Dynamics of inter-farm transmission of highly pathogenic avian influenza H5N6 integrating vehicle movements and phylogenetic information

Abstract

Highly pathogenic avian influenza (HPAI) in poultry holdings commonly spreads through animal trade, and poultry production and health-associated vehicle (PPHaV) movement. To effectively control the spread of disease, it is essential that the contact structure via those movements among farms is thoroughly explored. However, few attempts have been made to scrutinize PPHaV movement compared to poultry trade. Therefore, our study aimed to elucidate the role of PPHaV movement on HPAI transmission. We performed network analysis using PPHaV movement data based on a global positioning system, with phylogenetic information of the isolates during the 2016–2017 HPAI H5N6 epidemic in the Republic of Korea. Moreover, the contribution of PPHaV movement to the spread of HPAI was estimated by Bayesian modeling. The network analysis revealed that there was the relationship between phylogenetic clusters and the contact network via PPHaV movement. Furthermore, the similarity of farm poultry species and the shared integrators between inter-linked infected premises (IPs) were associated with ties within the same phylogenetic clusters. Additionally, PPHaV movement among phylogenetically clustered IPs was estimated to contribute to approximately 30% of HPAI H5N6 infections in IPs on average. This study provides insight into how HPAI spread via PPHaV movement and scientific basis for control strategies.

Spatial epidemiology of highly pathogenic avian influenza subtype H5N6 in Gyeonggi Province, South Korea, 2016–2017

“…This is consistent with previous studies from around the world (Gilbert & Pfeiffer, 2012) and South Korea (An et al., 2021) indicating that high poultry density is a proxy of contact opportunities between farms including vehicle movements or networks between farmers and the increased poultry‐related activities, which can explain the increased likelihood of HPAI H5N6 infections in the study area (Bonney et al., 2018; Liang et al., 2020; Walsh et al., 2020). Given the findings of a previous study in South Korea (Yoo et al., 2021), which estimated that vehicle movements were responsible for approximately 30% of HPAI H5N6 infections, the identified estimates of poultry density would be interpreted as the associations with the increased poultry‐related activities, including biosecurity breakdowns associated with indirect contacts with HPAIV from wild birds and the sharing of farm inputs such as personnel, feed, and water resources, thereby facilitating the introduction of HPAIV into a farm. In light of the challenges in limiting the establishment of poultry farms in regions where poultry production is in great demand, it is essential to improve farm‐level biosecurity to reduce the risk of HPAI infection of poultry farms already located in the region (Liang et al., 2020).…”

“…However, we considered that the variables including the poultry density and poultry species variables and the spatial effects of the model could partly reflect the effects of network of the livestock-related vehicles. Moreover, given that 30% of the HPAI occurrence was contributed by the vehicles (Yoo et al, 2021), it can be considered that our analysis would demonstrate the epidemiology of HPAI.…”

Genome-associations of extended-spectrum ß-lactamase producing (ESBL) or AmpC producing E. coli in small and medium pig farms from Khon Kaen province, Thailand

“…The acquisition of the same plasmids in different hosts and/or farms might suggest a common environmental compartment that is shared by different farms (e.g., water), other unknown indirect transmission routes [64] or plasmid transmission into the hosts' bacterial flora during transient gut colonization [65]. An alternative explanation of plasmid sharing in multiple farms could be the movement of people and animals between farms colonized with these bacteria and/or plasmids, as observed for other microorganisms [66][67][68]. A recent study highlighting the Thai pig trade network indicated that this network could facilitate the spread of infectious diseases [69].…”

Interpolation of Point Prevalence Rate of the Highly Pathogenic Avian Influenza Subtype H5N8 Second Phase Epidemic in South Korea

“…Previous research studies have highlighted the dynamic behavior of HPAI virus spread, along with the variables that affect the radius of bird culling around the infected zone during the local transmission of avian influenza viruses, although there was a disparity in focusing on the areas that are at high risk. It is crucial to assess high-risk sites based on prior HPAI H5N8 epidemics [ 25 , 26 ]. Inverse distance weighting and kriging approaches were used to predict high-risk locations in South Korea.…”