Risk-based surveillance for H5N1 avian influenza virus in wild birds in Great Britain

Recent outbreaks of the H5N1 strain of avian influenza in Europe have highlighted the need for continuous surveillance and early detection to reduce the likelihood of a major outbreak in the commercial poultry industry. In Great Britain (gb), one possible route by which H5N1 could be introduced into domestic poultry is through migratory wild birds from Europe and Asia. Extensive monitoring data on the 24 wild bird species considered most likely to introduce the virus into GB, and analyses of local poultry populations, were used to develop a risk profile to identify the areas where H5N1 is most likely to enter and spread to commercial poultry. The results indicate that surveillance would be best focused on areas of Norfolk, Suffolk, Lancashire, Lincolnshire, south-west England and the Welsh borders, with areas of lower priority in Anglesey, south-west Wales, north-east Aberdeenshire and the Firth of Forth area of Scotland. These areas have significant poultry populations including a large number of free-range flocks, and a high abundance of the 24 wild bird species.     

Risk signals of an influenza pandemic caused by highly pathogenic avian influenza subtype H5N1: spatio-temporal perspectives

Highly pathogenic avian influenza (HPAI) subtype H5N1 is a trans-boundary animal disease that has crossed the animal-human species barrier and over the past decade has had a considerable impact on the poultry industry, wild bird populations and on human health. Understanding the spatio-temporal patterns of H5N1 outbreaks can provide visual clues to the dynamics of disease spread and of areas at risk, and thus improve the cost-effectiveness of disease control and prevention. This study describes the characteristics and investigates the temporal, spatial and space-time dynamics of H5N1 outbreaks in domestic poultry between December 2003 and December 2009 using a global database. The study found that the start date of the epidemic wave was postponed, the duration of the epidemic was prolonged and its magnitude reduced over time, but the disease transmission cycle was not efficiently interrupted. Two 'hot-spot' regions of H5N1 outbreaks were identified: well-documented locations in East and Southeast Asia, as well as a novel location at the boundaries of Europe and Africa, where enhanced surveillance should be conducted. The risk of a pandemic due to H5N1 remains high.     

Risk-based surveillance for avian influenza control along poultry market chains in South China: The value of social network analysis

Over the past two decades, the poultry sector in China went through a phase of tremendous growth as well as rapid intensification and concentration. Highly pathogenic avian influenza virus (HPAIV) subtype H5N1 was first detected in 1996 in Guangdong province, South China and started spreading throughout Asia in early 2004. Since then, control of the disease in China has relied heavily on wide-scale preventive vaccination combined with movement control, quarantine and stamping out. This strategy has been successful in drastically reducing the number of outbreaks during the past 5years. However, HPAIV H5N1 is still circulating and is regularly isolated in traditional live bird markets (LBMs) where viral infection can persist, which represent a public health hazard for people visiting them. The use of social network analysis in combination with epidemiological surveillance in South China has identified areas where the success of current strategies for HPAI control in the poultry production sector may benefit from better knowledge of poultry trading patterns and the LBM network configuration as well as their capacity for maintaining HPAIV H5N1 infection. We produced a set of LBM network maps and estimated the associated risk of HPAIV H5N1 within LBMs and along poultry market chains, providing new insights into how live poultry trade and infection are intertwined. More specifically, our study provides evidence that several biosecurity factors such as daily cage cleaning, daily cage disinfection or manure processing contribute to a reduction in HPAIV H5N1 presence in LBMs. Of significant importance is that the results of our study also show the association between social network indicators and the presence of HPAIV H5N1 in specific network configurations such as the one represented by the counties of origin of the birds traded in LBMs. This new information could be used to develop more targeted and effective control interventions.     

Public health risk from avian influenza viruses

Since 1997, avian influenza (AI) virus infections in poultry have taken on new significance, with increasing numbers of cases involving bird-to-human transmission and the resulting production of clinically severe and fatal human infections. Such human infections have been sporadic and are caused by H7N7 and H5N1 high-pathogenicity (HP) and H9N2 low-pathogenicity (LP) AI viruses in Europe and Asia. These infections have raised the level of concern by human health agencies for the potential reassortment of influenza virus genes and generation of the next human pandemic influenza A virus. The presence of endemic infections by H5N1 HPAI viruses in poultry in several Asian countries indicates that these viruses will continue to contaminate the environment and be an exposure risk with human transmission and infection. Furthermore, the reports of mammalian infections with H5N1 AI viruses and, in particular, mammal-to-mammal transmission in humans and tigers are unprecedented. However, the subsequent risk for generating a pandemic human strain is unknown. More international funding from both human and animal health agencies for diagnosis or detection and control of AI in Asia is needed. Additional funding for research is needed to understand why and how these AI viruses infect humans and what pandemic risks they pose.     

Avian influenza A viruses in birds --an ecological, ornithological and virological view

Avian influenza A viruses (AIV) are the causative agents of the presently most important poultry disease. Ten countries in Asia and several other countries in Eastern Europe suffer high losses from the lethal effects of these viruses of the H5N1 subtype. AIV of other subtypes cause in additional countries severe losses. The threat to health and well-being of the avifauna, domestic poultry and possibly mammals including humans are worldwide of major concern. The European Union reacted with a complete import ban on untreated meat, eggs, poultry products as well as free-living and pet birds. Extensive surveillance of free-living birds and domestic poultry that is maintained in free-range and close to open waters were initiated in an attempt to gather information on the current status of infection with these viruses and to target appropriate countermeasures for the protection of domestic poultry (in-house keeping) and to safeguard food production for humans. Since the monitoring of free-living birds is labour-intensive, costly, and time-consuming, only birds should be included in the monitoring programme that harboured in the past most if not all influenza A viruses. The birds of the order Anatiformes, family Anatidae, subfamilies Anserinae and Anatinae, provided 65.9 % of all avian AIV isolates. The cosmopolitan Common Mallard (Anas platyrhynchos) is the dominant species with the highest rate of isolations among all bird species. Second in frequency is the North-American Blue-winged Teal (Spatula discors). Consequently, free-living anatiform birds of the genera Anas and Spatula should comprise the main focus for the collection of cloacal and pharyngeal swabs. With the likely exception of the most recent H5N1 viruses, signs of disease were not recorded in AIV infected anatiform birds. AIV isolations were definitely less frequently obtained from birds of the orders Phasianiformes (including domestic chickens and turkeys), Charadriiformes (plovers and lapwings), Lariformes (gulls), Columbiformes (pigeons) and Psittaciformes (psittacines) and need less attention in sampling efforts. This review presents also data on taxonomy and most suitable means for isolation and typing of haemagglutinating viruses. The different frequencies of the detection of 16 haemagglutinin (HA) subtypes and 9 subtypes of neuraminidase (NA) surface antigens are composed on the basis of extensive literature retrievals. Both antigens occure in isolates at different frequencies. Only 103 of all 144 possible HA x NA combinations were described so far. The AIV that contain the HA subtypes H3, H4, H6 are most frequently isolated whereas the AIV of the subtypes H5 and H7 were less frequently encountered. All other HAs are rather rare. AIV that possess the NA of the subtypes N2, N1, N8 and N3 are frequent and all other NAs are rarely detected.     

Virological and molecular epidemiological investigations into the role of wild birds in the epidemiology of influenza A/H5N1 in central Thailand

A serological and virological surveillance program to investigate the HPAI H5N1 virus in wild bird populations was undertaken from February 2007 to October 2008. The purpose of the survey was to investigate the infection status in free ranging wild birds in Banglane district, Nakhon Pathom province, central Thailand. Samples from wild birds were collected every two months. Choanal and cloacal swabs, serum and tissue samples were collected from 421 birds comprising 44 species. Sero-prevalence of the virus tested by H5N1 serum neutralization test (using a H5N1 virus clade 1; A/chicken/Thailand/vsmu-3-BKK/2004) was 2.1% (8 out of 385 samples; 95% CI 0.7, 3.5). Species that were antibody positive included rock pigeons (Columba livia), Asian pied starling (Gracupica contra), spotted dove (Streptopelia chinensis), oriental magpie robin (Copsychus saularis), blue-tailed bee-eater (Merops philippinus), myna (Acridotheres spp.), and pond heron (Ardeola spp.). Prevalence by H5N1 virus isolation was 0.5% (2 out of 421 samples; 95% CI 0.0, 1.1); the two H5N1 virus-positive samples were from Asian pied starling (Gracupica contra) and white vented myna (Acridotheres grandis). Positive virological samples were collected in June 2007 while all positive serology samples were collected between May and August except for one sample collected in December 2007. No positive samples were collected in 2008. Molecular studies revealed that the wild bird H5N1 viruses were closely related to poultry viruses isolated in other parts of Thailand. However, there was no poultry H5N1 prevalence study performed in the study site during the time of this wild bird survey. Interpretation of source of virus isolates would include spill-over of H5N1 viruses from contaminated sources due to movement of domestic poultry and/or fomites from other areas; or infection of wild birds within the outbreak locations and then translocation by wild bird movement and interaction with wild birds inhabiting distant locations.     

Susceptibility to and transmission of H5N1 and H7N1 highly pathogenic avian influenza viruses in bank voles (Myodes glareolus)

The study of influenza type A (IA) infections in wild mammals populations is a critical gap in our knowledge of how IA viruses evolve in novel hosts that could be in close contact with avian reservoir species and other wild animals. The aim of this study was to evaluate the susceptibility to infection, the nasal shedding and the transmissibility of the H7N1 and H5N1 highly pathogenic avian influenza (HPAI) viruses in the bank vole (Myodes glareolus), a wild rodent common throughout Europe and Asia. Two out of 24 H5N1-infected voles displayed evident respiratory distress, while H7N1-infected voles remained asymptomatic. Viable virus was isolated from nasal washes collected from animals infected with both HPAI viruses, and extra-pulmonary infection was confirmed in both experimental groups. Histopathological lesions were evident in the respiratory tract of infected animals, although immunohistochemistry positivity was only detected in lungs and trachea of two H7N1-infected voles. Both HPAI viruses were transmitted by direct contact, and seroconversion was confirmed in 50% and 12.5% of the asymptomatic sentinels in the H7N1 and H5N1 groups, respectively. Interestingly, viable virus was isolated from lungs and nasal washes collected from contact sentinels of both groups. The present study demonstrated that two non-rodent adapted HPAI viruses caused asymptomatic infection in bank voles, which shed high amounts of the viruses and were able to infect contact voles. Further investigations are needed to determine whether bank voles could be involved as silent hosts in the transmission of HPAI viruses to other mammals and domestic poultry.     

Assessing the risk of highly pathogenic avian influenza H5N1 transmission through poultry movements in Bali,Indonesia

Indonesia continues to report the highest number of human and poultry cases of highly pathogenic avian influenza H5N1. The disease is considered to be endemic on the island of Bali. Live bird markets are integral in the poultry supply chain on Bali and are important, nutritionally and culturally, for the rural and urban human populations. Due to the lack of biosecurity practiced along the supply chain from producer to live bird markets, there is a need to understand the risks associated with the spread of H5N1 through live bird movements for effective control. Resources to control H5N1 in Indonesia are very limited and cost effective strategies are needed. We assessed the probability a live bird market is infected through live poultry movements and assessed the effects of implementing two simple and low cost control measures on this risk. Results suggest there is a high risk a live bird market is infected (0.78), and risk mitigation strategies such as detecting and removing infected poultry from markets reduce this risk somewhat (range 0.67–0.76). The study demonstrates the key role live poultry movements play in transmitting H5N1 and the need to implement a variety of control measures to reduce disease spread.     

Molecular characterization of the hemagglutinin and neuraminidase genes of H5N1 influenza A viruses isolated from poultry in Vietnam from 2004 to 2005

Highly pathogenic H5N1 avian influenza A viruses have been spreading among domestic poultry, wild aquatic birds, and humans in many Asian countries since 2003. The largest number of patients, to date, infected with the H5N1 viruses are in Vietnam, where these viruses continue to cause outbreaks in domestic poultry. Here, we molecularly characterized the hemagglutinin and neuraminidase genes of nine H5N1 viruses isolated between January 2004 and August 2005 from domestic poultry in Vietnam. We found that several groups of highly pathogenic H5N1 avian influenza viruses are circulating among these birds, which suggests that H5N1 viruses of different lineages have been introduced into Vietnam multiple times.     

Molecular epidemiology of avian influenza viruses circulating among healthy poultry flocks in farms in northern Vietnam

Repeated epizootics of highly pathogenic avian influenza (HPAI) virus subtype H5N1 were reported from 2003 to 2005 among poultry in Vietnam. More than 200 million birds were killed to control the spread of the disease. Human cases of H5N1 infection have been sporadically reported in an area where repeated H5N1 outbreaks among birds had occurred. Subtype H5N1 strains are established as endemic among poultry in Vietnam, however, insights into how avian influenza viruses including the H5N1 subtype are maintained in endemic areas is not clear. In order to determine the prevalence of different avian influenza viruses (AIVs), including H5N1 circulating among poultry in northern Vietnam, surveillance was conducted during the years 2006-2009. A subtype H5N1 strain was isolated from an apparently healthy duck reared on a farm in northern Vietnam in 2008 and was identified as an HPAI. Although only one H5N1 virus was isolated, it supports the view that healthy domestic ducks play a pivotal role in maintaining and transmitting H5N1 viruses which cause disease outbreaks in northern Vietnam. In addition, a total of 26 AIVs with low pathogenicity were isolated from poultry and phylogenetic analysis of all the eight gene segments revealed their diverse genetical backgrounds, implying that reassortments have occurred frequently among strains in northern Vietnam. It is, therefore, important to monitor the prevalence of influenza viruses among healthy poultry between epidemics in an area where AIVs are endemic.     

Origin and evolution of highly pathogenic H5N1 avian influenza in Asia

Outbreaks of highly pathogenic avian influenza caused by H5N1 viruses were reported almost simultaneously in eight neighbouring Asian countries between December 2003 and January 2004, with a ninth reporting in August 2004, suggesting that the viruses had spread recently and rapidly. However, they had been detected widely in the region in domestic waterfowl and terrestrial poultry for several years before this, and the absence of widespread disease in the region before 2003, apart from localised outbreaks in the Hong Kong Special Autonomous Region (SAR), is perplexing. Possible explanations include limited virus excretion by domestic waterfowl infected with H5N1, the confusion of avian influenza with other serious endemic diseases, the unsanctioned use of vaccines, and the under-reporting of disease as a result of limited surveillance. There is some evidence that the excretion of the viruses by domestic ducks had increased by early 2004, and there is circumstantial evidence that they can be transmitted by wild birds. The migratory birds from which viruses have been isolated were usually sick or dead, suggesting that they would have had limited potential for carrying the viruses over long distances unless subclinical infections were prevalent. However, there is strong circumstantial evidence that wild birds can become infected from domestic poultry and potentially can exchange viruses when they share the same environment. Nevertheless, there is little reason to believe that wild birds have played a more significant role in spreading disease than trade through live bird markets and movement of domestic waterfowl. Asian H5N1 viruses were first detected in domestic geese in southern China in 1996. By 2000, their host range had extended to domestic ducks, which played a key role in the genesis of the 2003/04 outbreaks. The epidemic was not due to the introduction and spread of a single virus but was caused by multiple viruses which were genotypically linked to the Goose/GD/96 lineage via the haemagglutinin gene. The H5N1 viruses isolated from China, including the Hong Kong SAR, between 1999 and 2004 had a range of genotypes and considerable variability within genotypes. The rising incidence and widespread reporting of disease in 2003/04 can probably be attributed to the increasing spread of the viruses from existing reservoirs of infection in domestic waterfowl and live bird markets leading to greater environmental contamination. When countries in the region started to report disease in December 2003, others were alerted to the risk and disease surveillance and reporting improved. The H5N1 viruses have reportedly been eliminated from three of the nine countries that reported disease in 2003/04, but they could be extremely difficult to eradicate from the remaining countries, owing to the existence of populations and, possibly, production and marketing sectors, in which apparently normal birds harbour the viruses.     

Characterization of H5N1 influenza viruses isolated from migratory birds in Qinghai province of China in 2006

Avian influenza H5N1 viruses pose a significant threat to human health because of their ability to infect humans directly. In the paper, three highly pathogenic H5N1 influenza viruses were isolated from three species of migratory birds in Qinghai Province of China in 2006. The analysis of the genome sequences indicated that the three isolates shared high homology with each other (94% to 99%). Three isolates shared a common ancestor and were closest to strains isolated from Qinghai and Siberia in 2005, but distinct from poultry viruses found in Southeast Asia. In experimental infection, all three viruses were highly pathogenic to chickens and mice. The results suggest that highly pathogenic avian influenza H5N1 viruses still exist in the migratory birds and could spread to other regions with wild bird migration.     

Putative human and avian risk factors for avian influenza virus infections in backyard poultry in Egypt

Highly pathogenic influenza A virus subtype H5N1 causes significant poultry mortality in the six countries where it is endemic and can also infect humans. Egypt has reported the third highest number of poultry outbreaks (n = 1084) globally. The objective of this cross-sectional study was to identify putative risk factors for H5N1 infections in backyard poultry in 16 villages in Damietta, El Gharbia, Fayoum, and Menofia governorates from 2010–2012. Cloacal and tracheal swabs and serum samples from domestic (n = 1242) and wild birds (n = 807) were tested for H5N1 via RT-PCR and hemagglutination inhibition, respectively. We measured poultry rearing practices with questionnaires (n = 306 households) and contact rates among domestic and wild bird species with scan sampling. Domestic birds (chickens, ducks, and geese, n = 51) in three governorates tested positive for H5N1 by PCR or serology. A regression model identified a significant correlation between H5N1 in poultry and the practice of disposing of dead poultry and poultry feces in the garbage (F = 15.7, p < 0.0001). In addition, contact between domestic and wild birds was more frequent in villages where we detected H5N1 in backyard flocks (F = 29.5, p < 0.0001).     

Infectious dose‐dependent accumulation of live highly pathogenic avian influenza H5N1 virus in chicken skeletal muscle—implications for public health

Highly pathogenic avian influenza viruses (HPAIV) of H5N1 subtype are a major global threat to poultry and public health. Export of poultry products, such as chicken and duck meat, is a known source for the cross‐boundary spread of HPAI H5N1 viruses. Humans get infected with HPAI H5N1 viruses either by close contact with infected poultry or through consumption of fresh/undercooked poultry meat. Skeletal muscle is the largest soft tissue in chicken that has been shown to contain virus during systemic HPAIV infection and supports productive virus infection. However, the time between infection of a chicken with H5N1 virus and presence of virus in muscle tissue is not yet known. Further, it is also not clear whether chicken infected with low doses of H5N1 virus that cause non‐fatal subclinical infections continue to accumulate virus in skeletal muscle. We investigated the amount and duration of virus detection in skeletal muscle of chicken experimentally infected with different doses (10², 10³ and 10⁴ EID₅₀) of a HPAI H5N1 virus. Influenza viral antigen could be detected as early as 6 hr after infection and live virus was recovered from 48 hr after infection. Notably, chicken infected with lower levels of HPAI H5N1 virus (i.e., 10² EID₅₀) did not die acutely, but continued to accumulate high levels of H5N1 virus in skeletal muscle until 6 days post‐infection. Our data suggest that there is a potential risk of human exposure to H5N1 virus through meat from clinically healthy chicken infected with a low dose of virus. Our results highlight the need to implement rigorous monitoring systems to screen poultry meat from H5N1 endemic countries to limit the global spread of H5N1 viruses.     

Highly pathogenic H5N1 avian influenza virus: Cause of the next pandemic?

Since 1997, when human infections with a highly pathogenic (HP) avian influenza A virus (AIV) subtype H5N1 – previously infecting only birds – were identified in a Hong Kong outbreak, global attention has focused on the potential for this virus to cause the next pandemic. From December 2003, an unprecedented H5N1 epizootic in poultry and migrating wild birds has spread across Asia and into Europe, the Middle East, and Africa. Humans in close contact with sick poultry and on rare occasion with other infected humans, have become infected. As of early March 2007, 12 countries have reported 167 deaths among 277 laboratory-confirmed human infections to WHO. WHO has declared the world to be in Phase 3 of a Pandemic Alert Period. This paper reviews the evolution of HP AIV H5N1, molecular changes that enable AIVs to infect and replicate in human cells and spread efficiently from person-to-person, and strategies to prevent the emergence of a pandemic virus.     

Genetic relationship of H3 subtype avian influenza viruses isolated from domestic ducks and wild birds in Korea and their pathogenic potential in chickens and ducks

The H3 subtype avian influenza virus (AIV) is one of the most frequently isolated subtypes in domestic ducks, live poultry markets, and wild birds in Korea. In 2002-2009, a total of 45 H3 subtype AIVs were isolated from the feces of clinically normal domestic ducks (n=28) and wild birds (n=17). The most prevalent subtypes in domestic ducks were H3N2 (35.7%), H3N6 (35.7%), H3N8 (25.0%), and H3N1 (3.6%, novel subtype in domestic duck in Korea). In contrast, H3N8 (70.6%) is the most prevalent subtype in wild birds in Korea. In the phylogenetic analysis, HA genes of the Korean H3 AIVs were divided into 3 groups (Korean duck, wild bird 1, and wild bird 2) and all viruses of duck origin except one were clustered in a single group. However, other genes showed extensive diversity and at least 17 genotypes were circulating in domestic ducks in Korea. When the analysis expanded to viruses of wild bird origin, the genetic diversity of Korean H3 AIVs became more complicated. Extensive reassortments may have occurred in H3 subtype influenza viruses in Korea. When we inoculated chickens and ducks with six selected viruses, some of the viruses replicated efficiently without pre-adaptation and shed a significant amount of viruses through oropharyngeal and cloacal routes. This raised concerns that H3 subtype AIV could be a new subtype in chickens in Korea. Continuous surveillance is needed to prepare the advent of a novel subtype AIV in Korea.     

Effect of species,breed and route of virus inoculation on the pathogenicity of H5N1 highly pathogenic influenza (HPAI) viruses in domestic ducks

H5N1 highly pathogenic avian influenza (HPAI) viruses continue to be a threat to poultry in many regions of the world. Domestic ducks have been recognized as one of the primary factors in the spread of H5N1 HPAI. In this study we examined the pathogenicity of H5N1 HPAI viruses in different species and breeds of domestic ducks and the effect of route of virus inoculation on the outcome of infection. We determined that the pathogenicity of H5N1 HPAI viruses varies between the two common farmed duck species, with Muscovy ducks (Cairina moschata) presenting more severe disease than various breeds of Anas platyrhynchos var. domestica ducks including Pekin, Mallard-type, Black Runners, Rouen, and Khaki Campbell ducks. We also found that Pekin and Muscovy ducks inoculated with two H5N1 HPAI viruses of different virulence, given by any one of three routes (intranasal, intracloacal, or intraocular), became infected with the viruses. Regardless of the route of inoculation, the outcome of infection was similar for each species but depended on the virulence of the virus used. Muscovy ducks showed more severe clinical signs and higher mortality than the Pekin ducks. In conclusion, domestic ducks are susceptible to H5N1 HPAI virus infection by different routes of exposure, but the presentation of the disease varied by virus strain and duck species. This information helps support the planning and implementation of H5N1 HPAI surveillance and control measures in countries with large domestic duck populations.     

中国H5N1亚型高致病性禽流感病毒抗原变异株的鉴定分析

对引起中国2006年山西、宁夏2省(区)H5N1亚型禽流感疫情的代表毒株——A/chicken/Shanxi/2/2006(H5N1)(CK/SX/06)进行了全面研究。结果表明该病毒具有高致病性禽流感病毒(HPAIV)特征,基因组序列分析发现其8个基因片段与中国传统H5N1亚型禽流感病毒GS/GD/1/96(H5N1)存在较大差异,属于新的基因型——山西鸡型;抗原性分析结果表明其在抗原性方面与GS/GD/1/96同样存在较大变异,将其命名为"山西鸡型"抗原变异株;以106EID50.0.1 mL-1剂量将该病毒经鼻腔接种4周龄SPF鸭以评价其对水禽的感染能力,结果表明其不感染鸭;常规方法接种BALB/c小鼠以评价其对哺乳动物的感染和致病能力,结果表明其能感染小鼠,但不引起死亡,呈低致病力。说明该类型高致病性H5N1 HPAIV目前仅危害鸡,不具备感染水禽的能力,感染哺乳动物但不致死。该类型病毒的出现与流行为中国禽流感的免疫与防制提出新的课题。     

Chinese poultry farmers' decision‐making for avian influenza prevention: a qualitative analysis

Poultry farmers faced dual risk when mutant avian influenza (AI) virus showed the zoonotic characteristics. A/H5N1 and A/H7N9 were two dominant AI virus strains that have captured the attention of the public over the years for they have been reported to bring about greater loss to poultry and human, respectively. Previous studies mainly used quantitative methods investigating either the means that poultry farmers adopted for protecting their poultry against A/H5N1 infection or the poultry farmers' self‐protective behaviours against A/H7N9 infection. We sought insights into the underlying factors influencing Chinese poultry farmers' protective behaviours in response to the dual risk of AI by a qualitative way. Semi‐structured in‐depth interviews were conducted with 25 Chinese chicken farmers recruited by purposive sampling between November 2016 and May 2017, the peak season of AI. All interviews were audio‐taped, transcribed and analysed using a grounded theory approach. From participants' experiences, we revealed five main themes: Measures adopted for protecting poultry and farmers, Emotional response to the AI epidemic, Perceived risk of AI, Perceived effectiveness of the preventive measures adopted and Perceived self‐efficacy to take preventive measures. The information of AI outbreak directly triggered Chinese chicken farmers' emotional response and thereafter preventive actions. Compared to the perceived risk of poultry infection with A/H5N1 which mainly connected to economic loss, participants perceived much lower risk of human infection with A/H7N9. AI epidemic information played a key role triggering poultry farmers' response behaviours. Chinese poultry farmers weighted more attention on the risk of poultry infection which was highly associated with economic losses. The government should build and improve an early AI warning and information transmission network to poultry farmers. Further reinforcement of related self‐protective and preventive knowledge training towards poultry farmers is necessary.