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

Regulations, biosecurity measures, and impact of COVID-19: A comprehensive mixed method study in traditional wet and live animal markets in Bangladesh

Background

Traditional wet and live animal markets (TWLAMs) offer fresh vegetables, meat, fish, and live animals to consumers at affordable prices. The daily operation of TWLAMs is crucial for supplying safe food by controlling and preventing contamination from food-borne pathogens.

Objectives

A cross-sectional study was conducted in 10 TWLAMs to collect and assess data on market regulations, biosecurity measures, and the impact of COVID-19 on food supply and livelihoods.

Methods

We interviewed 40 key informants and performed on-site observations. Additionally, we organized a workshop with different stakeholders including experts in human health, animal health, food safety, zoonotic diseases, agriculture, consumer rights, and market regulations.

Results

Among the 10 surveyed TWLAMs, five (50 %) were governed by the City Corporation, six (60 %) had written operational guidelines, while 40 % were unaware of any government regulations. Most markets (80 %, n = 8) lacked direct water supply lines for their shops, and 50 % had no functional drainage systems. A majority (55 %, n = 22) of the key informants reported not seeing any food inspectors at the market within the last three months. Only 60 % (n = 24) believed that live animals could transmit diseases to humans within wet markets. While shop-level cleaning was regularly conducted, cleaning of the entire market was infrequent. COVID-19 had both negative and positive impacts on TWLAM. The most common negative effects were job losses (65 %) and increased living expenses (67 %), while COVID-19 led to improvements in market hygiene (100 %), personal hygiene (100 %), and adherence to social distancing (100 %). No permanent closures or bans on animal trading were reported in TWLAM during the COVID-19 pandemic. All workshop participants (n = 55) indicated that shifting from live animal trading to processed animal products would be challenging due to cultural norms and practices.

Conclusions

Despite many challenges and shortcomings, a unique operational guideline could help ensure the supply of safe food to consumers. Financial incentives, certification, training, and regular monitoring can improve practices associated with food safety.

Epidemiology and evolutionary dynamics of H9N2 avian influenza virus in Bangladesh

Low pathogenicity avian influenza (LPAI) H9N2 has been enzootic in Bangladeshi poultry since 2006. H9N2 outbreaks can decrease egg production and growth and pose a risk to human health. The role of avian hosts in the persistence, evolution, and dispersion of H9N2 is poorly understood in Bangladesh. Hence, this study unveils the intricate role of major host species in virus maintenance and evolution and the temporal and seasonal patterns of H9N2 in Bangladesh from 2006 to 2023. Multinomial logistic regression analysis indicated that the circulation of H9N2 in different species and interfaces is significantly influenced by the seasons. Bayesian phylogenetic analysis of H9N2 sequences in Bangladesh revealed two distinct lineages: G1 and Eurasian. The G1 lineage split into two clusters, coexisting until 2019, at which point only one cluster persisted. Bayesian phylodynamic analysis of G1 lineage unveiled frequent bidirectional viral transitions among ducks, chickens, and quails. Chickens might be a pivotal source of H9N2 in Bangladesh, with a higher number of viral transitions from chickens to ducks and quails. Quails appear to acquire most of their viral transitions from chickens rather than ducks, suggesting that quail epizootics are primarily triggered by spillover events from chickens. Our results suggest viral circulation in commercial chickens despite vaccination. The vaccination approach should be revised, assess vaccine efficacy, and extension of vaccination to backyard chickens and quails.

Clustering broiler farmers based on their behavioural differences towards biosecurity to prevent highly pathogenic avian influenza

Highly pathogenic avian influenza (HPAI) is an important zoonotic disease. The study aims to identify farmer behaviour types to inform the design of behaviour change programmes for mitigating the transmission of HPAI. Therefore, the study utilised multivariate statistical analysis for gaining a better understanding of the relationships among farmers' 30 biosecurity behaviours, the risk of HPAI infection, and distinct features of commercial broiler farmers, which is different from using simple and few binary biosecurity measures. Convenience sampling was used to collect data from 303 Taiwan's farmers among which 40 farmers (13.2%) self-reported having had a HPAI outbreak in the study year while 16 farmers (5.3%) self-reported having had a HPAI outbreak in the past two years. Using categorical principal components analysis and a two-stage cluster analysis, four farmer clusters were identified with distinct features: 1)'Reserved' (4.6%) tended to choose 'No idea' for answering specific questions about HPAI; 2)'Secure' (76.3%) had a higher biosecurity status than the other farms; 3) 'Jeopardised' (16.8%) had a lower biosecurity status than the other farms; 4) 'No-response' (2.3%) tended to skip specific questions about HPAI. The biosecurity status of the 'Reserved' and 'No-response' clusters was undetermined, placing these farms at risk of HPAI infection. Compared to the 'Secure' cluster, the 'Jeopardised' cluster exhibited higher odds of self-reported HPAI in the study year (OR: 2.61, 95% CI: 1.22-5.58) and in the past two years (OR: 4.28, 95% CI: 1.39-13.19). Additionally, the 'Jeopardised' cluster showed increased odds of HPAI recurrence (OR: 4.01, 95% CI: 1.41-11.43). Our study demonstrates that inadequate biosecurity practices can elevate the occurrence or recurrence of HPAI outbreaks. The findings underscore the importance of distinguishing between these clusters to accurately assess the risk of HPAI infection across farms. Furthermore, understanding farmers' behaviours can inform the development of strategies aimed at behaviour change among farmers.

Farm biosecurity practices affecting avian influenza virus circulation in commercial chicken farms in Bangladesh

Avian influenza virus (AIV) is of major concern to livestock, wildlife, and human health. In many countries in the world, including Bangladesh, AIV is endemic in poultry, requiring improving biosecurity. In Bangladesh, we investigated how variation in biosecurity practices in commercial chicken farms affected their AIV infection status to help guide AIV mitigation strategies. We collected pooled fecal swabs from 225 farms and tested the samples for the AIV matrix gene followed by H5, H7, and H9 subtyping using rRT-PCR. We found that 39.6% of chicken farms were AIV positive, with 13% and 14% being positive for subtypes H5 and H9, respectively. Using a generalized linear mixed effects model, we identified as many as 12 significant AIV risk factors. Two major factors promoting AIV risk that cannot be easily addressed in the short term were farm size and the proximity of the farm to a live bird market. However, the other ten significant determinants of AIV risk can be more readily addressed, of which the most important ones were limiting access by visitors (reducing predicted AIV risk from 42 to 6%), isolation and treatment of sick birds (42 to 7%), prohibiting access of vehicles to poultry sheds (38 to 8%), improving hand hygiene (from 42 to 9%), not sharing farm workers across farms (37 to 8%), and limiting access by wild birds to poultry sheds (37 to 8%). Our findings can be applied to developing practical and cost-effective measures that significantly decrease the prevalence of AIV in chicken farms. Notably, in settings with limited resources, such as Bangladesh, these measures can help governments strengthen biosecurity practices in their poultry industry to limit and possibly prevent the spread of AIV.

Association of biosecurity and hygiene practices with avian influenza A/H5 and A/H9 virus infections in turkey farms

High pathogenicity avian influenza (HPAI) H5N1 outbreaks pose a significant threat to the health of livestock, wildlife, and humans. Avian influenza viruses (AIVs) are enzootic in poultry in many countries, including Bangladesh, necessitating improved farm biosecurity measures. However, the comprehension of biosecurity and hygiene practices, as well as the infection of AIV in turkey farms, are poorly understood in Bangladesh. Therefore, we conducted this study to determine the prevalence of AIV subtypes and their association with biosecurity and hygiene practices in turkey farms. We collected oropharyngeal and cloacal swabs from individual turkeys from 197 farms across 9 districts in Bangladesh from March to August 2019. We tested the swab 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 found 24.68% (95% CI:21.54-28.04) of turkey samples were AIV positive, followed by 5.95% (95% CI: 4.33-7.97) for H5, 6.81% (95% CI: 5.06-8.93) for H9 subtype and no A/H7 was found. Using a generalized linear mixed model, we determined 10 significant risk factors associated with AIV circulation in turkey farms. We found that the absence of sick turkeys, the presence of footbaths, the absence of nearby poultry farms, concrete flooring, and the avoidance of mixing newly purchased turkeys with existing stock can substantially reduce the risk of AIV circulation in turkey farms (odds ratio ranging from 0.02 to 0.08). Furthermore, the absence of nearby live bird markets, limiting wild bird access, no visitor access, improved floor cleaning frequency, and equipment disinfection practices also had a substantial impact on lowering the AIV risk in the farms (odds ratio ranging from 0.10 to 0.13). The results of our study underscore the importance of implementing feasible and cost-effective biosecurity measures aimed at reducing AIV transmission in turkey farms. Particularly in resource-constrained environments such as Bangladesh, such findings might assist governmental entities in enhancing biosecurity protocols within their poultry sector, hence mitigating and potentially averting the transmission of AIV and spillover to humans.

The role of vaccination and environmental factors on outbreaks of high pathogenicity avian influenza H5N1 in Bangladesh

High Pathogenicity Avian Influenza (HPAI) H5N1 outbreaks continue to wreak havoc on the global poultry industry and threaten the health of wild bird populations, with sporadic spillover in humans and other mammals, resulting in widespread calls to vaccinate poultry. Bangladesh has been vaccinating poultry since 2012, presenting a prime opportunity to study the effects of vaccination on HPAI H5N1circulation in both poultry and wild birds. We investigated the efficacy of vaccinating commercial poultry against HPAI H5N1 along with climatic and socio-economic factors considered potential drivers of HPAI H5N1 outbreak risk in Bangladesh. Using a multivariate modeling approach, we estimated that the rate of outbreaks was 18 times higher before compared to after vaccination, with winter months having a three times higher chance of outbreaks than summer months. Variables resulting in small but significant increases in outbreak rate were relatively low ambient temperatures for the time of year, literacy rate, chicken and duck density, crop density, and presence of highways; this may be attributable to low temperatures supporting viral survival outside the host, higher literacy driving reporting rate, density of the host reservoir, and spread of the virus through increased connectivity. Despite the substantial impact of vaccination on outbreaks, we note that HPAI H5N1 is still enzootic in Bangladesh; vaccinated poultry flocks have high rates of H5N1 prevalence, and spillover to wild birds has increased. Vaccination in Bangladesh thus bears the risk of supporting "silent spread," where the vaccine only provides protection against disease and not also infection. Our findings underscore that poultry vaccination can be part of holistic HPAI mitigation strategies when accompanied by monitoring to avoid silent spread.