Trade patterns facilitating highly pathogenic avian influenza virus dissemination in the free-grazing layer duck system in Vietnam

Abstract

SummaryHighly 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. K E Y W O R D Sfree-grazing ducks, highly pathogenic avian influenza, poultry trade, value chain analysis, Vietnam

The impact of surveillance and control on highly pathogenic avian influenza outbreaks in poultry in Dhaka division, Bangladesh

“…In order to reduce such loss they may modify their practices, altering the structure of the trade networks. Reshaping the trade network may in turn modify the disease transmission dynamics and possibly facilitate additional spread [ 36 ].…”

Survivability of highly pathogenic avian influenza virus (H5N1) in naturally preened duck feathers at different temperatures

“…The virus can be transmitted to domestic poultry and mammals including humans (Swayne & Suarez, ). In South East Asia, the key factor in the spread of H5N1 avian influenza virus appears to be the endemic nature of virus in domestic ducks ( A. platyrhynchos var domesticus ), with their rearing in open‐range paddy fields as a possible contributing factor (Meyer et al., ; Sarker, Giasuddin, Chowdhury, & Islam, ). In ducks ( A. platyrhynchos) , respiratory or faeco‐oral route is the two major routes of transmission of the avian influenza virus depending on the virulence (Markwell & Shortridge, ).…”

“…var domesticus), with their rearing in open-range paddy fields as a possible contributing factor (Meyer et al, 2018;Sarker, Giasuddin, Chowdhury, & Islam, 2017). In ducks (A. platyrhynchos), respiratory or faeco-oral route is the two major routes of transmission of the avian influenza virus depending on the virulence (Markwell & Shortridge, 1982).…”

The impact of surveillance and control on highly pathogenic avian inuenza outbreaks in poultry in Dhaka division, Bangladesh

“…An essential part 33 of creating impediments is to establish an environment in which there are relatively few loca- 34 tions that could become easily infected, with vaccination one of the main methods available for 35 achieving such a goal [7]. Vaccination against HPAI aims to prevent clinical disease as well as to 36 reduce levels of virus shed into the environment and stop infection spreading. In parts of Asia, 37 vaccination programs have been implemented and encouraged as part of a control program in 38 poultry.…”

“…In 633 order to reduce such loss they may modify their practices, altering the structure of the trade 634 networks. Reshaping the trade network may in turn modify the disease transmission dynamics 635 and possibly facilitate additional spread [36]. 636 The high density and variety of avian hosts in Bangladeshi LBMs supports the maintenance, am-637 plification and dissemination of avian influenza viruses, whilst providing frequent opportunities 638 for inter-species transmission events [37,38].…”