ABSTRACT
The prevalence of avian influenza viruses is commonly found to increase dramatically as birds are transported from farms to live bird markets. Viral transmission dynamics along marketing chains are, however, poorly understood. To address this gap, we implemented a controlled field experiment altering chicken supply to a live bird market in Chattogram, Bangladesh. Broilers and backyard chickens traded along altered (intervention) and conventional (control) marketing chains were tested for avian influenza viruses at different time points. Upon arrival at the live bird market, the odds of detecting avian influenza viruses did not differ between control and intervention groups. However, 12â¯h later, intervention group odds were lower, particularly for broilers, indicating that viral shedding in live bird markets resulted partly from infections occurring during transport and trade. Curtailing avian influenza virus prevalence in live bird markets requires mitigating risk in marketing chain nodes preceding chickens' delivery at live bird markets.
Subject(s)
Chickens , Influenza in Birds , Poultry Diseases , Animals , Influenza in Birds/epidemiology , Influenza in Birds/virology , Bangladesh/epidemiology , Poultry Diseases/virology , Poultry Diseases/epidemiology , Poultry Diseases/transmission , Poultry Diseases/prevention & control , Prevalence , Influenza A virus/isolation & purification , Transportation , Animal Husbandry/methods , Virus Shedding , Marketing , CommerceABSTRACT
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.
Subject(s)
Chickens , Influenza A Virus, H9N2 Subtype , Influenza in Birds , Animals , Influenza A Virus, H9N2 Subtype/isolation & purification , Influenza A Virus, H9N2 Subtype/immunology , Influenza in Birds/transmission , Influenza in Birds/epidemiology , Influenza in Birds/virology , Chickens/virology , Bangladesh/epidemiology , Poultry Diseases/transmission , Poultry Diseases/virology , Poultry Diseases/epidemiology , Models, BiologicalABSTRACT
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.
Subject(s)
Epidemics , Influenza in Birds , Animals , Poultry , Chickens , Influenza in Birds/epidemiology , Zoonoses/epidemiologyABSTRACT
BACKGROUND: Factors influencing parasitosis in cattle in Bangladesh remain inadequately explored, necessitating a comprehensive investigation for interventions and sustainable livestock farming. OBJECTIVES: We conducted this study to estimate the prevalence and distribution of gastrointestinal parasites, exploring their intricate relationship with farm management practices across a spectrum of small-, medium-, and large-scale commercial farms. METHODS: We conducted this study in the Chattogram district of Bangladesh. We collected a total of 189 freshly voided faecal samples from different farms. We recorded the age, breed, milking status, sex, body condition score, and anthelmintic use history of the sampled animals. We processed the samples using the direct smear method, with the identification of one egg per sample being considered positive. RESULTS: We estimated the prevalence of gastrointestinal parasite infection in large-scale (52.1%), medium-scale (54.5%), and small-scale farms (70.0%), with statistically significant differences (p ≤ 0.05). Both pregnant and lactating cows, as well as indigenous cattle, were more likely to have gastrointestinal parasites (p ≤ 0.05). The predominant parasites across farms of all sizes were trematodes (Paramphistomum spp. and Schistosomas spp.) and protozoa (Balantidium coli and Coccidia spp.). CONCLUSION: Poor farm management practices, such as no pasture management and inadequate deworming regimens, may contribute to the elevated prevalence and infection load observed on small-scale farms. The increased parasitosis in previously dewormed animals can be attributed to the development of anthelmintic resistance against gastrointestinal parasites. Implementing proper and effective deworming strategies is crucial to preventing gastrointestinal parasitosis and mitigating the risk of anthelmintic resistance.
Subject(s)
Anthelmintics , Cattle Diseases , Gastrointestinal Diseases , Intestinal Diseases, Parasitic , Female , Animals , Cattle , Lactation , Bangladesh/epidemiology , Anthelmintics/therapeutic use , Intestinal Diseases, Parasitic/epidemiology , Intestinal Diseases, Parasitic/veterinary , Intestinal Diseases, Parasitic/parasitology , Gastrointestinal Diseases/epidemiology , Gastrointestinal Diseases/veterinary , Cattle Diseases/parasitologyABSTRACT
Bangladesh's commercial poultry production is growing rapidly, including the commercial processing of poultry. This expansion of poultry processing plants is fueled by the belief that this sub-sector provides safer food and has less food-borne disease risks compared to traditional live bird markets (LBMs). The purpose of this study is to describe Bangladesh's dressed and processed poultry production and distribution network (PDN), identify what and where quality control occurs, and suggest where improvements could be made. Engaging with PDN for dressed and processed poultry, we used in-depth interviews with key informants to identify the stakeholders involved and their connections with other poultry PDNs. In addition, we mapped out the supply and distribution of dressed and processed poultry and quality control processes occurring throughout the network. We argue that dressed and processed poultry PDNs are closely connected with traditional PDNs such as LBMs, with multiple crossover points between them. Also, there is a lack of consistency in quality control testing and a lack of meat traceability. Consequently, perceptions of dressed and processed poultry being safer than birds from LBMs needs to be treated with caution. Otherwise, unsubstantiated consumer confidence in dressed poultry may inadvertently increase the risk of food-borne diseases from these products.
Subject(s)
Influenza in Birds , Poultry Products , Animals , Bangladesh , Poultry , Food SafetyABSTRACT
Subclinical mastitis (SCM) in water buffalo is responsible for reduced milk yield and quality. This cross-sectional study was carried out to a) estimate the prevalence of SCM, b) identify risk factors associated with SCM, and c) identify farm-level risk factors associated with bulk milk somatic cell count (BMSCC). The buffalo farms included in this study represented five rearing systems: free-range, semi-free-range, household, semi-intensive, and intensive, providing a total of 3491 functional quarters of 880 lactating buffalo on 248 farms. The California mastitis test score was used to identify SCM. Bulk milk samples (n = 242) were used for farm-level BMSCC. Quarter and buffalo-level risk factors for SCM were measured using questionnaires and observations. The overall SCM prevalence was high at 27.9% at the quarter-level (25th and 75th percentiles: 8.3% and 41.7%) and 51.5% at buffalo-level (25th and 75th percentiles: 33.3% and 66.7%). The geometric mean BMSCC was 217,000 cells/mL of milk (ranging from 36,000-1,213,000 cells/mL), which is low on average, but some farms could improve substantially. The buffalo rearing system, udder location (left versus right), teat shape, udder asymmetry, number of milkers, and having a quarantine facility were associated with buffalo udder health. Our findings suggest that mainly using free-range rearing systems may help decrease the prevalence of SCM primarily by employing buffalo breeding and better farm biosecurity, and udder health control strategies can be designed based on our findings.
Subject(s)
Bison , Cattle Diseases , Mastitis, Bovine , Cattle , Animals , Female , Lactation , Buffaloes , Prevalence , Cross-Sectional Studies , Bangladesh/epidemiology , Mastitis, Bovine/epidemiology , Dairying , Milk , Risk Factors , Mammary Glands, Animal , Cell Count/veterinaryABSTRACT
This study aimed to review the existing communication systems between the universities, placement providers, and students during the DVM final year work-based learning (WBL) program in Bangladesh. The intention was to identify what factors impact the effectiveness of the communication system and to explore ways to enhance communication to better support the program. A questionnaire was used to collect details about the WBL program and the communication systems from all universities in Bangladesh. The questionnaire was completed on paper at a meeting of the National Veterinary Dean Council and online with a member of each university's WBL coordination team. A summary of the current WBL programs in Bangladesh was produced. Focus group discussions were used to collect more detailed information about the communication systems and were held via Zoom with recent graduates (n = 16) and placement providers (n = 7). Effective means of communication between all stakeholders were identified as an initial letter, phone calls, and spot visits by teachers. However, the frequency of formal communication before and during placements was variable and the ways of providing feedback on the communication systems were insufficient. These issues sometimes undermined the student learning experience. Suggestions for improvements included increased resourcing, greater use of online communication systems, and a national committee to oversee WBL. Other ways to motivate placement providers included a better honorarium and continuing education courses. The results suggest that existing communication systems for veterinary WBL in Bangladesh are not completely satisfactory. Measures are needed to improve communication to optimize the student learning experience and capitalize on the many benefits of the WBL program for all stakeholders.
ABSTRACT
Veterinary clinical skills training is evolving rapidly around the world and there is increasing interest in Bangladesh in opening clinical skills laboratories and using models in teaching. The first clinical skills laboratory was opened at Chattogram Veterinary and Animal Sciences University in 2019. The current study aimed to identify the most important clinical skills for veterinarians in Bangladesh to inform the further development of clinical skills laboratories and ensure resources are deployed effectively and efficiently. Lists of clinical skills were collated from the literature, national and international accreditation standards, and regional syllabi. The list was refined through local consultation, focused on farm and pet animals, and was disseminated via an online survey to veterinarians and final-year students who were asked to rate the level of importance of each skill for a new graduate. The survey was completed by 215 veterinarians and 115 students. A ranked list was generated with injection techniques, animal handling, clinical examination, and basic surgical skills among the most important. Some techniques requiring specific equipment and some advanced surgical procedures were considered less important. As a result of the study, the most important clinical skills for a new graduate in Bangladesh have been identified for the first time. The results will inform the development of models, the use of clinical skills laboratories, and the design of clinical skills courses for veterinary training. Our approach of drawing upon existing lists followed by local stakeholders consultation is recommended to others to ensure clinical skills teaching is regionally relevant.
ABSTRACT
A systematic review was conducted to summarize and synthesize the existing research on poultry farmers' knowledge, practices, and awareness regarding antimicrobial use (AMU) and antimicrobial resistance (AMR). It was undertaken by systematically searching databases, screening and characterizing relevant studies, extracting data, and evaluating the risk of bias. The outcomes were stratified into several subgroups, and pooled prevalence of each subgroup was calculated using a random-effect meta-analysis. Meta-regression was used for selected outcomes to further investigate the potential sources of heterogeneity across studies. Poultry farmers had knowledge and practice gaps on antimicrobial use. While most (65%; 95% CI: 50%-80%) used antimicrobials on poultry for therapeutic purposes, a portion used them to prevent disease (45%; 95% CI: 34%-55%) or boost growth (29%; 95% CI: 13%-46%) and productivity (20%; 95% CI: 6%-34%). 60% (95% CI: 50%-69%) of farmers approached veterinarians for antimicrobial advice, although many consulted drug sellers and fellow farmers. Insufficient antimicrobial residue knowledge (45%; 95% CI: 29%-62%), as well as inadequate awareness and faulty practice on withdrawal periods, were identified. Only 43% (95% CI: 34%-53%) were knowledgeable about AMR. Around half of farmers understood AMR's impacts on poultry, human health, and the environment. Meta-regression demonstrated that the source of heterogeneity for therapeutic antimicrobial use was the type of poultry farmers sampled and their educational qualifications; geographical region was significantly associated with antimicrobial usage based on farmers' experience; and the country's economic state was correlated with farmers' understanding of antimicrobial residue. This study recommends implementing legislation for judicious antimicrobial use, and farmer awareness campaigns to reinforce knowledge about prudent AMU and AMR.
Subject(s)
Anti-Bacterial Agents , Anti-Infective Agents , Humans , Animals , Anti-Bacterial Agents/therapeutic use , Farmers , Poultry , Health Knowledge, Attitudes, Practice , Anti-Infective Agents/therapeutic useABSTRACT
Adapting the Social Cognitive Theory framework, we conducted a cross-sectional study on 137 commercial chicken farms in Bangladesh to investigate factors influencing the behaviour of farmers towards the application of antimicrobials to their birds. Almost all farmers used antimicrobials to treat poultry diseases, while 38.6% also were using them to promote healthy growth of chickens and 10.2% to increase egg production or improve meat quality. Using Structural Equation Modeling (SEM), we identified that inappropriate usage of antimicrobials (behaviour) was strongly driven by farmers' short-term goals to maintain the health of their chickens in a production cycle (ß = 0.813, p = 0.029), rather than long-term concerns. Farmers' perception about their ability to control antimicrobial administration based on their skills and opportunities (self-efficacy) marginally influenced the short-term goals of antimicrobial usage (ß = 0.301, p = 0.073). The results of this study can be used to develop targeted education programs for farmers, to reduce the application of antimicrobials in their poultry flocks.
Subject(s)
Anti-Infective Agents , Chickens , Animals , Humans , Farmers , Bangladesh , Cross-Sectional Studies , CognitionABSTRACT
Irrational and inappropriate use of antibiotics in commercial chicken production can contribute to the development of antimicrobial resistance. We aimed to assess antibiotic usage in commercial chicken production in Bangladesh, and identify factors associated with this practice. We conducted a large-scale cross-sectional study to collect information on antibiotic usage in commercial chickens from January to May 2021. Structured interviews were conducted with 288 broiler, 288 layer and 192 Sonali (locally-produced cross-bred) farmers in 20 sub-districts across Bangladesh. The frequency of antibiotic usage, the types of antibiotics and purpose of usage were estimated for each production type. Adjusted odds ratios (aOR) were calculated to measure the association between antibiotic usage and factors related to the characteristics of the farms and farmers using multivariable logistic regression models. The proportion of farms, irrespective of their production type, reporting usage of antibiotics in the 24 hours preceding the interview was 41% (n = 314, 95% CI: 37-44%). Forty-five percent (n = 344, 41-48%) reported antibiotic usage in the last 72 hours, 86% (n = 658, 83-88%) in the last 14 days, and almost all farms, 98% (n = 753, 97-99%), had used antibiotics since the start of their production cycle. Use of antibiotics in the 24 hours preceding an interview was more frequently reported in broiler (OR 1.91, 95% CI: 1.36-2.69) and Sonali (OR 1.94, 95% CI: 1.33-2.33) than layer farms. Oxytetracycline (23-31%, depending on production type), doxycycline (18-25%), ciprofloxacin (16-26%) and amoxicillin (16-44%) were the most frequently used antibiotics. Antibiotics were reported to be used for both treatment and prophylactic purposes on most farms (57-67%). Usage of antibiotics in the 24h preceding an interview was significantly associated with the occurrence of any illnesses in chickens (aOR broiler: 41.22 [95% CI:13.63-124.62], layer: aOR 36.45[9.52-139.43], Sonali: aOR 28.47[4.97-162.97]). Antibiotic usage was mainly advised by veterinary practitioners (45-71%, depending on production type), followed by feed dealers (21-40%) and farmers (7-13%). Improvement of chicken health through good farming practices along with changes in key stakeholders (feed dealers and practitioners) attitudes towards antibiotic recommendations to farmers, may help to reduce the levels of antibiotic usage and thus contribute to mitigate antimicrobial resistance.
Subject(s)
Chickens , Oxytetracycline , Amoxicillin , Animals , Anti-Bacterial Agents/therapeutic use , Bangladesh , Ciprofloxacin , Cross-Sectional Studies , DoxycyclineABSTRACT
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.
Subject(s)
Influenza A virus , Influenza in Birds , Poultry Diseases , Animals , Humans , Poultry , Influenza in Birds/epidemiology , Bangladesh/epidemiology , Cross-Sectional Studies , Phylogeny , Influenza A virus/genetics , Chickens , Ducks , Poultry Diseases/epidemiologyABSTRACT
The Coronavirus Disease 2019 (COVID-19) spread rapidly from China to most other countries around the world in early 2020 killing millions of people. To prevent virus spread, world governments implemented a variety of response measures. This paper's objectives were to discuss the country's adopted measures to combat the virus through June 2020, identify gaps in the measures' effectiveness, and offer possible mitigations to those gaps. The measures taken included screening device deployment across international air and land ports, flight suspensions and closures from COVID-19 affected countries, and declaration and extension of a national public holiday (equivalent to lockdowns in other countries). Identified gaps were test kit, PPE, ICU beds, and ventilator shortages, limited public awareness, and insufficient coordination and collaboration among national and international partners. Proper and timely risk mapping, preparedness, communication, coordination, and collaboration among governments and organizations, and public awareness and engagement would have provided sufficient COVID-19 mitigation in Bangladesh.
Subject(s)
COVID-19 , Bangladesh/epidemiology , COVID-19/prevention & control , China , Communicable Disease Control , Humans , SuspensionsABSTRACT
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.
Subject(s)
Influenza in Birds , Animals , Animals, Wild , Bangladesh/epidemiology , Chickens , Cross-Sectional Studies , Farms , Poultry , Risk FactorsABSTRACT
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.
ABSTRACT
Mastitis is a major production disease, causing significant economic losses for dairy farmers in South-Asian countries, as well as other parts of the world. Udder health control programs (UHCP) have been established in developed countries as an effective strategy for mastitis control but have not yet been introduced in South-Asian low-income countries like Bangladesh, India, Pakistan, and Sri Lanka. To launch UHCP successfully in dairy herds in South-Asia, it is important to know the current prevalence and risk factors for subclinical mastitis (SCM). Therefore, a narrative literature review was conducted with the aim to describe the dairy sector, the prevalence of SCM and its causal agents, risk factors for mastitis occurrence and the control measures suggested by different studies conducted in the selected countries. The literature revealed that India had the highest cattle population. Milking was mainly done by hand in all of the studied countries. Stall feeding was done in Bangladesh and Sri Lanka and limited access to grazing was also reported in some farms in India and Pakistan. There was substantial variation in the prevalence of SCM between studies in all 4 countries, ranging from about 20% to about 80%, but the average prevalence across all studies was high (50%). The most common causal agents for SCM were non-aureus staphylococci (NAS), Staphylococcus (S.) aureus, Streptococcus spp. and Escherichia (E.) coli. The management related risk factors reported for SCM were stall feeding of cows, a higher stock density, cracked floors, open drains, the presence of flies, poor drainage, peri-parturient diseases, infrequent dung removal and earth floors. The control measures suggested in these studies were to improve the hygiene and sanitation of cows, to improve the cleanliness of farms and milker's hands, to apply dry cow therapy, supplementing micronutrients and routine screening for SCM combined with taking intervention measures like isolation of cows or milking infected cows last, and proper treatment. Also, full hand milking, complete milking, machine milking, and providing feed and water immediately after milking have been recommended. Finally, we show that current literature often studies the same set of (non-manageable) risk factors, so more research is needed to obtain a comprehensive picture of the determinants of SCM. Randomized controlled trials are needed to truly quantify the effect of intervention under field conditions. Altogether, our work gives an overview of the udder health situation in South-Asia and provides the basis for the design of UHCP in this region.
Subject(s)
Cattle Diseases , Mastitis, Bovine , Staphylococcal Infections , Animals , Cattle , Dairying , Escherichia coli , Female , Mastitis, Bovine/epidemiology , Mastitis, Bovine/prevention & control , Milk , Prevalence , Risk Factors , Staphylococcal Infections/veterinary , Staphylococcus , Staphylococcus aureusABSTRACT
Most of our understanding of the ecology and evolution of avian influenza A virus (AIV) in wild birds is derived from studies conducted in the northern hemisphere on waterfowl, with a substantial bias towards dabbling ducks. However, relevant environmental conditions and patterns of avian migration and reproduction are substantially different in the southern hemisphere. Through the sequencing and analysis of 333 unique AIV genomes collected from wild birds collected over 15 years we show that Australia is a global sink for AIV diversity and not integrally linked with the Eurasian gene pool. Rather, AIV are infrequently introduced to Australia, followed by decades of isolated circulation and eventual extinction. The number of co-circulating viral lineages varies per subtype. AIV haemagglutinin (HA) subtypes that are rarely identified at duck-centric study sites (H8-12) had more detected introductions and contemporary co-circulating lineages in Australia. Combined with a lack of duck migration beyond the Australian-Papuan region, these findings suggest introductions by long-distance migratory shorebirds. In addition, on the available data we found no evidence of directional or consistent patterns in virus movement across the Australian continent. This feature corresponds to patterns of bird movement, whereby waterfowl have nomadic and erratic rainfall-dependant distributions rather than consistent intra-continental migratory routes. Finally, we detected high levels of virus gene segment reassortment, with a high diversity of AIV genome constellations across years and locations. These data, in addition to those from other studies in Africa and South America, clearly show that patterns of AIV dynamics in the Southern Hemisphere are distinct from those in the temperate north.
Subject(s)
Influenza A virus , Influenza in Birds , Animals , Animals, Wild , Australia/epidemiology , Birds , Ducks , Genetic Variation , Influenza A virus/genetics , Influenza in Birds/epidemiology , PhylogenyABSTRACT
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.
Subject(s)
Influenza A Virus, H9N2 Subtype , Influenza in Birds , Animals , Bangladesh/epidemiology , Chickens , Ducks , Influenza in Birds/epidemiology , Phylogeny , Prevalence , RNA , Risk FactorsABSTRACT
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.
ABSTRACT
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.