. From the negative binomial model, we found that climatic factors like temperature and relative humidity were also significantly associated with weekly AIV circulation. An increase in temperature and relative humidity decreases the risk of AIV circulation. Our study underscores the significance of longitudinal environmental surveillance for identifying potential risk zones to detect H5 and H9 virus co-circulation and seasonal transmission, as well as the imperative for immediate interventions to reduce AIV at LBMs in Bangladesh. We recommend adopting a One Health approach to integrated AIV surveillance across animal, human, and environmental interfaces in order to prevent the epidemic and pandemic of AIV.

Epidemiology and phylodynamics of multiple clades of H5N1 circulating in domestic duck farms in different production systems in Bangladesh

Waterfowl are considered to be natural reservoirs of the avian influenza virus (AIV). However, the dynamics of transmission and evolutionary patterns of AIV and its subtypes within duck farms in Bangladesh remain poorly documented. Hence, a cross-sectional study was conducted in nine districts of Bangladesh between 2019 and 2021, to determine the prevalence of AIV and its subtypes H5 and H9, as well as to identify risk factors and the phylodynamics of H5N1 clades circulating in domestic duck farms. The oropharyngeal and cloacal swab samples were tested for the AIV Matrix gene (M-gene) followed by H5, H7, and H9 subtypes using rRT-PCR. The exploratory analysis was performed to estimate AIV and its subtype prevalence in different production systems, and multivariable logistic regression model was used to identify the risk factors that influence AIV infection in ducks. Bayesian phylogenetic analysis was conducted to generate a maximum clade credibility (MCC) tree and the maximum likelihood method to determine the phylogenetic relationships of the H5N1 viruses isolated from ducks. AIV was detected in 40% (95% CI: 33.0-48.1) of the duck farms. The prevalence of AIV was highest in nomadic ducks (39.8%; 95% CI: 32.9-47.1), followed by commercial ducks (24.6%; 95% CI: 14.5-37.3) and backyard ducks (14.4%; 95% CI: 10.5-19.2). The H5 prevalence was also highest in nomadic ducks (19.4%; 95% CI: 14.0-25.7). The multivariable logistic regression model revealed that ducks from nomadic farms (AOR: 2.4; 95% CI: 1.45-3.93), juvenile (AOR: 2.2; 95% CI: 1.37-3.61), and sick ducks (AOR: 11.59; 95% CI: 4.82-32.44) had a higher risk of AIV. Similarly, the likelihood of H5 detection was higher in sick ducks (AOR: 40.8; 95% CI: 16.3-115.3). Bayesian phylogenetic analysis revealed that H5N1 viruses in ducks belong to two distinct clades, 2.3.2.1a, and 2.3.4.4b. The clade 2.3.2.1a (reassorted) has been evolving silently since 2015 and forming at least nine subgroups based on >90% posterior probability. Notably, clade 2.3.4.4b was introduced in ducks in Bangladesh by the end of the year 2020, which was genetically similar to viruses detected in wild birds in Japan, China, and Africa, indicating migration-associated transmission of an emerging panzootic clade. We recommend continuing AIV surveillance in the duck production system and preventing the intermingling of domestic ducks with migratory waterfowl in wetlands.

Epidemiology and molecular characterization of avian influenza A viruses H5N1 and H3N8 subtypes in poultry farms and live bird markets in Bangladesh

Avian influenza virus (AIV) remains a global threat, with waterfowl serving as the primary reservoir from which viruses spread to other hosts. Highly pathogenic avian influenza (HPAI) H5 viruses continue to be a devastating threat to the poultry industry and an incipient threat to humans. A cross-sectional study was conducted in seven districts of Bangladesh to estimate the prevalence and subtypes (H3, H5, and H9) of AIV in poultry and identify underlying risk factors and phylogenetic analysis of AIVs subtypes H5N1 and H3N8. Cloacal and oropharyngeal swab samples were collected from 500 birds in live bird markets (LBMs) and poultry farms. Each bird was sampled by cloacal and oropharyngeal swabbing, and swabs were pooled for further analysis. Pooled samples were analyzed for the influenza A virus (IAV) matrix (M) gene, followed by H5 and H9 molecular subtyping using real-time reverse transcription-polymerase chain reaction (rRT-PCR). Non-H5 and Non-H9 influenza A virus positive samples were sequenced to identify possible subtypes. Selected H5 positive samples were subjected to hemagglutinin (HA) and neuraminidase (NA) gene sequencing. Multivariable logistic regression was used for risk factor analysis. We found that IAV M gene prevalence was 40.20% (95% CI 35.98-44.57), with 52.38%, 46.96%, and 31.11% detected in chicken, waterfowl, and turkey, respectively. Prevalence of H5, H3, and H9 reached 22%, 3.4%, and 6.9%, respectively. Waterfowl had a higher risk of having AIV (AOR: 4.75), and H5 (AOR: 5.71) compared to chicken; more virus was detected in the winter season than in the summer season (AOR: 4.93); dead birds had a higher risk of AIVs and H5 detection than healthy birds, and the odds of H5 detection increased in LBM. All six H5N1 viruses sequenced were clade 2.3.2.1a-R1 viruses circulating since 2015 in poultry and wild birds in Bangladesh. The 12 H3N8 viruses in our study formed two genetic groups that had more similarity to influenza viruses from wild birds in Mongolia and China than to previous H3N8 viruses from Bangladesh. The findings of this study may be used to modify guidelines on AIV control and prevention to account for the identified risk factors that impact their spread.

H9N2 avian influenza virus dispersal along Bangladeshi poultry trading networks

Avian influenza virus subtype H9N2 is endemic in Bangladesh's poultry population. The subtype affects poultry production and poses a potential zoonotic risk. Insufficient understanding of how the poultry trading network shapes the dissemination of avian influenza viruses has hindered the design of targeted interventions to reduce their spread. Here, we use phylodynamic analyses of haemagglutinin sequences to investigate the spatial spread and dispersal patterns of H9N2 viruses in Bangladesh's poultry population, focusing on its two largest cities (Dhaka and Chattogram) and their poultry production and distribution networks. Our analyses suggest that H9N2 subtype avian influenza virus lineage movement occurs relatively less frequently between Bangladesh's two largest cities than within each city. H9N2 viruses detected in single markets are often more closely related to viruses from other markets in the same city than to each other, consistent with close epidemiological connectivity between markets. Our analyses also suggest that H9N2 viruses may spread more frequently between chickens of the three most commonly sold types (sunali-a cross-bred of Fayoumi hen and Rhode Island Red cock, deshi-local indigenous, and exotic broiler) in Dhaka than in Chattogram. Overall, this study improves our understanding of how Bangladesh's poultry trading system impacts avian influenza virus spread and should contribute to the design of tailored surveillance that accommodates local heterogeneity in virus dispersal patterns.

Prevalence of the H5N8 influenza virus in birds: Systematic review with meta-analysis

INTRODUCTION

Avian influenza viruses are members of the Orthomyxoviridae family, considered highly pathogenic (HPAI). They result from genetic variations from their low virulence predecessors. HPAI is a global problem. Large outbreaks of HAPI have significant health and economic impacts.

OBJECTIVE

The objective of this study was to assess the prevalence of the H5N8 Influenza virus in birds, as well as to assess its variability according to the countries and years.

METHODS

A systematic review of the literature was carried out in six databases (Web of Sciences, Scopus, PubMed, SciELO, Lilacs and Google Scholar) to evaluate the proportion of birds infected with the H5N8 Influenza virus, by molecular and immunological techniques. A meta-analysis was performed using a random-effects model to calculate the pooled prevalence, 95% confidence intervals (95%CI). A 2-tailed 5% alpha level was used for hypothesis testing. Measures of heterogeneity were estimated and reported, including the Cochrane Q statistic, the I² index, and the tau-squared test. In addition, bird species performed subgroup analyzes.

RESULTS

152 data groups were analyzed, a combined prevalence of 1.6% (95% CI 1.3-1.9%) was found for molecular studies, and the ELISA study yielded a seroprevalence of 66.7%; those results of molecular detection varied by year, from 0.2% in 2014 to 52.6% in 2020 and 96.9% in 2015.

CONCLUSION

The combined prevalence was substantial because large outbreaks have caused severe economic repercussions. In addition, it is considered a serious concern for public health due to its possible zoonotic activity.

Prevalence and risk factors for avian influenza virus (H5 and H9) contamination in peri-urban and rural live bird markets in Bangladesh

Avian influenza viruses (AIV) have been frequently detected in live bird markets (LBMs) around the world, primarily in urban areas, and have the ability to spillover to other species, including humans. Despite frequent detection of AIV in urban LBMs, the contamination of AIV on environmental surfaces in rural and peri-urban LBMs in Bangladesh is poorly documented. Therefore, we conducted this study to determine the prevalence of AIV subtypes within a subset of peri-urban and rural LBMs in Bangladesh and to further identify associated risk factors. Between 2017 and 2018, we collected faecal and offal samples from 200 stalls in 63 LBMs across four sub-districts. We tested the samples for the AIV matrix gene (M-gene) followed by H5, H7, and H9 subtypes using real-time reverse transcriptase-polymerase chain reaction (rRT-PCR). We performed a descriptive analysis of market cleanliness and sanitation practices in order to further elucidate the relationship between LBM biosecurity and AIV subtypes by species, sample types, and landscape. Subsequently, we conducted a univariate analysis and a generalized linear mixed model (GLMM) to determine the risk factors associated with AIV contamination at individual stalls within LBMs. Our findings indicate that practices related to hygiene and the circulation of AIV significantly differed between rural and peri-urban live bird markets. 42.5% (95% CI: 35.56-49.67) of stalls were positive for AIV. A/H5, A/H9, and A HA/Untyped were detected in 10.5% (95% CI: 6.62-15.60), 9% (95% CI: 5.42-13.85), and 24.0% (95% CI: 18.26-30.53) of stalls respectively, with no detection of A/H7. Significantly higher levels of AIV were found in the Sonali chicken strain compared to the exotic broiler, and in offal samples compared to fecal samples. In the GLMM analysis, we identified several significant risk factors associated with AIV contamination in LBMs at the stall level. These include: landscape (AOR: 3.02; 95% CI: 1.18-7.72), the number of chicken breeds present (AOR: 2.4; 95% CI: 1.01-5.67), source of birds (AOR: 2.35; 95% CI: 1.0-5.53), separation of sick birds (AOR: 3.04; 95% CI: 1.34-6.92), disposal of waste/dead birds (AOR: 3.16; 95% CI: 1.41-7.05), cleaning agent (AOR: 5.99; 95% CI: 2.26-15.82), access of dogs (AOR: 2.52; 95% CI: 1.12-5.7), wild birds observed on site (AOR: 2.31; 95% CI: 1.01-5.3). The study further revealed a substantial prevalence of AIV with H5 and H9 subtypes in peri-urban and rural LBMs. The inadequate biosecurity measures at poultry stalls in Bangladesh increase the risk of AIV transmission from poultry to humans. To prevent the spread of AIV to humans and wild birds, we suggest implementing regular surveillance at live bird markets and enhancing biosecurity practices in peri-urban and rural areas in Bangladesh.

Epidemiology and molecular characterization of avian influenza virus in backyard poultry of Chattogram, Bangladesh

Ducks, the natural reservoir of avian influenza virus (AIV), act as reassortment vessels for HPAI and low pathogenic avian influenza (LPAI) virus for domestic and wild bird species. In Bangladesh, earlier research was mainly focused on AIV in commercial poultry and live bird markets, where there is scanty literature reported on AIV in apparently healthy backyard poultry at the household level. The present cross-sectional study was carried out to reveal the genomic epidemiology of AIV of backyard poultry in coastal (Anowara) and plain land (Rangunia) areas of Bangladesh. We randomly selected a total of 292 households' poultry (having both chicken and duck) for sampling. We administered structured pre-tested questionnaires to farmers through direct interviews. We tested cloacal samples from birds for the matrix gene (M gene) followed by H5 and H9 subtypes using real-time reverse transcriptase-polymerase chain reaction (rRT-PCR). All AIV-positive samples were subjected to four-gene segment sequencing (M, PB1, HA, and NA gene). We found that the prevalence of AIV RNA at the household level was 6.2% (n = 18; N = 292), whereas duck and chicken prevalence was 3.6% and 3.2%, respectively. Prevalence varied with season, ranging from 3.1% in the summer to 8.2% in the winter. The prevalence of subtypes H5 and H9 in backyard poultry was 2.7% and 3.3%, respectively. The phylogenetic analysis of M, HA, NA, and PB1 genes revealed intra-genomic similarity, and they are closely related to previously reported AIV strains in Bangladesh and Southeast Asia. The findings indicate that H5 and H9 subtypes of AIV are circulating in the backyard poultry with or without clinical symptoms. Moreover, we revealed the circulation of 2.3.2.1a (new) clade among the chicken and duck population without occurring outbreak which might be due to vaccination. In addition to routine surveillance, molecular epidemiology of AIV will assist to gain a clear understanding of the genomic evolution of the AIV virus in the backyard poultry rearing system, thereby facilitating the implementation of effective preventive measures to control infection and prevent the potential spillover to humans.

Prevalence and associated risk factors of avian influenza A virus subtypes H5N1 and H9N2 in LBMs of East Java province, Indonesia: a cross-sectional study

Background

Avian influenza A virus subtypes H5N1 and H9N2 are contagious zoonotic diseases that are circulating in Indonesia and have raised increasing concern about their potential impacts on poultry and public health. A cross-sectional study was carried out to investigate the prevalence and associated risk factors of avian influenza A virus subtypes H5N1 and H9N2 among poultry in the live bird markets of four cities in East Java province, Indonesia.

Methods

A total of 600 tracheal and cloacal swabs (267 from backyards, 179 from broilers, and 154 from layers) from healthy birds were collected. The samples were inoculated into specific pathogenic-free embryonated eggs at 9-day-old via the allantoic cavity. qRT-PCR was used for further identification of avian influenza.

Results

The overall prevalence of circulating influenza A virus subtypes H5N1 and H9N2 was 3.8% (23/600, 95%CI [0.0229–0.0537]). Prevalence was higher in backyards at 5.99% (16/267) followed by broilers (2.23% (4/179)) and layers (1.68% (3/154)). The final multivariable model revealed five risk factors for H9N2 infections: presence of ducks (p = 0.003, OR = 38.2), turkeys (p = 0.017 OR = 0.032), and pheasants in the stall (p = 0.04, OR = 18.422), dry (p = 0.006) and rainy season (p < 0.001), and household birds (p = 0.002) and seven factors for H5N1 infections including: observing rodents (p = 0.036, OR = 0.005), stray dogs access (p = 0.004 OR ≤ 0.001), presence of turkeys (p = 0.03 OR = 0.007), chukars/partridges (p = 0.024 OR = 2500), and peafowls in the stalls (p = 0.0043 OR ≤ 0.001), rainy season (p = 0.001) and birds from the household sources (p = 0.002) in the live bird markets.

Conclusions

The findings of the current study illustrate the recurring infection and presence of both avian influenza viruses and associated risk factors in the surveyed marketplaces. Effective protective measures and mitigation strategies for risks outlined in this study could help to reduce the burden of H5N1 and H9N2 AI subtypes into the live bird markets of Indonesia.

Campylobacter positivity and public health risks in live bird markets in Busia, Kenya: A value chain analysis

Live bird markets (LBMs) provide integral hubs for 95% of poultry produced for food. Surveillance systems in LBMs serving smallholder farmers in sub-saharan Africa are often non-functional, and data about public health risks and emerging pathogens are lacking. Studies in Kenya have reported 29-44% Campylobacter prevalence in poultry. We analysed such LBMs in Kenya for likely transmission of Campylobacter from poultry to humans. We conducted a cross-sectional survey among 186 live poultry traders (LPTs) in 14 LBMs in a region with widespread backyard poultry systems. A pretested structured questionnaire was administered to all LPTs having regular contacts with poultry to gather market data and risk information on campylobacteriosis. Campylobacter was detected in individual cloacal cultures and identified through PCR. The median score obtained from the outcome of risk assessment dichotomized respondents into high and low risk categories. We performed logistic regression at 95% confidence interval (CI) to compare market characteristics and Campylobacter positivity to risk categories to identify LBM-associated public health risks. Markets had a median of 13 traders, and mean age of 46.3 ± 13.7 years. Majority 162/186 (87.1%) were males. Market behavioural processes by LPTs varied: Only 58.6% LPTs held bird species separate; onsite slaughter (38.7%); encountered sick-bird (93%) and dead-bird (83%) amidst limited health inspection (31.2%). Campylobacter positivity in live birds was 43/112 (38.4%, 95% CI: 29.4-48.1). Risk information on campylobacteriosis was low 41/114 (36%, 95% CI: 27.2-45.5). Sanitary risks were related to accumulation of litter (adjusted prevalence odds ratio [aPOR]: 19.67, 95% CI: 3.01-128.52). Accessing hand-wash facilities (aPOR: .32, 95% CI: .13-.78) and access to information (aPOR: .24, 95% CI: .09-.61) were protective. Sanitary risks were related to poor hygiene. LBMs could be central surveillance sites for Campylobacter. Public health authorities/actors should consider appropriate targeting to improve sanitary measures and Campylobacter control strategies.

Efficacy of Disinfectants Usage at Daily Live Bird Markets in Four North-Western States of Nigeria

Maintaining strict biosecurity measures are essential in preventing disease spread from live bird markets (LBMs), which serve as a major intermingling area for poultry from different sources. This study evaluated the efficacy of disinfectants used in daily live bird markets of four north-western states in Nigeria. Seven different disinfectants were identified as commonly used in the LBMs. They were analysed by suspension and surface disinfection tests against standard strains of Escherichia coli, Salmonella Enteritidis, and Staphylococcus aureus. Isolates from swab samples of birds’ cages in the LBMs were initially subjected to biochemical tests and, subsequently, susceptibility tests against commercial disinfectants. All of the 7 (100 %) disinfectants used in the LBMs killed/inhibited the growth of E. coli, S. Enteritidis, and S. aureus with the suspension test, while following the surface disinfection test, all 7 (100 %) killed/inhibited the growth of E. coli and S. Enteritidis but only 4 (57 %) killed/inhibited the growth of S. aureus. Seven (0.02 %) samples out of the 400 swabs were positive for E. coli comprising 1 (14 %), 2 (29 %), and 4 (57 %) from LBMs in Katsina, Kaduna, and Kano, respectively. There were varying growths of E. coli at different concentrations and exposure times. Six (17 %) of the LBMs sampled had and used disinfectants. E. coli was isolated from 1 (17 %) out of the 6 LBMs that had and used disinfectants and 5 (17 %) out of the 29 LBMs that did not have or use disinfect-ants. The standard organisms were most susceptible to orthobenzyl chlorophenol-based disinfectants and least susceptible to chlorophenol-based disinfectants. This study has shown the importance of the use of disinfect-ants in LBMs. There should be enforcement of disinfectants usage in LBMs for public safety.

Village and farm-level risk factors for avian influenza infection on backyard chicken farms in Bangladesh

A cross-sectional study was conducted with 144 small-scale poultry farmers across 42 Bangladeshi villages to explore risk factors associated with avian influenza H5 and H9 seropositivity on backyard chicken farms. Using mixed-effects logistic regression with village as random effect, we identified crow abundance in garbage dumping places and presence of migratory wild birds within villages to be associated with higher odds of H5 and H9 seropositivity. At farm-level, garbage around poultry houses was also associated with higher odds of H5 and H9 seropositivity. In addition, specific trading practices (such as, purchase of chickens from live bird markets (LBM) and neighboring farms to raise them on their own farms, frequency of visits to LBM, purchase of poultry at LBM for consumption) and contact of backyard chickens with other animals (such as, feeding of different poultry species together, using pond water as drinking source for poultry, access of feral and wild animals to poultry houses) were associated with higher odds of H5 or H9 seropositivity. Resource-constrained small-scale poultry farmers should be able to address risk factors identified in this study without requiring large investments into poultry management, thereby reducing the likelihood of avian influenza virus transmission and ultimately occurrence of avian influenza outbreaks.

Surveillance of the spread of avian influenza virus type A in live bird markets in Tripoli, Libya, and determination of the associated risk factors

Background and Aim: Studies on avian influenza virus (AIV) in Libya are few and limited. This study aimed to determine the presence of AIV in live bird markets (LBMs) in Tripoli and determine the risk factors associated with AIV spread. Materials and Methods: In total, 269 cloacal swabs were randomly collected from different bird species in 9 LBMs located in Tripoli and its surrounding regions. The target species were ducks, geese, local chickens, Australian chickens, Brahma chickens, turkeys, pigeons, quails, peacock broiler chicks, and pet birds. Total RNA was extracted from the swab samples and used for real-time polymerase chain reaction to detect AIV type A. Results: Of the 269 samples, 28 (10.41% of total samples) were positive for AIV type A. The LBMs with positive samples were Souq Aljumaa, Souq Alkhamees, Souq Althulatha, and Souq Tajoura. The highest percentage (35.71%) of AIV was recorded in Souq Aljumaa. Positive results for AIV type A were obtained primarily in three species of birds: Ducks (14/65; highest percentage: 21.5%), local chickens (12/98; 12.24%), and geese (2/28; 7.14%). Furthermore, the following three risk factors associated with the spread of AIV type A were identified: Time spent by breeders/vendors at the market (odds ratio [OR] = 11.181; 95% confidence interval [CI] = 3.827–32.669), methods used for disposing dead birds (OR = 2.356; 95% CI = 1.005–5.521), and last visited LBM (OR = 0.740; 95% CI = 0.580–0.944). Restricting the movement of poultry vendors from one market to another may protect against AIV spread. Conclusion: The findings of this study indicate the high risk of AIV spread in LBMs and highlight the need for continuous surveillance of LBMs across the country.

Redesign and Validation of a Real-Time RT-PCR to Improve Surveillance for Avian Influenza Viruses of the H9 Subtype

Avian influenza viruses of the H9 subtype cause significant losses to poultry production in endemic regions of Asia, Africa and the Middle East and pose a risk to human health. The availability of reliable and updated diagnostic tools for H9 surveillance is thus paramount to ensure the prompt identification of this subtype. The genetic variability of H9 represents a challenge for molecular-based diagnostic methods and was the cause for suboptimal detection and false negatives during routine diagnostic monitoring. Starting from a dataset of sequences related to viruses of different origins and clades (Y439, Y280, G1), a bioinformatics workflow was optimized to extract relevant sequence data preparatory for oligonucleotides design. Analytical and diagnostic performances were assessed according to the OIE standards. To facilitate assay deployment, amplification conditions were optimized with different nucleic extraction systems and amplification kits. Performance of the new real-time RT-PCR was also evaluated in comparison to existing H9-detection methods, highlighting a significant improvement of sensitivity and inclusivity, in particular for G1 viruses. Data obtained suggest that the new assay has the potential to be employed under different settings and geographic areas for a sensitive detection of H9 viruses.

Semi-Scavenging Poultry as Carriers of Avian Influenza Genes

Ducks are the natural reservoir of influenza A virus and the central host for the avian influenza virus (AIV) subtype H5N1, which is highly pathogenic. Semi-scavenging domestic ducks allow for the reemergence of new influenza subtypes which could be transmitted to humans. We collected 844 cloacal swabs from semi-scavenging ducks inhabiting seven migratory bird sanctuaries of Bangladesh for the molecular detection of avian influenza genes. We detected the matrix gene (M gene) using real-time RT-PCR (RT-qPCR). Subtyping of the AIV-positive samples was performed by RT-qPCR specific for H5, H7, and H9 genes. Out of 844 samples, 21 (2.488%) were positive for AIV. Subtyping of AIV positive samples (n = 21) revealed that nine samples (42.85%) were positive for the H9 subtype, five (23.80%) were positive for H5, and seven (33.33%) were negative for the three genes (H5, H7, and H9). We detected the same genes after propagating the virus in embryonated chicken eggs from positive samples. Semi-scavenging ducks could act as carriers of pathogenic AIV, including the less pathogenic H9 subtype. This can enhance the pathogenicity of the virus in ducks by reassortment. The large dataset presented in our study from seven areas should trigger further studies on AIV prevalence and ecology.

Live bird market in Bangladesh: Regulatory systems and operations

Objective:

In developing countries, such as Bangladesh, the live bird market (LBM) is a vital location for the trading of live poultry. The study was carried out in nine LBMs located around Bangladesh to ascertain the present regulations and procedures governing their operation. Additionally, the responsibilities and levels of engagement of the stakeholders were determined.

Materials and Methods:

The data were gathered through the use of a semi-structured interview guide. Thematic analysis was used to code the interview transcripts iteratively.

Results:

The findings indicated that the government was directly and indirectly involved in the leasing process of the markets. A market in this country is divided into numerous sectors, including LBM, fish market, vegetable market, and grocery stores. A market’s hygienic condition is highly dependent on market authority’s decisions. In some markets, market officials conducted routine sanitary inspections. Veterinarians played a little role in the inspection procedure.

Conclusion:

There is no adequate, functional monitoring system to ensure that LBMs adhere to cleanliness and adequate and functional biosecurity. Biosecurity enhancements, effective cleaning programs, and regular monitoring by relevant authorities are critical for LBMs in Bangladesh.

Prevalence and risk factors of Avian Influenza Viruses among household ducks in Chattogram, Bangladesh

Avian influenza viruses (AIV) increase commercial and backyard poultry mortality and morbidity, reduces egg production, and elevates public health risk. Household ducks propagate and transmit HPAI and LPAI viruses between domesticated and wild birds in Southeast Asian countries, including Bangladesh. This study was conducted to identify epidemiological factors associated with AIV infection among household ducks at Chattogram, Bangladesh. We randomly selected and collected blood and oropharyngeal swab samples from 281 households ducks. We evaluated the serum for AIV antibody using cELISA and tested for H5 and H9 subtypes using the HI test. We tested the swabs with real-time reverse transcriptase PCR (rRT-PCR) for M gene, and H5, H9 subtypes. In the duck populations, the household level AIV sero-prevalence was 57.7% (95% CI: 51.6-63.3) and RNA prevalence was 2.4% (95% CI: 1.0-5.0). H5 and H9 subtype sero-prevalence was 31.5% (95% CI: 22.2-42.0) and 23.9% (95% CI: 15.6-33.9). H5 and H9 subtype RNA prevalence were 0% (95% CI: 0.0-1.3) and 2.4% (95% CI: 1.0-5.0). We determined household-level OR (Odds Ratios) for the "combined (mixed materials-mud and concrete or metallic)" category was 2.2 (95% CI: 1.1-4.2) compared with "wooden/bamboo" category (p = 0.02); 2.8 (95% CI: 1.2-6.6) in households with duck plague vaccine coverage compared with no coverage (p = 0.01); and 2.4 (95% CI: 0.6-9.7) in households that threw dead birds in bushes and the roadside compared with households that buried or threw dead birds in garbage pits (p = 0.21). M gene phylogenetic analysis compared M gene sequences to previously reported Bangladeshi H9N2 isolates. The evidence presented here shows AIV circulation in the Chattogram, Bangladesh study areas. AIV reduction can be achieved through farmer education of proper farm management practices.

Farm-Level Risk Factors Associated With Avian Influenza A (H5) and A (H9) Flock-Level Seroprevalence on Commercial Broiler and Layer Chicken Farms in Bangladesh

A cross-sectional study was conducted to identify farm-level risk factors associated with avian influenza A H5 and H9 virus exposure on commercial chicken farms in Bangladesh. For broiler farms, both H5 and H9 seropositivity were associated with visits by workers from other commercial chicken farms [odds ratio (OR) for H5 = 15.1, 95% confidence interval (CI): 2.8-80.8; OR for H9 = 50.1, 95% CI: 4.5-552.7], H5 seropositivity was associated with access of backyard ducks (OR = 21.5, 95% CI: 2.3-201.1), and H9 seropositivity with a number of farm employees (OR = 9.4, 95% CI: 1.1-80.6). On layer farms, both H5 and H9 seropositivity were associated with presence of stray dogs (OR for H5 = 3.1, 95% CI: 1.1-9.1; OR for H9 = 4.0, 95% CI: 1.1-15.3), H5 seropositivity with hatcheries supplying chicks (OR = 0.0, 95% CI: 0.0-0.3), vehicles entering farms (OR = 5.8, 95% CI: 1.5-22.4), number of farm employees (OR = 5.8, 95% CI: 1.2-28.2), and burying of dead birds near farms (OR = 4.6, 95% CI: 1.2-17.3); H9 seropositivity with traders supplying feed (OR = 5.9, 95% CI: 1.0-33.9), visits conducted of other commercial poultry farms (OR = 4.7, 95% CI: 1.1-20.6), number of spent layers sold (OR = 24.0, 95% CI: 3.7-155.0), and frequency of replacing chicken droppings (OR = 28.3, 95% CI: 2.8-284.2). Policies addressing these risk factors will increase the effectiveness of prevention and control strategies reducing the risk of avian influenza on commercial chicken farms.

Molecular epidemiology and pathogenicity of H5N1 and H9N2 avian influenza viruses in clinically affected chickens on farms in Bangladesh

Avian influenza virus (AIV) subtypes H5N1 and H9N2 co-circulate in poultry in Bangladesh, causing significant bird morbidity and mortality. Despite their importance to the poultry value chain, the role of farms in spreading and maintaining AIV infections remains poorly understood in most disease-endemic settings. To address this crucial gap in our knowledge, we conducted a cross-sectional study between 2017 and 2019 in the Chattogram Division of Bangladesh in clinically affected and dead chickens in farms with suspected AIV infection. Viral prevalence of each subtype was approximately 10% among farms for which veterinary advice was sought, indicating a high level of virus circulation in chicken farms despite the low number of reported outbreaks. The level of co-circulation of both subtypes on farms was high, with our study suggesting that in the field, the co-circulation of H5N1 and H9N2 can modulate disease severity, which could facilitate an underestimated level of AIV transmission in the poultry value chain. Finally, using newly generated whole-genome sequences, we investigate the evolutionary history of a small subset of H5N1 and H9N2 viruses. Our analyses revealed that for both subtypes, the sampled viruses were genetically most closely related to other viruses isolated in Bangladesh and represented multiple independent incursions. However, due to lack of longitudinal surveillance in this region, it is difficult to ascertain whether these viruses emerged from endemic strains circulating in Bangladesh or from neighbouring countries. We also show that amino acids at putative antigenic residues underwent a distinct replacement during 2012 which coincides with the use of H5N1 vaccines.

Frequency and patterns of exposure to live poultry and the potential risk of avian influenza transmission to humans in urban Bangladesh

Avian influenza is endemic in Bangladesh, where greater than 90% of poultry are marketed through live poultry markets (LPMs). We conducted a population-based cross-sectional mobile telephone survey in urban Dhaka, Bangladesh to investigate the frequency and patterns of human exposure to live poultry in LPMs and at home. Among 1047 urban residents surveyed, 74.2% (95% CI 70.9-77.2) reported exposure to live poultry in the past year, with the majority of exposure occurring on a weekly basis. While visiting LPMs was less common amongst females (40.3%, 95% CI 35.0-45.8) than males (58.9%, 95% CI 54.0-63.5), females reported greater poultry exposure through food preparation, including defeathering (13.2%, 95% CI 9.5-17.9) and eviscerating (14.8%, 95% CI 11.2-19.4) (p < 0.001). A large proportion of the urban population is frequently exposed to live poultry in a setting where avian influenza viruses are endemic in LPMs. There is thus not only ample opportunity for spillover of avian influenza infections into humans in Dhaka, Bangladesh, but also greater potential for viral reassortment which could generate novel strains with pandemic potential.

Avian influenza transmission risk along live poultry trading networks in Bangladesh

Live animal markets are known hotspots of zoonotic disease emergence. To mitigate those risks, we need to understand how networks shaped by trading practices influence disease spread. Yet, those practices are rarely recorded in high-risk settings. Through a large cross-sectional study, we assessed the potential impact of live poultry trading networks’ structures on avian influenza transmission dynamics in Bangladesh. Networks promoted mixing between chickens sourced from different farming systems and geographical locations, fostering co-circulation of viral strains of diverse origins in markets. Viral transmission models suggested that the observed rise in viral prevalence from farms to markets was unlikely explained by intra-market transmission alone, but substantially influenced by transmission occurring in upstream network nodes. Disease control interventions should therefore alter the entire network structures. However, as networks differed between chicken types and city supplied, standardised interventions are unlikely to be effective, and should be tailored to local structural characteristics.

Avian Influenza Risk Environment: Live Bird Commodity Chains in Chattogram, Bangladesh

In this paper, we identify behaviours in live bird commodity chains in Chattogram, Bangladesh, which may influence the risk of pathogen emergence and transmission: the nature of poultry trade, value appropriation and selling sick or infected birds. Examining the reasons why actors engage in these behaviours, we emphasise the politics of constraints within a context of real-world decisions, governed by existential and pragmatic agency. Focusing on contact zones and entanglement, analysing patron-client relationships and precarious circumstances, we argue that agency and structure specific to the Bangladeshi context produce a risk environment. Structural constraints may reinforce risky occupational practises and limit individual agency. Structural constraints need to be addressed in order to tackle animal and zoonotic disease risk along live animal commodity chains.

Risk Areas for Influenza A(H5) Environmental Contamination in Live Bird Markets, Dhaka, Bangladesh

We evaluated the presence of influenza A(H5) virus environmental contamination in live bird markets (LBMs) in Dhaka, Bangladesh. By using Bernoulli generalized linear models and multinomial logistic regression models, we quantified LBM-level factors associated with market work zone–specific influenza A(H5) virus contamination patterns. Results showed higher environmental contamination in LBMs that have wholesale and retail operations compared with retail-only markets (relative risk 0.69, 95% 0.51–0.93; p = 0.012) and in March compared with January (relative risk 2.07, 95% CI 1.44–2.96; p<0.001). Influenza A(H5) environmental contamination remains a public health problem in most LBMs in Dhaka, which underscores the need to implement enhanced biosecurity interventions in LBMs in Bangladesh.

Genetic Characterization of Highly Pathogenic Avian Influenza A(H5N8) Virus in Pakistani Live Bird Markets Reveals Rapid Diversification of Clade 2.3.4.4b Viruses

The highly pathogenic (HPAI) avian influenza A(H5N1) viruses have undergone reassortment with multiple non-N1-subtype neuraminidase genes since 2008, leading to the emergence of H5Nx viruses. H5Nx viruses established themselves quickly in birds and disseminated from China to Africa, the Middle East, Europe and North America. Multiple genetic clades have successively evolved through frequent mutations and reassortment, posing a continuous threat to domestic poultry and causing substantial economic losses. Live bird markets are recognized as major sources of avian-to-human infection and for the emergence of zoonotic influenza. In Pakistan, the A(H5N1) virus was first reported in domestic birds in 2007; however, avian influenza surveillance is limited and there is a lack of knowledge on the evolution and transmission of the A(H5) virus in the country. We collected oropharyngeal swabs from domestic poultry and environmental samples from six different live bird markets during 2018–2019. We detected and sequenced HPAI A(H5N8) viruses from two chickens, one quail and one environmental sample in two markets. Temporal phylogenetics indicated that all novel HPAI A(H5N8) viruses belonged to clade 2.3.4.4b, with all eight genes of Pakistan A(H5N8) viruses most closely related to 2017 Saudi Arabia A(H5N8) viruses, which were likely introduced via cross-border transmission from neighboring regions approximately three months prior to virus detection into domestic poultry. Our data further revealed that clade 2.3.4.4b viruses underwent rapid lineage expansion in 2017 and acquired significant amino acid mutations, including mutations associated with increased haemagglutinin affinity to human α-2,6 receptors, prior to the first human A(H5N8) infection in Russian poultry workers in 2020. These results highlight the need for systematic avian influenza surveillance in live bird markets in Pakistan to monitor for potential A(H5Nx) variants that may arise from poultry populations.

Transboundary Animal Diseases, an Overview of 17 Diseases with Potential for Global Spread and Serious Consequences

Animals provide food and other critical resources to most of the global population. As such, diseases of animals can cause dire consequences, especially disease with high rates of morbidity or mortality. Transboundary animal diseases (TADs) are highly contagious or transmissible, epidemic diseases, with the potential to spread rapidly across the globe and the potential to cause substantial socioeconomic and public health consequences. Transboundary animal diseases can threaten the global food supply, reduce the availability of non-food animal products, or cause the loss of human productivity or life. Further, TADs result in socioeconomic consequences from costs of control or preventative measures, and from trade restrictions. A greater understanding of the transmission, spread, and pathogenesis of these diseases is required. Further work is also needed to improve the efficacy and cost of both diagnostics and vaccines. This review aims to give a broad overview of 17 TADs, providing researchers and veterinarians with a current, succinct resource of salient details regarding these significant diseases. For each disease, we provide a synopsis of the disease and its status, species and geographic areas affected, a summary of in vitro or in vivo research models, and when available, information regarding prevention or treatment.

Surveillance on respiratory diseases reveals enzootic circulation of both H5 and H9 avian influenza viruses in small-scale commercial layer farms of Bangladesh

Poultry production in Bangladesh has been experiencing H5N1 highly pathogenic avian influenza (HPAI) and H9N2 low pathogenic avian influenza (LPAI) for the last 14 years. Vaccination of chickens against H5 HPAI is in practice since the end of 2012. Subsequently, the official reporting of HPAI outbreaks gradually decreased. However, the true extent of circulation of avian influenza virus (AIV) in commercial poultry production is not clear. To explore this, we conducted active surveillance in 422 small-scale commercial layer farms in 20 villages of Mymensingh and Tangail districts of Bangladesh during 2017 and 2018 for the presence of diseases with respiratory signs. A total of 88 farms with respiratory disease problems were identified and investigated during the surveillance. In addition, 22 small-scale commercial layer farms in the neighbouring areas with respiratory disease problem were also investigated on request from the farmers. Pooled samples of oropharyngeal swabs from live birds or respiratory tissues from dead birds of the farm suffering from respiratory disease problem were tested for molecular detection of avian influenza virus (AIV), Newcastle disease virus (NDV), infectious bronchitis virus (IBV), infectious laryngotracheitis virus (ILTV), Mycoplasma gallisepticum and Avibacterium paragallinarum. A total of 110 farms (88 in the surveillance site and 22 in the neighbouring region) were investigated, and one or more respiratory pathogens were detected from 89 farms. AIV was detected in 57 farms often concurrently with other pathogens. Among these 57 farms, H5, H9, both H5 and H9 or non-H5 and non-H9 AIV were detected in 28, 9, 13 or 7 farms, respectively. Birds of most of the H5 AIV-positive farms did not present typical clinical signs or high mortality. Twenty such farms were observed longitudinally, which had only 1.05%-5.50% mortality but a marked drop in egg production. This widespread circulation of H5 AIV along with H9 AIV and other pathogens in small-scale commercial layer farms, often with low mortality, reaffirms the enzootic circulation of AIV in Bangladesh, which may escape syndromic surveillance focused on unusual mortality only. To reduce public health risks, strengthening of the control programme with comprehensive vaccination, enhanced biosecurity, improved surveillance and outbreak response is suggested.

Association of Biosecurity and Hygiene Practices with Environmental Contamination with Influenza A Viruses in Live Bird Markets, Bangladesh

In Bangladesh, live bird market environments are frequently contaminated with avian influenza viruses. Shop-level biosecurity practices might increase risk for environmental contamination. We sought to determine which shop-level biosecurity practices were associated with environmental contamination. We surveyed 800 poultry shops to describe biosecurity practices and collect environmental samples. Samples from 205 (26%) shops were positive for influenza A viral RNA, 108 (14%) for H9, and 60 (8%) for H5. Shops that slaughtered poultry, kept poultry overnight, remained open without rest days, had uneven muddy floors, held poultry on the floor, and housed sick and healthy poultry together were more frequently positive for influenza A viruses. Reported monthly cleaning seemed protective, but disinfection practices were not otherwise associated with influenza A virus detection. Slaughtering, keeping poultry overnight, weekly rest days, infrastructure, and disinfection practices could be targets for interventions to reduce environmental contamination.

Changes of avian influenza virus subtypes before and after vaccination in live poultry in Nanchang, China from 2016 to 2019

We investigated fluctuations in the detection rates of avian influenza virus (AIV) subtypes H5, H7, and H9 in live bird markets (LBMs) in Nanchang city, Chinese province Jiangxi, before and after the Chinese nationwide AIV vaccination campaign against highly pathogenic (HP) AIV subtype H5 and H7. Samples were tested for nucleic acid of type A avian influenza virus by real-time reverse transcription polymerase chain reaction technology. The H5, H7 and H9 subtypes of influenza viruses were further classified for the positive results. Based on the analysis of 2,119 samples collected from February 2016 to December 2019, we found that AIV subtypes H5, H7, H9 showed a seasonal pattern, and the positive rate of avian influenza tended to reach its peak in the colder season. The detection rate of AIV subtypes H5, H7, H9 of chickens (39.26%) was significantly higher than that of ducks (5.78%) and pigeons (4.31%). After vaccination, the positive rates of the H5 subtype (0.27%) and the H7 subtype (0.00%) decreased significantly, while the positive rate of the H9 subtype (29.95%) increased significantly. The H9 subtype has become the dominant subtype detected in live poultry and occupies a dominant position in the live bird market. This study showed that the government of China should establish measures for the long-term control of avian influenza.

Potential risk factors of avian influenza virus infection in asymptomatic commercial chicken flocks in selected areas of Bangladesh during 2019

Objective:

Avian influenza is a zoonotic disease with a pandemic potential that can infect avian and mammalian species, including humans. Studies aimed at investigating avian influenza virus (AIV) status in asymptomatic chickens and their shedding are uncommon in Bangladesh. Therefore, the current study aimed to examine the distribution of AIV subtypes in asymptomatic commercial chicken flocks and to identify the possible risk factors associated with this infection in two selected sub-districts of Bangladesh.

Materials and Methods:

A total of 582 oropharyngeal swabs were collected from 23 chicken farms during 2019 and evaluated for the presence of AIV and its subtypes by real-time reverse transcription PCR assays. Risk factors associated with AIV infection were analyzed from questionnaire data.

Results:

Overall, AIV prevalence was 7.73% (n = 45) with 7.39% and 7.92% in Dhamrai and Gazipur Sadar sub-districts, respectively. In AIV-positive samples, the prevalence of A/H5N1, A/H5N2, A/H9N1, and A/H9N2 was 31.11%, 28.89%, 6.67%, and 8.89%, respectively. None of the samples were positive for N6 and N8. The odds ratio (OR) of AIV infection was 1.15 in broiler versus layer and 2 in Sonali versus layer chickens. The OR was 1.95 for medium versus small, 2.6 for large versus small flock size, 1.5 for moderate versus good biosecurity, and 2.92 for poor versus good biosecurity practicing farms.

Conclusion:

The results demonstrated that A/H5N1, A/H5N2, A/H9N1, and A/H9N2 are circulating in asymptomatic chickens of selected areas. Strict farm biosecurity practices and avoiding higher flock density are recommended to prevent AIV spread in the study.

Patterns of Avian Influenza A (H5) and A (H9) virus infection in backyard, commercial broiler and layer chicken farms in Bangladesh

In order to control Highly Pathogenic Avian Influenza (HPAI) H5N1 and Low Pathogenic Avian Influenza (LPAI) H9N2 virus spread in endemically infected countries, a detailed understanding of infection patterns is required. We conducted cross-sectional studies in Bangladesh in 2016 and 2017, on 144 backyard, 106 broiler and 113 layer chicken farms. Although all sampled birds were negative for H5 virus by RT-PCR, H5 antibodies were detected in unvaccinated birds on all three farming systems. Higher H5 antibody prevalence was observed in ducks raised on backyard farms, 14.2% (95% CI: 10.0%-19.8%), compared to in-contact backyard chickens, 4.2% (95% CI: 2.8%-6.1%). The H5 antibody prevalence was lower in broiler chickens, 1.5% (95% CI: 0.9%-2.5%), compared to layer chickens, 7.8% (95% CI: 6.1%-9.8%). H9 viruses were detected by RT-PCR in 0.5% (95% CI: 0.2%-1.3%) and 0.6% (95% CI: 0.3%-1.5%) of broilers and layers, respectively, and in 0.2% (95% CI: 0.0%-1.2%) of backyard chickens. Backyard chickens and ducks showed similar H9 antibody prevalence, 16.0% (95% CI: 13.2%-19.2%) and 15.7% (95% CI: 11.3%-21.4%), which was higher compared to layers, 5.8% (95% CI: 4.3%-7.6%), and broilers, 1.5% (95% CI: 0.9%-2.5%). Over the course of a production cycle, H5 and H9 antibody prevalence increased with the age of backyard and layer chickens. Usually, multiple ducks within a flock were H5 antibody positive, in contrast to backyard chickens, broilers and layers where only individual birds within flocks developed H5 antibodies. Our findings highlight low virus circulation in healthy chickens of all production systems in Bangladesh, which is in contrast to high virus circulation reported from live bird markets. Data generated in this project can be used to adopt risk-based surveillance approaches in different chicken production systems in Bangladesh and to inform mathematical models exploring HPAI infection dynamics in poultry from the source of production.

Genetic diversity of the H5N1 viruses in live bird markets, Indonesia

Background

The live bird market (LBM) plays an important role in the dynamic evolution of the avian influenza H5N1 virus.

Objectives

The main objective of this study was to monitor the genetic diversity of the H5N1 viruses in LBMs in Indonesia.

Methods

Therefore, the disease surveillance was conducted in the area of Banten, West Java, Central Java, East Java, and Jakarta Province, Indonesia from 2014 to 2019. Subsequently, the genetic characterization of the H5N1 viruses was performed by sequencing all 8 segments of the viral genome.

Results

As a result, the H5N1 viruses were detected in most of LBMs in both bird' cloacal and environmental samples, in which about 35% of all samples were positive for influenza A and, subsequently, about 52% of these samples were positive for H5 subtyping. Based on the genetic analyses of 14 viruses isolated from LBMs, genetic diversities of the H5N1 viruses were identified including clades 2.1.3 and 2.3.2 as typical predominant groups as well as reassortant viruses between these 2 clades.

Conclusions

As a consequence, zoonotic transmission to humans in the market could be occurred from the exposure of infected birds and/or contaminated environments. Moreover, new virus variants could emerge from the LBM environment. Therefore, improving pandemic preparedness raised great concerns related to the zoonotic aspect of new influenza variants because of its high adaptivity and efficiency for human infection.

Qualitative risk assessment of transmission pathways of highly pathogenic avian influenza (HPAI) virus at live poultry markets in Dhaka city, Bangladesh

Analysis of environmental samples obtained from the Live Poultry Markets (LPMs) of Dhaka City, Bangladesh, has revealed that the highest degree of prevalence of highly pathogenic avian influenza A (HPAI, H5N1), besides other subtypes of the LPAI virus, poses the plausible risk of transmission of these viruses between human and poultry species. The present study was conducted using the OIE risk analysis framework to assess the risk level of each pathway successively. The estimated risk parameters were integrated towards to obtain the overall risk level for each specific HPAI transmission pathway using the matrix adapted by Cristobel Zepeda accompanying other expert consultations. The relevant data obtained from published and unpublished sources, together with survey data of field observations, were used to formulate and confirm the risk pathways and their associated risks. The results revealed that the risk of the release of the HPAI virus was medium when exposure was high. Additionally, the consequence would be considered very high with a medium degree of uncertainty for all parameters. Ultimately, the overall risk for transmission was estimated as medium with a medium degree of uncertainty. The findings of this study reveal that there is a significant threat that HPAI virus transmission could occur among poultry and humans and effectively sustain within the environment of the LPMs. Our findings are primarily focused on public health considerations, the hygienic slaughter of poultry and the relevant cleaning and sanitation practices conducted in the LPMs to support evidence-based decision-making processes. The findings of the study have the potential to be used to formulate effective risk reduction measures and can be further adapted in low-resource settings without major infrastructural changes required of the LPMs. All of which would reduce the risk of HPAI virus release and further lessen the degree of exposure and transmission in established LPMs.

Genetic evolution and transmission dynamics of clade 2.3.2.1a highly pathogenic avian influenza A/H5N1 viruses in Bangladesh

Asian lineage A/H5N1 highly pathogenic avian influenza viruses (HPAIVs) have been responsible for continuous outbreaks in Bangladesh since 2007. Although clades 2.2.2 and 2.3.4.2 HPAIVs have disappeared since poultry vaccination was introduced in 2012, clade 2.3.2.1a viruses have continued to be detected in Bangladesh. In this study, we identified A/H9N2 (n = 15), A/H5N1 (n = 19), and A/H5N1-A/H9N2 (n = 18) mixed viruses from live bird markets, chicken farms, and wild house crows (Corvus splendens) in Bangladesh from 2016 to 2018. We analyzed the genetic sequences of the H5 HPAIVs, to better understand the evolutionary history of clade 2.3.2.1a viruses in Bangladesh. Although seven HA genetic subgroups (B1-B7) and six genotypes (G1, G1.1, G1.2, G2, G2.1, and G2.2) have been identified in Bangladesh, only subgroup B7 and genotypes G2, G2.1, and G2.2 were detected after 2016. The replacement of G1 genotype by G2 in Bangladesh was possibly due to vaccination and viral competition in duck populations. Initially, genetic diversity decreased after introduction of vaccination in 2012, but in 2015, genetic diversity increased and was associated with the emergence of genotype G2. Our phylodynamic analysis suggests that domestic Anseriformes, including ducks and geese, may have played a major role in persistence, spread, evolution, and genotype replacement of clade 2.3.2.1a HPAIVs in Bangladesh. Thus, improvements in biosecurity and monitoring of domestic Anseriformes are needed for more effective control of HPAI in Bangladesh.

Avian Influenza Virus Detection Rates in Poultry and Environment at Live Poultry Markets, Guangdong, China

We report the use of environmental samples to assess avian influenza virus activity in chickens at live poultry markets in China. Results of environmental and chicken samples correlate moderately well. However, collection of multiple environmental samples from holding, processing, and selling areas is recommended to detect viruses expected to have low prevalence.

The evolution and genetic diversity of avian influenza A(H9N2) viruses in Cambodia, 2015 - 2016

Low pathogenic A(H9N2) subtype avian influenza viruses (AIVs) were originally detected in Cambodian poultry in 2013, and now circulate endemically. We sequenced and characterised 64 A(H9N2) AIVs detected in Cambodian poultry (chickens and ducks) from January 2015 to May 2016. All A(H9) viruses collected in 2015 and 2016 belonged to a new BJ/94-like h9-4.2.5 sub-lineage that emerged in the region during or after 2013, and was distinct to previously detected Cambodian viruses. Overall, there was a reduction of genetic diversity of H9N2 since 2013, however two genotypes were detected in circulation, P and V, with extensive reassortment between the viruses. Phylogenetic analysis showed a close relationship between A(H9N2) AIVs detected in Cambodian and Vietnamese poultry, highlighting cross-border trade/movement of live, domestic poultry between the countries. Wild birds may also play a role in A(H9N2) transmission in the region. Some genes of the Cambodian isolates frequently clustered with zoonotic A(H7N9), A(H9N2) and A(H10N8) viruses, suggesting a common ecology. Molecular analysis showed 100% of viruses contained the hemagglutinin (HA) Q226L substitution, which favours mammalian receptor type binding. All viruses were susceptible to the neuraminidase inhibitor antivirals; however, 41% contained the matrix (M2) S31N substitution associated with resistance to adamantanes. Overall, Cambodian A(H9N2) viruses possessed factors known to increase zoonotic potential, and therefore their evolution should be continually monitored.

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.

Poultry trading behaviours in Vietnamese live bird markets as risk factors for avian influenza infection in chickens

Vietnamese poultry are host to co‐circulating subtypes of avian influenza viruses, including H5N1 and H9N2, which pose a great risk to poultry productivity and to human health. AIVs circulate throughout the poultry trade network in Vietnam, with live bird markets being an integral component to this network. Traders at LBMs exhibit a variety of trading practices, which may influence the transmission of AIVs. We identified trading practices that impacted on AIV prevalence in chickens marketed in northern Vietnamese LBMs. We generated sequencing data for 31 H9N2 and two H5N6 viruses. Viruses isolated in the same LBM or from chickens sourced from the same province were genetically closer than viruses isolated in different LBMs or from chickens sourced in different provinces. The position of a vendor in the trading network impacted on their odds of having AIV‐infected chickens. Being a retailer and purchasing chickens from middlemen was associated with increased odds of infection, whereas odds decreased if vendors purchased chickens directly from large farms. Odds of infection were also higher for vendors having a greater volume of ducks unsold per day. These results indicate how the spread of AIVs is influenced by the structure of the live poultry trading network.

Prevalence and molecular characterization of infectious bronchitis virus isolated from chicken in Bangladesh

Aim:

The present study was aimed to determine the prevalence of infectious bronchitis virus (IBV) as well as virus isolation, identification, and molecular characterization of various strains circulating in Bangladesh.

Materials and Methods:

A total of 371 swabs and organ samples were collected from four types of chicken including layer, Sonali (local), broiler, and broiler breeder under eight districts (Rangpur, Bogura, Tangail, Dhaka, Gazipur, Mymensingh, Jamalpur, and Cumilla) during 2014-2016 in Bangladesh.

Results:

Out of 371 samples, 65 samples were positive in reverse transcriptase polymerase chain reaction (RT-PCR) for molecular identification of IBV. The overall prevalence was 17.52% recorded and among the selected types of chicken, the highest prevalence of IBV was found in layer that was 42.22% followed by 17.24% in Sonali, 14.93% in broiler breeder, and lowest prevalence was 11.94% in broiler chicken, respectively. Moreover, the prevalence of IBV was recorded highest in aged chicken at 41-60 weeks, which was 54.55% in layer, 27.27% in Sonali, and, afterward, 14.68% was found in broiler breeder, respectively. Frequency of IBV more frequently in winter (22.67%) followed by rainy (15.87%) and summer season (11.58%). The highest prevalence of IBV was found Tangail district (41.67%) followed by Mymensingh (24.42%), Gazipur (19.32%), Dhaka (15.38%), Jamalpur (16.67%), Bogura (13.68%), Cumilla (5.88%), and Rangpur (9.26%), respectively. Samples that were found high positive in IBV RT-PCR (Ct value below 30) were subjected to inoculation into chicken egg embryo to observe characteristic changes in chicken embryo. Swabs and organ samples were processed and passaged in 9-day-old embryonated chicken eggs through allantoic cavity route. IBV virus suspected samples inoculated into chicken egg embryos after 3-5 passages showed dwarfing and curling of the embryos which are characteristic lesions of IBV. Allantoic fluid was collected from all inoculated eggs and performed partial sequencing of S1 gene for three isolates. After sequencing, the phylogenetic tree was constructed from the nucleotide sequences of IBV isolates. Two of the isolates are 4/91 IBV and another one matched with QX-like IBV.

Conclusion:

The results revealed that the three isolates from different places in Bangladesh were identified for the 1^st time as which will help for IBV control strategy.

Comparison of Avian Influenza Virus Contamination in the Environment Before and After Massive Poultry H5/H7 Vaccination in Zhejiang Province, China

Background

Information regarding comparison of the environmental prevalence of avian influenza virus (AIVs), before and after massive poultry vaccinations, is limited. Our study aimed to detect differences in the prevalence of AIVs type A and subtypes H5, H7, and H9 before and after the September 2017 massive poultry vaccination, across different sampling places and types.

Methods

We collected 55 130 environmental samples from 11 cities in Zhejiang Province (China) between March 2013 and December 2018. Multivariate logistic regression analyses were conducted to determine the prevalence of AIV type A and subtypes H5, H7, and H9 across different sampling places and types, before and after massive poultry vaccination.

Results

After the vaccination, contamination risk of AIV type A (adjusted odds ratio [aOR] = 1.08; 95% confidence interval [CI], 1.03–1.14) and subtype H9 (aOR = 1.58; 95% CI, 1.48–1.68) increased, and that of subtype H7 (aOR = 0.12; 95% CI, 0.10–0.14) decreased. Statistically significant decreased risk for H7 subtype contamination and increased risk for H9 subtype contamination were observed in backyard poultry flocks, live poultry markets, and slaughtering/processing plants. Swabs from poultry cages and slaughtering tables showed a statistically significant increased risk for H5 subtype contamination. The prevalence of H7 subtype decreased statistically significantly, whereas that of H9 subtype increased across the 5 sample types (poultry cages swabs, slaughtering table swabs, poultry feces, poultry drinking water, and poultry sewage).

Conclusions

Despite the sharp decrease in H7 subtype prevalence, reduction measures for AIV circulation are still imperative, given the high type A prevalence and the increase in H9 subtype contamination across different sampling places and types.