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Islam A, Hossain ME, Amin E, Islam S, Islam M, Sayeed MA, Hasan MM, Miah M, Hassan MM, Rahman MZ, Shirin T. Epidemiology and phylodynamics of multiple clades of H5N1 circulating in domestic duck farms in different production systems in Bangladesh. Front Public Health 2023; 11:1168613. [PMID: 37483933 PMCID: PMC10358836 DOI: 10.3389/fpubh.2023.1168613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 05/30/2023] [Indexed: 07/25/2023] Open
Abstract
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.
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Affiliation(s)
- Ariful Islam
- EcoHealth Alliance, New York, NY, United States
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Geelong, VIC, Australia
| | - Mohammad Enayet Hossain
- One Health Laboratory, International Centre for Diarrheal Diseases Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Emama Amin
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Shariful Islam
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Monjurul Islam
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Md Abu Sayeed
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Md Mehedi Hasan
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
| | - Mojnu Miah
- One Health Laboratory, International Centre for Diarrheal Diseases Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Mohammad Mahmudul Hassan
- Queensland Alliance for One Health Sciences, School of Veterinary Science, University of Queensland, Brisbane, QLD, Australia
| | - Mohammed Ziaur Rahman
- One Health Laboratory, International Centre for Diarrheal Diseases Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Tahmina Shirin
- Institute of Epidemiology, Disease Control and Research (IEDCR), Dhaka, Bangladesh
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Yoon H, Lee I, Kang H, Kim KS, Lee E. Big data-based risk assessment of poultry farms during the 2020/2021 highly pathogenic avian influenza epidemic in Korea. PLoS One 2022; 17:e0269311. [PMID: 35671297 PMCID: PMC9173618 DOI: 10.1371/journal.pone.0269311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 05/18/2022] [Indexed: 11/19/2022] Open
Abstract
Outbreaks of H5-type highly pathogenic avian influenza (HPAI) in poultry have been reported in various parts of the world. To respond to these continuous threats, numerous surveillance programs have been applied to poultry raising facilities as well as wild birds. In Korea, a surveillance program was developed aimed at providing a preemptive response to possible outbreaks at poultry farms. The purpose of this study is to comprehensively present the risks of HPAI evaluated by this program in relation to actual outbreak farms during the epidemic of 2020/2021. A deep learning-based risk assessment program was trained based on the pattern of livestock vehicles visiting poultry farms and HPAI outbreaks to calculate the risk of HPAI for farms linked by the movement of livestock vehicles (such farms are termed “epidemiologically linked farms”). A total of 7,984 risk assessments were conducted, and the results were categorized into four groups. The proportion of the highest risk level was greater in duck farms (13.6%) than in chicken farms (8.8%). Among the duck farms, the proportion of the highest risk level was much greater in farms where breeder ducks were raised (accounting for 26.4% of the risk) than in farms where ducks were raised to obtain meat (12.8% of the risk). A higher risk level was also found in cases where the species of the outbreak farm and epidemiologically linked farms were the same (proportion of the highest risk level = 13.2%) compared to that when the species between the two farms were different (7.9%). The overall proportion of farms with HPAI outbreaks among epidemiologically linked farms (attack rate, AR) was 1.7% as HPAI was confirmed on 67 of the 3,883 epidemiologically linked farms. The AR was highest for breeder ducks (15.3%) among duck farms and laying hens (4.8%) among chicken farms. The AR of the pairs where livestock vehicles entered the inner farm area was 1.3 times (95% confidence interval: 1.4–2.9) higher than that of all pairs. With the risk information provided, customized preventive measures can be implemented for each epidemiologically linked farm. The use of this risk assessment program would be a good example of information-based surveillance and support decision-making for controlling animal diseases.
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Affiliation(s)
- Hachung Yoon
- Veterinary Epidemiology Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongsangbuk-do, Republic of Korea
- * E-mail:
| | - Ilseob Lee
- Veterinary Epidemiology Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongsangbuk-do, Republic of Korea
| | - Hyeonjeong Kang
- Veterinary Epidemiology Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongsangbuk-do, Republic of Korea
| | - Kyung-Sook Kim
- Veterinary Epidemiology Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongsangbuk-do, Republic of Korea
| | - Eunesub Lee
- Veterinary Epidemiology Division, Animal and Plant Quarantine Agency, Gimcheon, Gyeongsangbuk-do, Republic of Korea
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LE KT, ISODA N, NGUYEN LT, CHU DH, NGUYEN LV, PHAN MQ, NGUYEN DT, NGUYEN TN, TIEN TN, LE TT, HIONO T, MATSUNO K, OKAMATSU M, SAKODA Y. Risk profile of low pathogenicity avian influenza virus infections in farms in southern Vietnam. J Vet Med Sci 2022; 84:860-868. [PMID: 35570003 PMCID: PMC9246698 DOI: 10.1292/jvms.22-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The impact of low pathogenicity avian influenza (LPAI) has been confirmed mainly in
farms. Unlike apparent losses caused by the high pathogenicity avian influenza (HPAI), the
LPAI impact has been hardly evaluated due to underestimating its spread and damage. In
2019, a questionnaire study was conducted in southern Vietnam to identify the specific
risk factors of LPAI virus (LPAIV) circulation and to find associations between husbandry
activities and LPAI prevalence. A multilevel regression analysis indicated that keeping
Muscovy ducks during farming contributed to LPAIV positivity [Odds ratio=208.2 (95%
confidence interval: 13.4–1.1 × 104)]. In cluster analysis, farmers willing to
report avian influenza (AI) events and who agreed with the local AI control policy had a
slightly lower risk for LPAIV infection although there was no significance in the
correlation between farmer characteristics and LPAI occurrence. These findings indicated
that keeping Muscovy ducks without appropriate countermeasures might increase the risk of
LPAIV infection. Furthermore, specific control measures at the local level are effective
for LPAIV circulation, and the improvement of knowledge about biosecurity and attitude
contributes to reducing LPAI damage.
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Affiliation(s)
- Kien Trung LE
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University
| | - Norikazu ISODA
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University
| | - Lam Thanh NGUYEN
- Department of Veterinary Medicine, College of Agriculture, Can Tho University
| | - Duc-Huy CHU
- Department of Animal Health, Ministry of Agriculture and Rural Development
| | - Long Van NGUYEN
- Department of Animal Health, Ministry of Agriculture and Rural Development
| | - Minh Quang PHAN
- Department of Animal Health, Ministry of Agriculture and Rural Development
| | - Diep Thi NGUYEN
- Department of Animal Health, Ministry of Agriculture and Rural Development
| | - Tien Ngoc NGUYEN
- Department of Animal Health, Ministry of Agriculture and Rural Development
| | - Tien Ngoc TIEN
- Regional Animal Health Office VII, Department of Animal Health, Ministry of Agriculture and Rural Development
| | - Tung Thanh LE
- Sub-Departments of Animal Health, Ministry of Agriculture and Rural Development
| | - Takahiro HIONO
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University
| | - Keita MATSUNO
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University
| | - Masatoshi OKAMATSU
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University
| | - Yoshihiro SAKODA
- Laboratory of Microbiology, Department of Disease Control, Faculty of Veterinary Medicine, Hokkaido University
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Khaw SWS, Vu LT, Yulianto D, Meers J, Henning J. Transport of Moving Duck Flocks in Indonesia and Vietnam: Management Practices That Potentially Impact Avian Pathogen Dissemination. Front Vet Sci 2021; 8:673624. [PMID: 34307523 PMCID: PMC8299275 DOI: 10.3389/fvets.2021.673624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/10/2021] [Indexed: 11/13/2022] Open
Abstract
Highly pathogenic avian influenza (HPAI) virus is endemic in Indonesia and Vietnam, where “moving” duck production is commonly practiced. Questionnaire surveys were conducted with transporters of “moving” duck flocks in Indonesia (N = 55) and Vietnam (N = 43). The main purpose of transportation was to transport duck flocks between rice paddies used for scavenging. Trucks were commonly utilized for transport in both countries (Indonesia: 98.2%, 54/55; Vietnam: 37.2%, 16/43), while boats were only used in Vietnam (62.8%, 27/43). Transporters in Vietnam moved larger flocks and traveled over longer distances. Deaths of ducks due to diseases were reported in both countries (Indonesia: 16.4%, 9/55; Vietnam: 4.7%, 2/43; p = 0.11). Throwing away of carcasses was the primary method of disposal of dead birds in Indonesia (60.0%, 33/55), but was not practiced in Vietnam (p < 0.001), while more transporters in Vietnam (34.9%, 15/43) buried carcasses compared to Indonesia (6.8%, 4/55; p = 0.001). Consumption of carcasses (20.9%, 9/43), sale of dead ducks (14.0%, 6/43) and processing of ducks for fish feed (9.3%, 4/43) was conducted in Vietnam, but not in Indonesia. Vehicles were predominantly cleaned in rivers and stored outside in Vietnam, while cleaning and storage was usually conducted in houses/garages in Indonesia. In conclusion, we identified management practices that potentially impact transmission of avian pathogens, such as HPAI virus. In Indonesia, unsafe management practices were related to multipurpose usage of transport vehicles and disposal of birds in the environment, while in Vietnam, they were related to the mixing of birds during transport, the processing of dead carcasses and the storage and cleaning of transport vehicles.
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Affiliation(s)
- Shan Wen Stacy Khaw
- School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
| | - Le Tri Vu
- Regional Animal Health Centre VI, Ho Chi Minh City, Vietnam
| | | | - Joanne Meers
- School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
| | - Joerg Henning
- School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
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Pham LD, Do DN, Nam LQ, Van Ba N, Ninh PH, Thuy DP, Son PV, Thieu PC. Evaluation of genetic diversity and population structure in four indigenous duck breeds in Vietnam. Anim Biotechnol 2021; 33:1065-1072. [PMID: 33451256 DOI: 10.1080/10495398.2020.1868485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
This study characterized genetic diversity and population structure of four indigenous Vietnamese duck breeds and an exotic breed for setting the conservation priority. A total of 200 samples from four duck breeds (Sincheng, Minhhuong, Muongchieng and Bauben) and an exotic breed (Supermeat) were genotyped for fifteen microsatellite markers. The average number of alleles per locus was 14.07. A moderate genetic diversity was observed for indigenous breeds as mean of observed and expected heterozygosity as Ho = 0.50 and He = 0.57, respectively. The Bauben had the lowest values of Ho (0.41) and He (0.48) while Sincheng had the highest values of Ho (0.6) and He (0.69), respectively. The inbreeding coefficients (FIS) ranged from 0.12 to 0.16, and all breeds were significantly under heterozygote deficit. Nei's genetic distance was the shortest between Minhhuong and Muongkhieng. The discriminant analysis of principal components of studied breeds resulted in four genetic clusters. The Minhhuong and Muongkhieng breeds joined the same genetic cluster while other breeds had their own clusters. These results indicated that the possibility to combine Minhhuong and Muongkhieng for reducing the cost of conservation and suggested that conservation of the Bauben should be prioritized to avoid inbreeding depression and genetic drift.
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Affiliation(s)
- Lan Doan Pham
- Key Laboratory of Animal Cell Technology, National Institute of Animal Sciences, Hanoi, Vietnam
| | - Duy Ngoc Do
- Institute of Research and Development, Duy Tan University, Danang, Vietnam.,Faculty of Environmental and Chemical Engineering, Duy Tan University, Danang, Vietnam
| | - Le Quang Nam
- Key Laboratory of Animal Cell Technology, National Institute of Animal Sciences, Hanoi, Vietnam
| | - Nguyen Van Ba
- Key Laboratory of Animal Cell Technology, National Institute of Animal Sciences, Hanoi, Vietnam
| | - Pham Hai Ninh
- Key Laboratory of Animal Cell Technology, National Institute of Animal Sciences, Hanoi, Vietnam
| | - Doan Phuong Thuy
- Faculty of Veterinary and Animal Husbandry, BacGiang Agriculture & Forestry University, Bacgiang, Vietnam
| | - Pham Van Son
- Key Laboratory of Animal Cell Technology, National Institute of Animal Sciences, Hanoi, Vietnam
| | - Pham Cong Thieu
- Key Laboratory of Animal Cell Technology, National Institute of Animal Sciences, Hanoi, Vietnam
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Transmission of highly pathogenic avian influenza in the nomadic free-grazing duck production system in Viet Nam. Sci Rep 2020; 10:8432. [PMID: 32439997 PMCID: PMC7242457 DOI: 10.1038/s41598-020-65413-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 04/28/2020] [Indexed: 12/02/2022] Open
Abstract
The presence of free-grazing ducks (FGD) has consistently been shown to be associated with highly pathogenic avian influenza virus (HPAIV) H5N1 outbreaks in South-East Asia. However, the lack of knowledge about the transmission pathways limits the effectiveness of control efforts. To address this gap, we developed a probabilistic transmission model of HPAIV H5N1 in the nomadic FGD production system in Viet Nam, assuming different scenarios to address parameter uncertainty. Results suggested that HPAIV H5N1 could spread within the nomadic FGD production system, with an estimated flock-level effective reproduction number (re) ranging from 2.16 (95% confidence interval (CI): 1.39-3.49) to 6.10 (95%CI: 3.93-9.85) depending on the scenario. Indirect transmission via boats and trucks was shown to be the main transmission route in all scenarios. Results suggest that re could be reduced below one with 95% confidence if 86% of FGD flocks were vaccinated in the best-case scenario or 95% in the worst-case scenario. If vaccination was combined with cleaning and disinfection of transport vehicles twice a week, vaccination coverage could be lowered to 60% in the best-case scenario. These findings are of particular relevance for prioritising interventions for effective control of HPAIV in nomadic free-grazing duck production systems.
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Delabouglise A, Nguyen-Van-Yen B, Thanh NTL, Xuyen HTA, Tuyet PN, Lam HM, Boni MF. Poultry population dynamics and mortality risks in smallholder farms of the Mekong river delta region. BMC Vet Res 2019; 15:205. [PMID: 31208467 PMCID: PMC6580564 DOI: 10.1186/s12917-019-1949-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 06/04/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Poultry farming is widely practiced by rural households in Vietnam and the vast majority of domestic birds are kept on small household farms. However, smallholder poultry production is constrained by several issues such as infectious diseases, including avian influenza viruses whose circulation remains a threat to public health. This observational study describes the demographic structure and dynamics of small-scale poultry farms of the Mekong river delta region. METHOD Fifty three farms were monitored over a 20-month period, with farm sizes, species, age, arrival/departure of poultry, and farm management practices recorded monthly. RESULTS Median flock population sizes were 16 for chickens (IQR: 10-40), 32 for ducks (IQR: 18-101) and 11 for Muscovy ducks (IQR: 7-18); farm size distributions for the three species were heavily right-skewed. Muscovy ducks were kept for long periods and outdoors, while chickens and ducks were farmed indoors or in pens. Ducks had a markedly higher removal rate (broilers: 0.14/week; layer/breeders: 0.05/week) than chickens and Muscovy ducks (broilers: 0.07/week; layer/breeders: 0.01-0.02/week) and a higher degree of specialization resulting in a substantially shorter life span. The rate of mortality due to disease did not differ much among species, with birds being less likely to die from disease at older ages, but frequency of disease symptoms differed by species. Time series of disease-associated mortality were correlated with population size for Muscovy ducks (Kendall's coefficient τ = 0.49, p-value < 0.01) and with frequency of outdoor grazing for ducks (τ = 0.33, p-value = 0.05). CONCLUSION The study highlights some challenges to disease control in small-scale multispecies poultry farms. The rate of interspecific contact and overlap between flocks of different ages is high, making small-scale farms a suitable environment for pathogens circulation. Muscovy ducks are farmed outdoors with little investment in biosecurity and few inter-farm movements. Ducks and chickens are more at-risk of introduction of pathogens through movements of birds from one farm to another. Ducks are farmed in large flocks with high turnover and, as a result, are more vulnerable to disease spread and require a higher vaccination coverage to maintain herd immunity.
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Affiliation(s)
- Alexis Delabouglise
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, Millenium Sciences Complex, Pollock road, University Park, PA, 16802, USA.
| | - Benjamin Nguyen-Van-Yen
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,École Normale Supérieure, CNRS UMR 8197, 46 rue d'Ulm, Paris, France
| | - Nguyen Thi Le Thanh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Huynh Thi Ai Xuyen
- Ca Mau sub-Department of Livestock Production and Animal Health, Ca Mau, Vietnam
| | - Phung Ngoc Tuyet
- Ca Mau sub-Department of Livestock Production and Animal Health, Ca Mau, Vietnam
| | - Ha Minh Lam
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Maciej F Boni
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, Millenium Sciences Complex, Pollock road, University Park, PA, 16802, USA.,Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam.,Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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8
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Nguyen LT, Stevenson MA, Firestone SM, Sims LD, Chu DH, Nguyen LV, Nguyen TN, Le KT, Isoda N, Matsuno K, Okamatsu M, Kida H, Sakoda Y. Spatiotemporal and risk analysis of H5 highly pathogenic avian influenza in Vietnam, 2014-2017. Prev Vet Med 2019; 178:104678. [PMID: 31113666 DOI: 10.1016/j.prevetmed.2019.04.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 03/10/2019] [Accepted: 04/13/2019] [Indexed: 10/27/2022]
Abstract
The aim of this study was to describe the spatiotemporal distribution of H5 HPAI outbreak reports for the period 2014-2017 and to identify factors associated with H5 HPAI outbreak reports. Throughout the study period, a total of 139 outbreaks of H5 HPAI in poultry were reported, due to either H5N1 (96 outbreaks) or H5N6 (43 outbreaks) subtype viruses. H5N1 HPAI outbreaks occurred in all areas of Vietnam while H5N6 HPAI outbreaks were only reported in the northern and central provinces. We counted the number of H5N1 and H5N6 outbreak report-positive districts per province over the four-year study period and calculated the provincial-level standardized morbidity ratio for H5N1 and H5N6 outbreak reports as the observed number of positive districts divided by the expected number. A mixed-effects, zero-inflated Poisson regression model was developed to identify risk factors for outbreak reports of each H5N1 and H5N6 subtype virus. Spatially correlated and uncorrelated random effects terms were included in this model to identify areas of the country where outbreak reports occurred after known risk factors had been accounted-for. The presence of an outbreak report in a province in the previous 6-12 months increased the provincial level H5N1 outbreak report risk by a factor of 2.42 (95% Bayesian credible interval [CrI] 1.27-4.60) while 1000 bird increases in the density of chickens decreased provincial level H5N6 outbreak report risk by a factor of 0.65 (95% CrI 0.38 to 0.97). We document distinctly different patterns in the spatial and temporal distribution of H5N1 and H5N6 outbreak reports. Most of the variation in H5N1 report risk was accounted-for by the fixed effects included in the zero-inflated Poisson model. In contrast, the amount of unaccounted-for risk in the H5N6 model was substantially greater than the H5N1 model. For H5N6 we recommend that targeted investigations should be carried out in provinces with relatively large spatially correlated random effect terms to identify likely determinants of disease. Similarly, investigations should be carried out in provinces with relatively low spatially correlated random effect terms to identify protective factors for disease and/or reasons for failure to report.
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Affiliation(s)
- Lam Thanh Nguyen
- Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan; Department of Veterinary Medicine, College of Agriculture, Can Tho University, Campus II, 3/2 Street, Ninh Kieu, Can Tho, Viet Nam
| | - Mark A Stevenson
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia.
| | - Simon M Firestone
- Asia-Pacific Centre for Animal Health, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Leslie D Sims
- Asia Pacific Veterinary Information Services, Montmorency, Victoria, 3094, Australia
| | - Duc Huy Chu
- Department of Animal Health, Ministry of Agriculture and Rural Development, Ha Noi, Viet Nam
| | - Long Van Nguyen
- Department of Animal Health, Ministry of Agriculture and Rural Development, Ha Noi, Viet Nam
| | - Tien Ngoc Nguyen
- Department of Animal Health, Ministry of Agriculture and Rural Development, Ha Noi, Viet Nam
| | - Kien Trung Le
- Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan
| | - Norikazu Isoda
- Research Center for Zoonosis Control, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido, 001-0020, Japan; Global Institution for Collaborative Research and Education, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Keita Matsuno
- Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan; Global Institution for Collaborative Research and Education, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Masatoshi Okamatsu
- Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan
| | - Hiroshi Kida
- Research Center for Zoonosis Control, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido, 001-0020, Japan; Global Institution for Collaborative Research and Education, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan
| | - Yoshihiro Sakoda
- Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, North 18, West 9, Kita-ku, Sapporo, Hokkaido, 060-0818, Japan; Global Institution for Collaborative Research and Education, Hokkaido University, North 20, West 10, Kita-ku, Sapporo, Hokkaido 001-0020, Japan.
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9
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Gilbert M, Prosser DJ, Zhang G, Artois J, Dhingra MS, Tildesley M, Newman SH, Guo F, Black P, Claes F, Kalpradvidh W, Shin Y, Jeong W, Takekawa JY, Lee H, Xiao X. Could Changes in the Agricultural Landscape of Northeastern China Have Influenced the Long-Distance Transmission of Highly Pathogenic Avian Influenza H5Nx Viruses? Front Vet Sci 2017; 4:225. [PMID: 29312966 PMCID: PMC5742135 DOI: 10.3389/fvets.2017.00225] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 12/06/2017] [Indexed: 11/29/2022] Open
Abstract
In the last few years, several reassortant subtypes of highly pathogenic avian influenza viruses (HPAI H5Nx) have emerged in East Asia. These new viruses, mostly of subtype H5N1, H5N2, H5N6, and H5N8 belonging to clade 2.3.4.4, have been found in several Asian countries and have caused outbreaks in poultry in China, South Korea, and Vietnam. HPAI H5Nx also have spread over considerable distances with the introduction of viruses belonging to the same 2.3.4.4 clade in the U.S. (2014–2015) and in Europe (2014–2015 and 2016–2017). In this paper, we examine the emergence and spread of these new viruses in Asia in relation to published datasets on HPAI H5Nx distribution, movement of migratory waterfowl, avian influenza risk models, and land-use change analyses. More specifically, we show that between 2000 and 2015, vast areas of northeast China have been newly planted with rice paddy fields (3.21 million ha in Heilongjiang, Jilin, and Liaoning) in areas connected to other parts of Asia through migratory pathways of wild waterfowl. We hypothesize that recent land use changes in northeast China have affected the spatial distribution of wild waterfowl, their stopover areas, and the wild-domestic interface, thereby altering transmission dynamics of avian influenza viruses across flyways. Detailed studies of the habitat use by wild migratory birds, of the extent of the wild–domestic interface, and of the circulation of avian influenza viruses in those new planted areas may help to shed more light on this hypothesis, and on the possible impact of those changes on the long-distance patterns of avian influenza transmission.
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Affiliation(s)
- Marius Gilbert
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, Brussels, Belgium.,Fonds National de la Recherche Scientifique (FNRS), Brussels, Belgium
| | - Diann J Prosser
- Patuxent Wildlife Research Center, United States Geological Survey, Beltsville, MD, United States
| | - Geli Zhang
- Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK, United States
| | - Jean Artois
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, Brussels, Belgium
| | - Madhur S Dhingra
- Spatial Epidemiology Lab (SpELL), Université Libre de Bruxelles, Brussels, Belgium
| | - Michael Tildesley
- School of Life Sciences, University of Warwick, Warwick, United Kingdom
| | - Scott H Newman
- Food and Agriculture Organization of the United Nations, Addis Ababa, Ethiopia
| | - Fusheng Guo
- Regional Office for Asia and the Pacific, Food and Agriculture Organization of the United Nations, Bangkok, Thailand
| | - Peter Black
- Regional Office for Asia and the Pacific, Food and Agriculture Organization of the United Nations, Bangkok, Thailand
| | - Filip Claes
- Regional Office for Asia and the Pacific, Food and Agriculture Organization of the United Nations, Bangkok, Thailand
| | - Wantanee Kalpradvidh
- Regional Office for Asia and the Pacific, Food and Agriculture Organization of the United Nations, Bangkok, Thailand
| | - YeunKyung Shin
- Regional Office for Asia and the Pacific, Food and Agriculture Organization of the United Nations, Bangkok, Thailand
| | - Wooseog Jeong
- Animal and Plant Quarantine Agency, Ministry of Agriculture, Food and Rural Affairs, Gimcheon, South Korea
| | - John Y Takekawa
- San Francisco Bay Estuary Field Station, Western Ecological Research Center, United States Geological Survey, Vallejo, CA, United States.,Richardson Bay Audubon Center & Sanctuary, Tiburon, CA, United States
| | - Hansoo Lee
- Korea Institute of Environmental Ecology, Daejeon, South Korea
| | - Xiangming Xiao
- Department of Microbiology and Plant Biology, Center for Spatial Analysis, University of Oklahoma, Norman, OK, United States.,Institute of Biodiversity Science, Fudan University, Shanghai, China
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10
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Meyer A, Dinh TX, Han TA, Do DV, Nhu TV, Pham LT, Nguyen TTT, Newman S, Häsler B, Pfeiffer DU, Vergne T. Trade patterns facilitating highly pathogenic avian influenza virus dissemination in the free-grazing layer duck system in Vietnam. Transbound Emerg Dis 2017; 65:408-419. [PMID: 28815990 DOI: 10.1111/tbed.12697] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Indexed: 11/29/2022]
Abstract
Highly pathogenic avian influenza (HPAI) viruses continue to threaten smallholder poultry producers in several South-east Asian countries, including Vietnam. In particular, the free-grazing duck system has been repeatedly highlighted as a major risk factor for HPAI outbreaks. Free-grazing ducks, which scavenge on rice paddies after the harvest, account for a large proportion of the duck population in Vietnam and the wider South-east Asian region. However, the structure and dynamics of the free-grazing duck production from farm to consumption has not been described for Vietnam. In this study, we used a value chain approach to provide a complete picture of the actors involved in the production and marketing of free-grazing duck eggs and spent layer ducks, as well as to investigate the governance structure of this food system. Group interviews and key informant interviews were conducted in two provinces located in the Mekong River Delta (MRD) and the Red River Delta (RRD). The results presented here highlight similarities and differences in farming and trade practices between the two provinces. The trade of spent layer ducks involved large volumes of live ducks being sent to China and Cambodia for consumption, generating a substantial risk of transboundary spread of pathogens, including HPAI viruses. We describe the major role of "duck yards", which act as hubs in the northbound trade of spent layer ducks. These yards should be considered as essential links in the value chain of spent layer ducks when considering HPAI surveillance and control. The veterinary authorities are only marginally involved in the value chain activities, and their influence could be strengthened by increasing surveillance activities for instance in duck yards. Last, we discuss the dynamics of the duck value chain and further implications for future HPAI management policies.
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Affiliation(s)
- A Meyer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, UK
| | - T X Dinh
- National Institute for Animal Sciences, Hanoi, Vietnam
| | - T A Han
- National Institute for Animal Sciences, Hanoi, Vietnam
| | - D V Do
- National Institute for Animal Sciences, Hanoi, Vietnam
| | - T V Nhu
- National Institute for Animal Sciences, Hanoi, Vietnam
| | - L T Pham
- Department of Animal Health, Ministry of Agriculture and Rural Development, Hanoi, Vietnam
| | - T T T Nguyen
- Emergency Centre for Transboundary Animal Diseases, Food and Agriculture Organization of the United Nations, Hanoi, Vietnam
| | - S Newman
- Emergency Centre for Transboundary Animal Diseases, Food and Agriculture Organization of the United Nations, Hanoi, Vietnam
| | - B Häsler
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, UK
| | - D U Pfeiffer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, UK.,School of Veterinary Medicine, City University of Hong Kong, Hong Kong SAR, China
| | - T Vergne
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, UK.,MIVEGEC Group (UMR CNRS/IRD/UM2), Montpellier, France
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11
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Meyer A, Dinh TX, Nhu TV, Pham LT, Newman S, Nguyen TTT, Pfeiffer DU, Vergne T. Movement and contact patterns of long-distance free-grazing ducks and avian influenza persistence in Vietnam. PLoS One 2017. [PMID: 28632789 PMCID: PMC5478089 DOI: 10.1371/journal.pone.0178241] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Presence of ducks, and in particular of free-grazing ducks, has consistently been shown to be one of the most important risk factors for highly pathogenic avian influenza outbreaks which has compromised poultry production in South-East Asia since the early 2000s and continues to threaten public health, farmers’ livelihood and food security. Although free-grazing duck production has been practised for decades in South-East Asia, there are few published studies describing this production system, which is suspected to play an important role in the maintenance of avian influenza viruses. This study aimed at describing quantitatively the long-distance free-grazing duck production system in South Vietnam, characterising the movement and contact patterns of the duck flocks, and identifying potential associations between farming practices, movement and contact patterns and the circulation of avian influenza viruses. We conducted interviews among stakeholders involved in the free-grazing duck production system (duck farmers, transporters and rice paddy owners) in combination with a virological cross-sectional survey in South Vietnam. Results show that both direct and indirect contacts between free-grazing duck flocks were frequent and diverse. The flocks were transported extensively across district and province boundaries, mainly by boat but also by truck or on foot. A third of the investigated flocks had a positive influenza A virology test, indicating current circulation of avian influenza viruses, but none were positive for H5 subtypes. The age and size of the flock as well as its location at the time of sampling were associated with the risk of influenza A circulation in the flocks. These findings should be considered when developing risk assessment models of influenza virus spread aimed at informing the development of improved biosecurity practices leading to enhanced animal health, sustainable animal production and reliable income for farmers.
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Affiliation(s)
- Anne Meyer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, United-Kingdom
- * E-mail:
| | | | - Thu Van Nhu
- National Institute for Animal Sciences, Hanoi, Vietnam
| | - Long Thanh Pham
- Department of Animal Health, Ministry of Agriculture and Rural Development, Hanoi, Vietnam
| | - Scott Newman
- Emergency Centre for Transboundary Animal Diseases, Food and Agriculture Organization of the United Nations, Hanoi, Vietnam
| | - Thuy Thi Thanh Nguyen
- Emergency Centre for Transboundary Animal Diseases, Food and Agriculture Organization of the United Nations, Hanoi, Vietnam
| | - Dirk Udo Pfeiffer
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, United-Kingdom
- School of Veterinary Medicine, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Timothée Vergne
- Veterinary Epidemiology, Economics and Public Health Group, Royal Veterinary College, London, United-Kingdom
- MIVEGEC (Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle) Group, Institut de Recherche pour le Développement (IRD-224, CNRS-5290, Université de Montpellier 2), Montpellier, France
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12
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Sarkar S, Khan SU, Mikolon A, Rahman MZ, Abedin J, Zeidner N, Sturm‐Ramirez K, Luby SP. An epidemiological study of avian influenza A (H5) virus in nomadic ducks and their raising practices in northeastern Bangladesh, 2011-2012. Influenza Other Respir Viruses 2017; 11:275-282. [PMID: 27966289 PMCID: PMC5410719 DOI: 10.1111/irv.12438] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2016] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND In Bangladesh, nomadic duck flocks are groups of domestic ducks reared for egg production that are moved to access feeding sites beyond their owners' village boundaries and are housed overnight in portable enclosures in scavenging areas. The objectives of this study were to measure the prevalence of influenza A virus RNA and H5-specific antibodies in nomadic ducks and to characterize nomadic duck raising practices in northeastern Bangladesh. METHODS We tested duck egg yolk specimens by competitive ELISA to detect antibodies against avian influenza A (H5) and environmental fecal samples by real-time reverse-transcription polymerase chain reaction (rRT-PCR) to detect influenza A virus RNA and H5 subtype. RESULTS The median age of the ducks was 24 months (range: 8-36 months) and the median flock size was 300 ducks (range: 105-1100). Of 1860 egg yolk samples, 556 (30%, 95% confidence interval (CI): 28-32) were positive for antibodies against H5 and 58 flocks (94%) had at least one egg with H5-specific antibodies. Of 496 fecal samples, 121 (24%, 95% CI: 22-29) had detectable influenza A RNA. Thirty-three flocks (53%) had at least one fecal sample positive for influenza A RNA. CONCLUSIONS Nomadic ducks in Bangladesh are commonly infected with avian influenza A (H5) virus and may serve as a bridging host for transmission of avian influenza A (H5) virus or other avian influenza A viruses subtypes between wild waterfowl, backyard poultry, and humans in Bangladesh.
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Affiliation(s)
- Shamim Sarkar
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
| | - Salah Uddin Khan
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
- College of Public Health and Health Professionals and Emerging Pathogen InstituteUniversity of FloridaGainesvilleFLUSA
| | - Andrea Mikolon
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
- California Department of Food &AgricultureOntarioCAUSA
| | - Mohammad Ziaur Rahman
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
| | - Jaynal Abedin
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
| | - Nord Zeidner
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
- Centers for Disease Control and Prevention (CDC)AtlantaGAUSA
| | - Katherine Sturm‐Ramirez
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
- Centers for Disease Control and Prevention (CDC)AtlantaGAUSA
| | - Stephen P. Luby
- Programme on Emerging Infections (PEI)Infectious Diseases Division (IDD)icddr,b, DhakaBangladesh
- Centers for Disease Control and Prevention (CDC)AtlantaGAUSA
- Center for Innovation in Global HealthStanford UniversityStanfordCAUSA
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13
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Cuong NV, Truc VNT, Nhung NT, Thanh TT, Chieu TTB, Hieu TQ, Men NT, Mai HH, Chi HT, Boni MF, van Doorn HR, Thwaites GE, Carrique-Mas JJ, Hoa NT. Highly Pathogenic Avian Influenza Virus A/H5N1 Infection in Vaccinated Meat Duck Flocks in the Mekong Delta of Vietnam. Transbound Emerg Dis 2016; 63:127-35. [PMID: 26748550 PMCID: PMC4819680 DOI: 10.1111/tbed.12470] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 11/26/2022]
Abstract
We investigated episodes of suspected highly pathogenic avian influenza (HPAI)-like illness among 12 meat duck flocks in two districts in Tien Giang province (Mekong Delta, Vietnam) in November 2013. In total, duck samples from 8 of 12 farms tested positive for HPAI virus subtype A/haemagglutinin 5 and neuraminidase 1 (H5N1) by real-time RT-PCR. Sequencing results confirmed clade of 2.3.2.1.c as the cause of the outbreaks. Most (7/8) laboratory-confirmed positive flocks had been vaccinated with inactivated HPAI H5N1 clade 2.3.4 vaccines <6 days prior to onset of clinical signs. A review of vaccination data in relation to estimated production in the area suggested that vaccination efforts were biased towards larger flocks and that vaccination coverage was low [21.2% ducks vaccinated with two shots (range by district 7.4-34.9%)]. The low-coverage data, the experimental evidence of lack of cross-protection conferred by the currently used vaccines based on clade 2.3.4 together with the short lifespan of meat duck flocks (60-70 days), suggest that vaccination is not likely to be effective as a tool for control of H5N1 infection in meat duck flocks in the area.
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Affiliation(s)
- N V Cuong
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
| | - V N T Truc
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
- University of Science, Ho Chi Minh City, Vietnam
| | - N T Nhung
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
| | - T T Thanh
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
| | - T T B Chieu
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
| | - T Q Hieu
- Sub-Department of Animal Health, Tien Giang Province, Vietnam
| | - N T Men
- Sub-Department of Animal Health, Tien Giang Province, Vietnam
| | - H H Mai
- Sub-Department of Animal Health, Tien Giang Province, Vietnam
| | - H T Chi
- Sub-Department of Animal Health, Tien Giang Province, Vietnam
| | - M F Boni
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, UK
| | - H R van Doorn
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, UK
| | - G E Thwaites
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, UK
| | - J J Carrique-Mas
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, UK
| | - N T Hoa
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Hospital for Tropical Disease, Ho Chi Minh City, Vietnam
- Centre for Tropical Medicine, Nuffield Department of Medicine, University of Oxford, UK
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14
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Pantin-Jackwood MJ, Suarez DL. Vaccination of domestic ducks against H5N1 HPAI: A review. Virus Res 2013; 178:21-34. [DOI: 10.1016/j.virusres.2013.07.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Revised: 05/21/2013] [Accepted: 07/18/2013] [Indexed: 01/08/2023]
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15
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Boni MF, Galvani AP, Wickelgren AL, Malani A. Economic epidemiology of avian influenza on smallholder poultry farms. Theor Popul Biol 2013; 90:135-44. [PMID: 24161559 PMCID: PMC3851691 DOI: 10.1016/j.tpb.2013.10.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 08/03/2013] [Accepted: 10/08/2013] [Indexed: 11/01/2022]
Abstract
Highly pathogenic avian influenza (HPAI) is often controlled through culling of poultry. Compensating farmers for culled chickens or ducks facilitates effective culling and control of HPAI. However, ensuing price shifts can create incentives that alter the disease dynamics of HPAI. Farmers control certain aspects of the dynamics by setting a farm size, implementing infection control measures, and determining the age at which poultry are sent to market. Their decisions can be influenced by the market price of poultry which can, in turn, be set by policy makers during an HPAI outbreak. Here, we integrate these economic considerations into an epidemiological model in which epidemiological parameters are determined by an outside agent (the farmer) to maximize profit from poultry sales. Our model exhibits a diversity of behaviors which are sensitive to (i) the ability to identify infected poultry, (ii) the average price of infected poultry, (iii) the basic reproductive number of avian influenza, (iv) the effect of culling on the market price of poultry, (v) the effect of market price on farm size, and (vi) the effect of poultry density on disease transmission. We find that under certain market and epidemiological conditions, culling can increase farm size and the total number of HPAI infections. Our model helps to inform the optimization of public health outcomes that best weigh the balance between public health risk and beneficial economic outcomes for farmers.
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Affiliation(s)
- Maciej F Boni
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Viet Nam; Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
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16
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A one health perspective on HPAI H5N1 in the Greater Mekong sub-region. Comp Immunol Microbiol Infect Dis 2012; 36:309-19. [PMID: 23260375 DOI: 10.1016/j.cimid.2012.11.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Revised: 11/18/2012] [Accepted: 11/24/2012] [Indexed: 11/23/2022]
Abstract
Highly pathogenic avian influenza H5N1 has been a global concern for almost 10 years since its epidemic emergence in South-east Asia in 2003/2004. Despite large investment of resources into the region, the infection has not been eradicated and continues to result in outbreaks in poultry and a small number of human fatalities. This review synthesizes the knowledge base generated by a vast number of research activities conducted in the region and beyond, and adopts an interdisciplinary perspective consistent with the one health paradigm towards analysing the problem and formulating possible policy solutions. A key outcome of the work has been the need to integrate socio-economic and anthropological dimensions with any disease control and prevention activities traditionally informed by primarily epidemiological, virological and pathological attributes of the infection in poultry and wild waterbirds. Recommendations at a broad conceptual level are presented that acknowledge the diversity in the region with respect to livestock production, as well as the changing nature of the risk landscape as a consequence of the rapid economic development which some of the countries in the Greater Mekong sub-region are currently undergoing, as well as their strong trade links with China as the major economic power in East Asia.
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