African swine fever (ASF) poses a major transboundary threat to swine production in Cambodia and across the Asia-Pacific region, with significant economic and food security implications. A cross-sectional survey was conducted from August to October 2024 to assess the knowledge, attitudes, and practices (KAP) of commercial pig producers in Kampong Speu and Takeo provinces regarding ASF prevention and control. A structured questionnaire was administered to 76 commercial farms housing more than 100 fattening pigs or 50 breeding pigs. Descriptive statistics were used to summarize KAP levels, biosecurity implementation, and challenges, while inferential analyses explored associations among KAP components. Scores were categorized according to Bloom's cut-off criteria as poor (< 60%), moderate (60%-80%), or good (>80%). Respondents generally demonstrated moderate knowledge of ASF characteristics, transmission pathways, and prevention and control measures (73.6%; 95% CI: 64.2-75.5). Nonetheless, notable gaps remained, particularly in recognizing clinical signs and understanding diagnostic procedures ([41.4%; 95% CI: 34.6-49.7). Most producers expressed positive attitudes toward ASF-related biosecurity measures (89.4%; 95% CI: 80.6-94.6) and reported high compliance with hygiene protocols and equipment disinfection (88.3%; 95% CI: 79.0-93.6). No significant associations were found between knowledge and either attitude or practice (p > 0.05), and sociodemographic factors did not significantly influence KAP outcomes (p > 0.05). In conclusion, commercial pig producers demonstrated moderate knowledge and generally positive attitudes toward ASF prevention, with strong implementation of several routine biosecurity and hygiene practices. However, important gaps remained in ASF reporting, visitor-log recording, and emergency preparedness knowledge. To achieve sustainable control, interventions should move beyond information dissemination and promote behavioral change through targeted education, continuous veterinary engagement, and practical biosecurity support. Strengthening these components will be essential for enhancing ASF preparedness and resilience within Cambodia's commercial pig sector, thereby mitigating the risk of disease spread.

Background and Aim: Rabies remains a critical public health threat in Vietnam, particularly in areas where dog-mediated transmission persists. Despite national control strategies, vaccination coverage in dogs remains suboptimal. This study aimed to investigate the perceptions of dog owners toward rabies prevention and control in distinct urban and rural settings of Long An Province, using a Q-sorting methodology to explore sociobehavioral and socioeconomic drivers influencing compliance with vaccination programs. Materials and Methods: A cross-sectional study was conducted among 109 dog owners – 60 from urban Tan An City and 49 from rural Duc Hue District – between March and June 2023. Participants performed Q-sorting with 46 validated statements across four domains: Knowledge, attitudes, practices, and cost perceptions regarding rabies prevention. Principal component analysis was applied separately for each setting to identify latent discourses. Socioeconomic factors were assessed in relation to discourse membership using descriptive and inferential statistics. Results: Two discourses were identified in the urban setting (“Obstructed Adherents” and “Casual Observers”) and three in the rural setting (“Identified Awareness,” “Independent Owners,” and “Close Adherence”). While all participants demonstrated baseline knowledge of rabies severity, barriers such as limited vaccine accessibility and inadequate veterinary support impeded proactive vaccination. Vaccine cost was not perceived as a major deterrent. Educational attainment was significantly associated with proactive health-seeking behavior in the rural setting (p = 0.017). Conclusion: This study elucidates community-specific perceptions that influence rabies prevention behavior. Although awareness of rabies is high, structural limitations – particularly inadequate access to veterinary services – hinder effective control. Tailored community engagement, veterinary outreach, and education campaigns, especially in low-resource settings, are recommended to enhance vaccination uptake and achieve national rabies elimination goals by 2030. Keywords: community perceptions, One Health, Q-sorting, rabies prevention, vaccination barriers, Vietnam.

Campylobacter spp. are major food-borne zoonotic pathogens impacting food safety worldwide. Thailand is one of the countries facing with a significant burden of Campylobacter infections and is recognized as a hotspot of AMR. Our study applied a systematic review and meta-analysis, using a One Health perspective, to investigate the prevalence and AMR of Campylobacter jejuni (C. jejuni) and Campylobacter coli (C. coli) over time in Thailand, from 1985 to 2023. Based on the PRISMA guidelines, a literature search using PubMed, ScienceDirect, and Google Scholar to identify the articles reporting prevalence, sequence types (STs), antimicrobial susceptibility, and resistance genes of Campylobacter spp. in humans, animals, food, and environmental samples was performed. Eighty-one articles were retrieved for systematic review, with 33 reporting Campylobacter spp. prevalence and 20 containing AMR data collected for meta-analysis. The highest prevalence of C. jejuni was found in chickens (43.6 %) and chicken products (31.4 %), followed by ducks (16.7 %), the general human population with diarrhea (15.9 %), children with diarrhea (10.7 %). C. coli was also prevalent in chickens (12.6 %) and chicken products (10.4 %). C. jejuni prevalence decreased by 14.8 % among children with diarrhea (p = 0.006), but increased by 16.7 % in chicken products (p = 0.007). Sixty-two STs were identified, with ST 574, ST 1075, ST 51 being the most prevalent STs recorded. Five STs, including ST 50, ST 51, ST 354, ST 464, and ST 574, were reported in both humans and chickens. The AMR levels were highest against quinolones, ranging 75.4 %–94.8 % in human-related categories and 71.6 %–88.7 % in chicken-related categories. Notably, ciprofloxacin-resistant and nalidixic acid-resistant C. jejuni strains collected from chickens increased by 11.9 % (p = 0.004) and 16.1 % (p = 0.027), respectively. Thirteen resistance genes/mutations were reported, with the phenotypic resistance linked to gyrA mutations and tet(O) genes. The high prevalence and increasing trend of AMR in C. jejuni and C. coli underscore the critical need for One Health surveillance to address the rising AMR challenge posed by these pathogens in Thailand.

Background and Aim: Rabies remains a fatal zoonotic disease of major public health importance in Vietnam, with rising human and animal cases in recent years. Achieving effective control requires high vaccination coverage in dogs and cats, as well as a clear understanding of the behavioral factors influencing vaccination decisions. This cross-sectional analytical study aimed to assess vaccination coverage, examine determinants of proactive vaccination behaviors, and classify pet owners based on their knowledge, attitude, and practice (KAP) regarding rabies prevention in Duc Hue District, Long An Province, during the 2024 mass vaccination campaign. Materials and Methods: The study was conducted across 11 communes between January 10 and April 25, 2024. Data collection included a general household survey and a structured KAP questionnaire. Digital tools such as KoboToolbox, QGIS version 3.36, and RStudio version 4.5.1 were used for data entry, mapping, and statistical analysis. Logistic regression identified demographic and logistical variables associated with proactive vaccination behavior. Principal component analysis (PCA) and cluster analysis (CA) were used to classify pet owners into behavioral groups based on KAP score patterns. Ethical approval was obtained from Nong Lam University and the Long An People's Committee. Results: A total of 6,899 of 8,776 pets were vaccinated, achieving a coverage rate of 78.6%, surpassing the national target of 70% for 2022-2025, although coverage varied widely across communes (60.63%-87.78%). Logistic regression revealed that higher education levels, specific occupations, shorter distance to veterinary services, and smaller total pet populations were significant predictors of proactive vaccination behavior. PCA and CA identified three distinct groups of pet owners. The group with higher education levels and farming occupations demonstrated the strongest KAP profile, while the lowest-performing group was associated with limited education and greater logistical challenges in accessing veterinary services. Conclusion: This study presents the first integrated behavioral-statistical classification of pet owners in southern Vietnam using PCA and clustering, providing a data-driven foundation for more targeted rabies vaccination interventions. Addressing logistical barriers, improving equitable access to veterinary services, and tailoring educational activities toward low-performing groups are essential for sustaining vaccination gains and advancing Vietnam's goal of achieving 80% coverage by 2030.

The zoonosis is a significant health issue for both the medical and veterinary fields. Students in these disciplines play crucial roles in preventing and controlling such diseases. This study aimed to understand the knowledge (K), attitudes (A), and practices (P) regarding the prevention and control of zoonotic diseases among students majoring in animal science and veterinary medicine at the Nong Lam University, Ho Chi Minh City. Two methods used in this cross-sectional study were KAP and Q surveys, conducted on 329 and 46 subjects, respectively. The results indicated that students exhibited good K, A, and P levels at 66%, 48%, and 60%, respectively. The academic year influenced the formation of knowledge and attitudes. Raising two different kinds of animals at home was a factor that influenced the attitudes. The number of information sources affected differences in attitudes and behaviors. Three distinct student clusters were formed based on KAP scores. Cluster 1 had lower scores in all three aspects than the population average, cluster 3 had higher KAP scores than the population average, and cluster 2 had higher KP but lower A than the population average. Two student opinion groups (SOGs) were formed through the Q methodology, where SOG 1 was more concerned about personal health, and SOG 2 was more concerned about animal health. Both groups mentioned interdisciplinary collaboration to address the issue of zoonotic diseases. The proportion of students with good KAP was relatively low, and factors influencing this proportion were identified in the study. Thus, this highlighted the need for additional solutions and enhancements from teachers and researchers with the One Health approach playing a crucial role.

Background and Aim: Rabies is a zoonotic disease that persists endemic in numerous countries worldwide. In Vietnam, the main sources of rabies are dogs and cats, and they caused 76 human deaths annually by 2017-2021. Long An province has recently experienced an increasing burden of rabies, with seven fatal cases reported in the past 5 years. Various rabies control measures have been implemented in this province, including mass vaccination of the animal population, post-vaccination monitoring, diagnostic testing of suspected rabid dogs, dog bite investigation, animal management, pre-exposure treatment, post-exposure treatment (PET), and awareness programs. This study aimed to estimate the cost of rabies control measures for animals and humans in Long An province in 2022. Materials and Methods: An economic model was developed to estimate the costs of rabies control under two scenarios, with and without external financial support from the private sector. Inputs for the model included data from published literature, publicly available reports on rabies, government data, expert opinions, and a pilot study conducted in Vietnam. Results: The total annual costs of rabies control, with or without external support, were estimated to be VND 62.62 and 62.77 billion (equivalent to USD 2.67 and 2.68 million), respectively. The highest proportion of costs was related to PET in humans (84.50% and 84.30%), followed by the cost of mass vaccination paid by animal owners (14.28% and 13.90%). Most of the expenses were paid by the private sector (98.87% and 98.98%) rather than the public sector (1.14% and 1.20%). Conclusion: This study described a transparent and reproducible method for estimating the economic costs of rabies control at the provincial level. The economic model developed showed that control of rabies by mass vaccination is more costeffective than using PET to prevent human death. The model can be applied to future economic analyses of rabies control in other provinces of Vietnam and other rabies-endemic countries.

Antimicrobials are a core aspect of most livestock production systems, especially in low-and middle-income countries. They underpin the efficient use of scarce feed resources and stabilize returns on capital and labor inputs. Antimicrobial use (AMU) contributes to the production of healthy animals, yet AMU in livestock is linked to antimicrobial resistance (AMR) in animals, humans and the environment. The Vietnamese Platform for Antimicrobial Reduction in Chicken Production was implemented during 2016-2019 and was one of Southeast Asia's first interventions focused on AMU reductions in livestock production. The project targeted small-scale commercial poultry farms in the Mekong Delta region of Vietnam using a "randomized before-and-after controlled" study design. It provided farmers with a locally adapted support service (farmer training plan, advisory visits, biosecurity, and antimicrobial replacement products) to help them reduce their reliance on antimicrobials. A partial budget analysis was performed comparing the control group (status-quo) and intervention group (alternative). The median net farm-level benefit of the intervention strategies with the project's support was VND 6.78 million (interquartile range (IR) VND -71.9-89 million) per farm. Without project support the benefit was reduced to VND 5.1 million (IR VND -69.1-87.2 million) to VND 5.3 million (IR -VND 68.9-87.5 million) depending on the antimicrobial alternative product used. At the project level with a focus on AMU and its reduction, subsequently influence on the resistance reduction, our results showed that achieving resistance reduction benefits with the current knowledge and technologies required investment of at least VND 9.1 million (US$ 395.10) per farm during the project's lifetime. The results highlight the positive net profit for the majority of enrolled farms and a reasonable investments from the project. The recommendation focuses on the implementation of policies on financial support, legislation, and information as potential solutions to facilitate the application of intervention strategies to reduce AMU in poultry production.

The usage of antimicrobials in livestock production is a driver for antimicrobial resistance worldwide. Reducing the use of antibiotics in the animal sector is a priority and requires a change in practices. Vietnam has diverse husbandry and antimicrobial use practices. The objective of this study was to determine the socio-economic and technical factors associated with antibiotic usage patterns on chicken farms in the north and south of Vietnam. Semi-structured interviews (n = 34) and on-farm questionnaires (n = 125) were conducted to collect socio-economic, technical, biosecurity, health management, and antibiotic usage data. Using Multivariate Corresponding Analysis, we identified three production systems (A, B, C) and three patterns of antibiotic usage (1, 2, 3). Group A raised indoor exotic chickens in an intensive setting and was associated with group 1, which used antibiotics according to company recommendations for both treatment and prevention. Group C raised free-range chickens for their own consumption and was associated with group 2, which used antibiotics according to drugstore advice for treatment. Finally, group B was a market-oriented, semi-confined system associated with group 3, which practiced experience-based antibiotic use and overuse. Farms in the south of Vietnam were associated with group 3 and those in the north with group 2. The prediction of antibiotic usage patterns based on farming practices could lead to the identification of a group of farms to be targeted in order to foster the more prudent use of antibiotics in Vietnam.

A central aspect of economic evaluations of surveillance components or systems is to estimate the value of the information that is being generated by surveillance. Importantly, the value of information is determined by the user of the information. This value is often realised through decisions on interventions that are implemented to manage disease in populations with the associated reduction of disease costs in human and animal populations including effects on the wider society. The economic efficiency of such processes can be measured within a single sector or across sectors (e.g. animal health surveillance creating benefits streams in human populations) applying standard economic evaluation techniques. Depending on the context, people may have different demands and uses for information expressed in distinct information-seeking behaviour and willingness to pay for information or knowledge. Hence, private and public stakeholders may attribute different values to surveillance depending on their decision needs. Moreover, cultural and socio-economic factors shape not only the value of surveillance, but also people’s decisions around their livelihoods, income generation, prevention, and disease management strategies. Therefore it is important to understand behaviours, processes, motives, and justifications around health management and surveillance. A range of case studies are presented that describe wider benefits of surveillance and illustrate how non-monetary benefits can be assessed using stated preference elicitation methods, such as discrete choice experiment. Moreover, they demonstrate how understanding of local value systems and contexts allows appraising wider surveillance attributes that ultimately affect the performance and economic efficiency of surveillance.

Program of the Second Debrief Meeting on Education and Research FY2021 held at Okayama University with online presentations from abroad on January 25th, 2022

Vietnam is a low- and middle-income country (LMIC), a primary food producer, and an antimicrobial resistance (AMR) hotspot. AMR is recognized as a One Health challenge since it may transfer between humans, animals and the environment. This study aimed to apply systematic review and meta-analysis to investigate the phenotypic profiles and correlations of antimicrobial-resistant Enterobacteriaceae across three compartments: humans, animals and the environment in Vietnam. A total of 89 articles found in PubMed, Science Direct, and Google Scholar databases were retrieved for qualitative synthesis. E. coli and non-typhoidal Salmonella (NTS) were the most common bacterial species in studies of all compartments (60/89 studies). Among antimicrobials classified as critically important, the resistance levels were observed to be highest to quinolones, 3rd generation of cephalosporins, penicillins, and aminoglycosides. Of 89 studies, 55 articles reported the resistance prevalence of E. coli and NTS in healthy humans, animals and the environment against ciprofloxacin, ceftazidime, ampicillin, gentamicin, sulfamethoxazole-trimethoprim, chloramphenicol was used for meta-analysis. The pooled prevalence was found highest in E. coli against ampicillin 84.0% (95% CI 73.0–91.0%) and sulfamethoxazole-trimethoprim 66.0% (95% CI 56.0–75.0%) while in NTS they were 34.0% (95% CI 24.0–46.0%), 33.0% (95% CI 25.0–42.0%), respectively. There were no significant differences in the pooled prevalence of E. coli and NTS to these antimicrobials across healthy humans, animals and the environment, except for ceftazidime-resistant E. coli (χ2 = 8.29, p = 0.02), chloramphenicol-resistant E.coli (χ2 = 9.65, p < 0.01) and chloramphenicol-resistant NTS (χ2 = 7.51, p = 0.02). Findings from the multiple meta-regression models indicated that the AMR levels in E. coli (β = 1.887, p < 0.001) and the North (β = 0.798, p = 0.047) had a higher fraction of AMR than NTS and other regions of Vietnam. The outcomes of this study play an important role as the baseline information for further investigation and follow-up intervention strategies to tackle AMR in Vietnam, and more generally, can be adapted to other LMICs.

Indiscriminate antimicrobial use (AMU) in animal production is a driver of antimicrobial resistance globally. There is a need to define sustainable interventions to reduce AMU in small-scale production systems, which currently represent the most widespread farming systems in South East Asia and many low- and middle-income countries. We conducted a before-and-after intervention study on a random sample of small-scale chicken farms in the Mekong Delta of Vietnam from 2016 to 2019. The study included a baseline followed by an intervention phase where farmers were provided with regular veterinary advice on flock health and husbandry, as well as antimicrobial replacement products. Of 102 recruited farms (raising >100 chickens per flock cycle), thirty-five (34.2%) entered the intervention phase, whilst the rest stopped raising chickens, mainly due to suboptimal flock performance. Through the implementation of our intervention, chicken flocks reduced levels of AMU by 66% [adjusted hazard ratio (HR) = 0.34; p = 0.002) from a baseline of 343.4 Animal Daily Doses per 1,000 chicken-days and decreased weekly mortality by 40% (adjusted HR = 0.60; p = 0.005) from a baseline mortality of 1.60 per 100 birds. Chicken bodyweight increased by 100 g (p = 0.002) in intervention flocks. Our findings demonstrate that the provision of veterinary advice can achieve substantial reductions in AMU in small-scale production systems without compromising flock health and productivity.

Small-scale farming of meat chicken flocks using local native breeds contributes to the economy of many rural livelihoods in Vietnam and many other low- and middle-income countries (LMICs). These systems are also the target of high levels of antimicrobial use (AMU); however, little is known about the profitability and sustainability of such systems. Since small-scale farms are commercial enterprises, this knowledge is essential to develop successful strategies to curb excessive AMU. Using longitudinal data from 203 small-scale (100-2,000 heads) native chicken flocks raised in 102 randomly selected farms in Dong Thap province (Mekong Delta, Vietnam), we investigated the financial and economic parameters of such systems and the main constraints to their sustainability. Feed accounted for the largest financial cost (flock median 49.5 % [Inter-quartile range (IQR) 41.5-61.8 %]) of total costs, followed by day-old-chicks (DOCs) (median 30.3 % [IQR 23.2-38.4 %]), non-antimicrobial health-supporting products (median 7.1 % [IQR 4.7-10.5 %]), vaccines (median 3.1 % [IQR 2.2-4.8 %]), equipment (median 1.9 % [IQR 0.0-4.9 %]) and antimicrobials (median 1.9 % [IQR 0.7-3.6 %]). Excluding labor costs, farmers achieved a positive return on investment (ROI) from 120 (59.1 %) flocks, the remainder generating a loss (median ROI 124 % [IQR 36-206 %]). Higher ROI was associated with higher flock size and low mortality. There was no statistical association between use of medicated feed and flock mortality or chicken bodyweight. The median daily income per person dedicated to raising chickens was 202,100 VND, lower than alternative rural labor activities in the Mekong Delta. In a large proportion of farms (33.4 %), farmers decided to stop raising chickens after completing one cycle. Farmers who dropped off chicken production purchased more expensive feed (in 1000 VND per kg): 11.1 [10.6-11.5] vs. 10.8 [10.4-11.3] for farms that continued production (p = 0.039), and experienced higher chicken mortality (28.5 % [12.0-79.0 %] vs. 16 [7.5-33.0 %]; p = 0.004). The rapid turnover of farmers raising chickens in such systems represents a challenge to the uptake of messages on appropriate AMU and chicken health. To ensure sustainability of small-scale commercial systems, advisory services need to be available to farmers as they initiate new flocks, and support them in the early stages to help overcome their limited experience and skills. This targeted approach would support profitability whilst reducing risk of emergence of AMR and infectious disease from these systems.

Antimicrobials are included in commercial animal feed rations in many low- and middle-income countries (LMICs). We measured antimicrobial use (AMU) in commercial feed products consumed by 338 small-scale chicken flocks in the Mekong Delta of Vietnam, before a gradual nationwide ban on prophylactic use of antimicrobials (including in commercial feeds) to be introduced in the country over the coming five years. We inspected the labels of commercial feeds and calculated amounts of antimicrobial active ingredients (AAIs) given to flocks. We framed these results in the context of overall AMU in chicken production, and highlighted those products that did not comply with Government regulations. Thirty-five of 99 (35.3%) different antimicrobial-containing feed products included at least one AAI. Eight different AAIs (avilamycin, bacitracin, chlortetracycline, colistin, enramycin, flavomycin, oxytetracycline, virginamycin) belonging to five classes were identified. Brooding feeds contained antimicrobials the most (60.0%), followed by grower (40.9%) and finisher feeds (20.0%). Quantitatively, chlortetracycline was consumed most (42.2 mg/kg SEM ±0.34; 50.0% of total use), followed by enramycin (18.4 mg/kg SEM ±0.03, 21.8%), bacitracin (16.4 mg/kg SEM ±0.20, 19.4%) and colistin (6.40 mg/kg SEM ± 4.21;7.6%). Other antimicrobials consumed were virgianamycin, avilamycin, flavomycin and oxytetracycline (each ≤0.50 mg/kg). Antimicrobials in commercial feeds were more commonly given to flocks in the earlier part of the production cycle. A total of 10 (9.3%) products were not compliant with existing Vietnamese regulation (06/2016/TT-BNNPTNT) either because they included a non-authorised AAI (4), had AAIs over the permitted limits (4), or both (2). A number of commercial feed formulations examined included colistin (polymyxin E), a critically important antimicrobial of highest priority for human medicine. These results illustrate the challenges for effective implementation and enforcement of restrictions of antimicrobials in commercial feeds in LMICs. Results from this study should help encourage discussion about policies on medicated feeds in LMICs.

There is a pressing need to establish surveillance systems for antimicrobial use (AMU) intended for animal production particularly in many low- and middle-income countries. This is an extremely challenging task, notably due to the wide range of animal species, production types and antimicrobials available in the market. In Vietnam, farmers commonly buy antimicrobials from veterinary drug shops. Therefore, veterinary drug shops are a potential target for data collection on AMU. We collected antimicrobial sales data at veterinary drug shops and estimated the amount of AMU in different animal species by antimicrobial active ingredient (AAI) class using different measurement metrics. We compiled information on all antimicrobials licensed in Vietnam and used this information to develop a mobile application to capture sales of antimicrobials intended for use in poultry, pig, and ruminant. We provided tablets with this application to 60 veterinary drug shops in two provinces of the country (Bac Giang in the north, Dong Thap in the south; three districts and 30 shops per province) for data collection over 3 weeks. Total sales of antimicrobials were extrapolated to 1 year, and these amounts were related to three different denominator estimates in each province including standing animal body weight, animal biomass, and Population Correction Unit (PCU). A total of 3,960 transactions [2,577 (median 75.5 per shop) in Bac Giang; 1,383 (median 28.5 per shop) in Dong Thap] of 831 different antimicrobial-containing products were recorded in the 3-week period. Sales of 57 AAIs belonging to 17 classes were recorded. In the three Bac Giang districts, we estimated that 242.0 kg of AAI were hypothetically sold over 1 year. Of those, 202.2 kg (83.6%) were intended for poultry, 19.8 kg (8.1%) for pigs, and 20.0 kg (8.3%) for ruminants. In Dong Thap, an estimated 48.4 kg of antimicrobials were sold, including 28.9 kg (59.7%) for poultry, 16.0 kg (33.1%) for pigs, and 3.5 kg (7.2%) for ruminants. After standardized by different animal population denominators, AMU in Bac Giang amounted to 1129.2 mg/kg standing animal body weight, 480.2 mg/kg biomass, and 636.1 mg/kg PCU. In Dong Thap, AMU figures were 1211.0 mg/kg standing animal body weight, 595.8 mg/kg biomass and 818.5 mg/kg PCU. We discuss the observed differences between species, location and metrics, as well as the potential advantages and limitations (including potential sources of bias) of this methodology and its applicability at country level. Retail level data collection can effectively be integrated into AMU surveillance systems that help identify priority AMU management areas (species, regions, and antimicrobial classes), establish national benchmarks and reduction targets.

AbstractBackgroundIn the Mekong Delta region of Vietnam, high quantities of products containing antimicrobial are used as prophylactic and curative treatments in small-scale chicken flocks. A large number of these contain antimicrobial active ingredients (AAIs) considered of ‘critical importance’ for human medicine according to the World Health Organization (WHO). However, little is known about the retail prices of these products and variables associated with the expense on antimicrobials at farm level. Therefore, the aims of the study were: (1) to investigate the retail price of antimicrobials with regards to WHO importance criteria; and (2) to quantify the antimicrobial expense incurred in raising chicken flocks. We investigated 102 randomly-selected small-scale farms raising meat chickens (100–2000 per flock cycle) in two districts in Dong Thap (Mekong Delta) over 203 flock production cycles raised in these farms. Farmers were asked to record the retail prices and amounts of antimicrobial used.ResultsA total of 214 different antimicrobial-containing products were identified. These contained 37 different AAIs belonging to 13 classes. Over half (60.3%) products contained 1 highest priority, critically important AAI, and 38.8% 1 high priority, critically important AAI. The average (farm-adjusted) retail price of a daily dose administered to a 1 kg bird across products was 0.40 cents of 1 US$ (₵) (SE ± 0.05). The most expensive products were those that included at least one high priority, critically important AAI, as well as those purchased in one of the two study districts. Farmers spent on average of ₵3.91 (SE ± 0.01) on antimicrobials per bird over the production cycle. The expense on antimicrobials in weeks with disease and low mortality was greater than on weeks with disease and high mortality, suggesting that antimicrobial use had a beneficial impact on disease outcomes (χ2 = 3.8;p = 0.052). Farmers generally used more expensive antimicrobials on older flocks.Conclusions and recommendationThe retail prices of antimicrobial products used in chicken production in Mekong Delta small-scale chicken farms are very low, and not related to their relevance for human medicine. Farmers, however, demonstrated a degree of sensitivity to prices of antimicrobial products. Therefore, revising pricing policies of antimicrobial products remains a potential option to curb the use of antimicrobials of critical importance in animal production.

Additional file 2. Price estimates of each of antimicrobial-containing products. Price paid by farmers for each purchase of a single antimicrobial-containing product.

Background Antimicrobial growth promoters (AGPs) are included in commercial animal feed rations in many low- and middle-income countries (LMICs). We measured antimicrobial use (AMU) in commercial feed products consumed by 338 small-scale chicken flocks in the Mekong Delta of Vietnam, before a nation-wide ban on AGPs which is to be introduced over the coming three years. We reviewed the labels of commercial feeds and calculated amounts of antimicrobial active ingredients (AAIs) given to flocks. We framed these results in the context of overall AMU in chicken production, and highlighted those products that did not comply with Government regulations. Results Thirty five of 99 different antimicrobial-containing feed products (35.3%) included at least one AAI. Eight different AAIs (avilamycin, bacitracin, chlortetracycline, colistin, enramycin, flavomycin, oxytetracycline, virginamycin) belonging to 5 classes were identified. Brooding feeds contained antimicrobials the most (51.2%), followed by grower (34.6%) and finisher feeds (12.5%). The average amount of AAIs given to flocks per kg of chicken at consumption time was 84.8 (SEM ±9.3mg). Quantitatively, chlortetracycline was consumed most (42.2mg/kg SEM ±0.34; 50.0% of total use), followed by enramycin (18.4mg SEM ±0.03, 21.8%) and bacitracin (16.4mg SEM ±0.20, 19.4%). Antimicrobials in commercial feeds were more commonly given to flocks in the earlier part of the production cycle. A total of 10 (9.3%) products were not compliant with existing Vietnamese regulation (06/2016/TT-BNNPTNT) either because they included a non-authorised AAI (4), had AAIs over the permitted limits (4), or both (2). Conclusions and recommendation Some commercial feed formulations examined included colistin (polymyxin E), a critically important antimicrobial of highest priority for human medicine. A tenth of the formulations examined did not comply with Government regulations. We estimated that consumption of AGPs in feed represented ~10% of total AMU in chicken production. We advocate for restrictions on AMU in chicken production that go beyond phased bans on AGPs. Furthermore, these steps could be bolder and implemented without unnecessary delay. Results from this study should help encourage discussion about policies on AGPs in LMICs.

Abstract Background The Mekong Delta of Vietnam is a hotspot of antimicrobial use (AMU), but there is no information on the quality of the labelling and strength of antimicrobial products used in poultry production. Methods Based on a large random sample of farms, we identified the 20 most used antimicrobial products in the area, and investigated their antimicrobial active ingredient (AAI) content by UPLC‐MS/MS (91 analytical tests). Results Only 17/59 (28.8%) batches contained all AAIs within 10% of the declared strength. Worryingly, 65.0% products provided in their label preparation guidelines for both therapeutic and prophylactic use. Withdrawal times for both meat and eggs were stated in 8/20 (40%) products. Conclusion Results highlight deficiencies in quality and labelling contents that undermine authorities’ efforts to discourage inappropriate use of antimicrobials.

Antimicrobials are used by poultry farmers in Vietnam as a tool to treat and prevent infectious diseases. We aimed to determine the fraction of disease episodes likely to remain untreated due to the administration of antimicrobials on non-susceptible pathogens in chicken flocks in the Mekong Delta of Vietnam. Weekly data on antimicrobial use and clinical signs were collected from 88 randomly chosen chicken flocks over 124 full production cycles (i.e. time between restocking flocks with day-old chicks and sale for slaughter). A naïve Bayes model was trained to infer the probabilities of disease episodes having been caused by each of 24 pathogens, given the observed clinical sign profile, and expert knowledge on their relative incidence. A total of 224 disease episodes were observed, of which 44.8% were attributed to viruses (95% CI 31.1–58.4%), 54.6% (CI 40.4–68.7%) to bacteria, and 0.6% (CI 0–1.7%) to a protozoan (Eimeria spp.). Antimicrobials were more frequently administered on weeks with disease than on weeks without disease (43.3% vs. 17.8%; p < 0.001). A median of 2 [IQR 0–4] antimicrobials were used by episode. The choice of specific antimicrobials was independent on whether the flocks had disease clinical signs or not. Antimicrobials were not used in 30.3% of the episodes. The overall probability that episodes were not effectively treated was 74.2, and 53.7% when discounting cases where the inferred aetiology is viral. Considering only episodes where antimicrobials were given, these probabilities were 57.4 and 23.8% respectively. This study highlights untargeted use of antimicrobials on small-scale Vietnamese chicken farms, as well as the limitations of antimicrobials as effective tools to control infectious diseases.