H5N1 Surveillance Research Articles

Unexpected Delayed Incursion of Highly Pathogenic Avian Influenza H5N1 (Clade 2.3.4.4b) Into the Antarctic Region.

The current highly pathogenic avian influenza H5N1 panzootic is having substantial impacts on wild birds and marine mammals. Following major and widespread outbreaks in South America, an incursion to Antarctica occurred late in the austral summer of 2023/2024 and was confined to the region of the Antarctic Peninsula. To infer potential underlying processes, we compiled H5N1 surveillance data from Antarctica and sub-Antarctic Islands prior to the first confirmed cases.

Investigation of a Highly Pathogenic Avian Influenza Outbreak in a Poultry Farm, Dhamrai, Bangladesh, 2017: a One Health Approach

In January 2017, a highly pathogenic avian influenza (HPAI) A virus killed 732 chickens in a farm in Dhamrai, Bangladesh. An investigation assessed transmission of the virus from chickens to farmworkers. Contacts were farmworkers with direct exposure to affected chickens. We interviewed all suspected cases, conducted an active case finding for human cases at the implicated farm and local clinics, and actively searched for carcasses of wild and domestic birds within two kilometers of the implicated farm. All contacts were asymptomatic and had buried dead poultry; 70% touched dead poultry and 29% used protective gloves while working. Nasal and throat swabs were negative for influenza A and B viruses (subtyped for M-gene positive influenza A viruses by PCR and seasonal H3, H1N1 pdm09, and avian H5/H7/H9). The virus was probably introduced to the farm when ducks from the farm were taken to a live bird market and unsold ducks were returned to the farm. While farmworkers were exposed to the infected chickens, there was no evidence of the virus being transmitted to workers. We recommend starting H5N1 surveillance in live bird markets to monitor HPAI.

National surveillance and control costs for highly pathogenic avian influenza H5N1 in poultry: A benefit-cost assessment for a developing economy, Nigeria

We conducted benefit-cost analysis of outbreak and surveillance costs for HPAI H5N1in poultry in Nigeria. Poultry's death directly cost US$ 939,734.0 due to outbreaks. The integrated disease surveillance and response originally created for comprehensive surveillance and laboratory investigation of human diseases was adapted for HPAI H5N1 in poultry. Input data were obtained from the field, government documents and repositories and peer-reviewed publications. Actual/forecasted bird numbers lost were integrated into a financial model and estimates of losses were calculated. Costs of surveillance as alternative intervention were determined based on previous outbreak control costs and outputs were generated in SurvCost® with sensitivity analyses for different scenarios.Uncontrolled outbreaks will lead to loss of over US$ 2.2 billion annually in Nigeria with 47.8% of the losses coming from eggs. The annual cost of all animal related health activities was <US$ 99.0 million, only one-third of this amount was linked with H5N1 surveillance and response activities. Recurrent cost was 96.2% of the total surveillance and response costs, and 31.0% of the HPAI surveillance cost was spent on personnel with 3.8% as capital cost. Cost-wisely, routine monitoring and surveillance for HPAI are 68 times more cost effective than to do nothing. Assuming that successful control and eradication of HPAI H5N1 is partially attributable to H5N1 surveillance and response, a quarter or half of the success will result in 17 or 34 times more benefits. Although animal surveillance and response activities for avian influenza appeared expensive, their implementation are economically cost beneficial for developing countries.

The Evidence of Clade 7.1 Avian Influenza Virus (H5N1) in Qinghai Lake

The highly pathogenic influenza A virus subtype H5N1 spread throughout Asia since 2003, reached to Europe in 2005, and the Middle East, as well as Africa and caused a global concern for a potential pandemic threat last decade. A Clade 2.3.2 H5N1 virus became dominate in the Qinghai Lake region in 2009 with sporadic mammal cases of infection and transferred to Russia and Europe through wild migratory birds. Currently, HPAI H5N1 of clades 2.3.4, 2.3.2, and 7 are the dominant co-circulating H5N1 viruses in poultry in Asia. 2.3.2 Clade is dominant in wild birds through the world whereas there is no evident data about Clade 7 circulation in wild birds. We detected HPAI H5N1 virus of Clade 7.1 in Qinghai Lake, that closely related to Shanxi-like and Vietnam viruses co-circulating in poultry. This is the first report of Clade 7.1 H5N1 in wild birds. Based on phylogenetic analyses, the virus can be originated from Clade 7.1 virus gene pool that spread in Vietnam and Chinese poultry and could spread with migratory birds to Qinghai Lake. The Qinghai Lake continues to be significant hotspot for H5N1 surveillance since the regular outbreaks occurred there in wild birds and mammals. Based on these facts and findings, the related researchers should pay more attention to the Qinghai Lake basin as significant hotspot for H5N1 avian influenza surveillance since the regular H5N1 outbreaks occurred there in wild birds with sporadic mammal cases of infection.

Avian Influenza H5N1 Surveillance and its Dynamics in Poultry in Live Bird Markets, Egypt.

H5N1, a highly pathogenic avian influenza (H5N1 HPAI), is an endemic disease that is significant for public health in Egypt. Live bird markets (LBMs) are widespread in Egypt and play an important role in HPAI disease dynamics. The aim of the study was to evaluate the H5N1 HPAI prevalence in representative LBMs from 2009 to 2014, assess the effects of other variables and evaluate past outbreaks and human cases. It was found that ducks and geese are high-risk species and that the prevalence of H5N1 HPAI was higher immediately after the political crises of 2011. The end of a calendar year (June to December) was a high-risk period for positive samples, and the risk in urban LBMs was twice the risk in rural LBMs. Winter and political unrest was associated with higher H5N1 HPAI prevalence. Both human and poultry populations will continue to rise in Egypt, so continued poultry outbreaks are likely to be linked to more human cases. LBMs will continue to play a role in the dynamics of poultry disease in Egypt, and there is a need to reorganize markets in terms of biosecurity and traceability. It may also be beneficial to reduce inter-governorate inter-regional movements associated with poultry trade through promotion of regional trade or in the alternative provide sanitary features along the poultry market chain to reduce the speed of H5N1 HPAI infections. Policy formulation, design and enforcement must be pro-poor, and consideration of the sociocultural and economic realities in Egypt is important. The LBMs provide ideal platforms to carry out sound surveillance plans and mitigate zoonotic risks of H5N1 HPAI to humans.

Collective resistance to HPAI H5N1 surveillance in the Thai cockfighting community: Insights from a social anthropology study

Farmers may organize themselves to collectively manage risks such as animal diseases. Our study shows some evidence of such organization among fighting cock owners in Thailand. Fighting cocks were specifically targeted by HPAI (Highly Pathogenic Avian Influenza) H5N1 surveillance and control measures in Thailand because they were thought to pose a high risk of spreading diseases. In this work, we used a social-anthropological approach to gain an inside view of the issues associated with HPAI H5N1 surveillance in the cockfighting community in Thailand. Based on a qualitative analysis of data collected through in-depth interviews and observation of cockfighters’ practices, we found that fighting cock owners share a sense of belonging to the same community based on a common culture, values, interests, practices, and internal rules, including rules to manage poultry diseases. During the HPAI H5N1 outbreaks, these rules may have contributed to mitigating the potential risk associated with the intense movements of fighting cocks inside the country. Nevertheless, this community, despite the high awareness and know-how of its members regarding poultry diseases, has shown a strong reluctance to comply with HPAI surveillance programs. We suggest that this reluctance is due to important gaps between the logic and rationales underlying surveillance and those associated with cockfighting activities. Our study highlights the need for multi and trans-disciplinary research involving the social sciences to analyze interactions between stakeholders and the collective actions implemented by communities to face risks.

Bird to human transmission biases and vaccine escape mutants in H5N1 infections.

BackgroundThe avian influenza A H5N1 virus occasionally infects humans, with high mortality rates. Although all current human infections are from avian-to-human transmission, it has been shown that H5N1 can be evolved to transmit between mammals, and is therefore a pandemic threat. For H5N1 surveillance, it is of interest to identify the avian isolates most likely to infect humans. In this study, we develop a method to identify mutations significantly associated with avian to human transmission.MethodUsing protein sequences for the surface glycoprotein hemagglutinin from avian and human H5N1 isolates in China, Egypt, and Indonesia from the years 1996–2011, we used Principle Component Analysis and a Maximum Likelihood Multinomial method to identify mutations associated with avian to human transmission. In each geographic region, transmission bias residues were identified using two signatures: a) significantly different amino-acid frequencies in human isolates compared to avian isolates from the same year, and b) significantly low probability of neutral evolution of the human isolates from the avian viral pool of the previous year.ResultsIn each geographic region, we find specific transmission bias mutations associated with human infections. These mutations are located in antigenic regions and receptor binding, glycosylation and polybasic cleavage sites of HA. We show that human isolates derive from a limited, subset of the avian pool characterized by geography specific mutations. In Egypt, two of three PCA clusters have very few human isolates but are highly enriched in mutations associated with a vaccine escape mutant H5N1 avian sub-clade that is known to be resistant to the Mexican H5N2 vaccine Furthermore, at these transmission bias associated residues, the mutations characteristic of these two clusters are distinct from those associated with the cluster enriched in human isolates, suggesting that vaccine resistant avian strains are unable to infect humans. Our results are relevant for surveillance and vaccination strategies for human H5N1 infections.

Characterization of a highly pathogenic H5N1 avian influenza virus isolated from ducks in Eastern China in 2011

This study describes the characterization of seven H5N1 avian influenza viruses from domestic ducks in Eastern China in 2011. Phylogenetic analysis showed these viruses were closely related to an H5N1 virus circulating in wild birds in Hong Kong. Some characteristics of these viruses were similar to those of an H5N1 strain that circulated in China and Vietnam (2003-2004). The virulence of three isolates was examined in chickens and mice, and they were found to be highly pathogenic in chickens but showed low pathogenicity in mice. These results suggest that continued H5N1 surveillance in poultry should be used as an early warning system for avian influenza outbreaks.

The Effect of Swab Sample Choice on the Detection of Avian Influenza in Apparently Healthy Wild Ducks

Historically, avian influenza viruses have been isolated from cloacal swab specimens, but recent data suggest that the highly pathogenic avian influenza (HPAI) H5N1 virus can be better detected from respiratory tract specimens. To better understand how swab sample type affects the detection ability of low pathogenic avian influenza (LPAI) viruses we collected and tested four swab types: oropharyngeal swabs (OS), cloacal swabs (CS), the two swab types combined in the laboratory (LCS), and the two swab types combined in the field (FCS). A total of 1968 wild waterfowl were sampled by each of these four methods and tested for avian influenza virus using matrix gene reverse-transcription (RT)-PCR. The highest detection rate occurred with the FCS (4.3%) followed by the CS (4.0%). Although this difference did not achieve traditional statistical significance, Bayesian analysis indicated that FCS was superior to CS with an 82% probability. The detection rates for both the LCS (2.4%) and the OS (0.4%) were significantly different from the FCS. In addition, every swab type that was matrix RT-PCR positive was also tested for recovery of viable influenza virus. This protocol reduced the detection rate, but the ordering of swab types remained the same: 1.73% FCS, 1.42% CS, 0.81% LCS, and 0% OS. Our data suggest that the FCS performed at least as well as any other swab type for detecting LPAI viruses in the wild ducks tested. When considering recent studies showing that HPAI H5N1 can be better detected in the respiratory tract, the FCS is the most appropriate sample to collect for HPAI H5N1 surveillance while not compromising LPAI studies.

Quantum‐dots‐based fluoroimmunoassay for the rapid and sensitive detection of avian influenza virus subtype H5N1

The continuous spread of highly pathogenic avian influenza virus (AIV) subtype H5N1 is threatening the poultry industry and human health worldwide. Rapid and sensitive diagnostic methods are required for the H5N1 surveillance. In this study, the fluorescent (FL) probe of CdTe quantum dots (QDs) was designed using covalently linked rabbit anti-AIV H5N1 antibody. Based on these QD-antibody conjugates, a novel sandwich FL-linked immunosorbent assay (sFLISA) was developed for H5N1 viral antigen detection. The sFLISA allowed for H5N1 viral antigen determination in a linear range of 8.0 × 10(-3) to 5.1 × 10(-1) μg mL(-1) with the limit of detection (LOD) of 1.5 × 10(-4) μg mL(-1) . In comparison with virus isolation for 103 clinic samples, the sensitivity and specificity of sFLISA were found to be 93.6 and 91.1% respectively. The sFLISA supplied a novel approach to rapid and sensitive detection of AIV subtype H5N1 and showed great potential for biological applications in immunoassays.

Evaluation of effectiveness and efficiency of wild bird surveillance for avian influenza

This study aimed to assess which method of wild waterbird surveillance had the greatest probability of detecting highly pathogenic avian influenza (HPAI) H5N1 during a period of surveillance activity, the cost of each method was also considered. Lake Constance is a major wintering centre for migratory waterbirds and in 2006 it was the site of an HPAI H5N1 epidemic in wild birds. Avian influenza surveillance was conducted using harmonised approaches in the three countries around the lake, Austria, Germany and Switzerland, from 2006–2009. The surveillance consisted of testing birds sampled by the following methods: live birds caught in traps, birds killed by hunters, birds caught in fishing nets, dead birds found by the public and catching live Mute Swans (Cygnus olor); sentinel flocks of Mallards (Anas platyrhynchos) were also used. Scenario tree analysis was performed including sensitivity analysis, followed by assessment of cost-effectiveness. Results indicated that if HPAI H5N1 was present at 1% prevalence and assuming HPAI resulted in bird mortality, sampling dead birds found by the public and sentinel surveillance were the most sensitive approaches despite residual uncertainty over some parameters. The uncertainty over the mortality of infected birds was an influential factor. Sampling birds found dead was most cost-effective, but strongly dependent on mortality and awareness of the public. Trapping live birds was least cost-effective. Based on our results, we recommend that future HPAI H5N1 surveillance around Lake Constance should prioritise sentinel surveillance and, if high mortality is expected, the testing of birds found dead.

Evaluation of a positive marker of avian influenza vaccination in ducks for use in H5N1 surveillance

Control measures for H5N1 avian influenza involve increased biosecurity, monitoring, surveillance and vaccination. Subclinical infection in farmed ducks is important for virus persistence. In major duck rearing countries, homologous H5N1 vaccines are being used in ducks, so sero-surveillance using H5- or N1-specific antibody testing cannot identify infected flocks. An alternative is to include a positive marker for vaccination. Testing for an antibody response to the marker would confirm approved vaccine use. Concurrent testing for H5 antibody responses would determine levels adequate for protection or indicate recent infection, with an anamnestic H5 antibody response requiring further virological investigation. In this study, we have evaluated the use of a TT marker in ducks given avian influenza vaccination. Wild or domestic ducks were tested for antibodies against TT and all 463 ducks were negative. High levels of TT-specific antibodies, produced in twice-TT vaccinated Muscovy ducks, persisted out to 19 weeks. There was no interference by inclusion of TT in an inactivated H6N2 vaccine for H6- or TT-seroconversion. Thus TT is a highly suitable exogenous marker for avian influenza vaccination in ducks and allows sero-surveillance in countries using H5N1 vaccination.

Fowl Plague and Newcastle Disease

Farmers may organize themselves to collectively manage risks such as animal diseases. Our study shows some evidence of such organization among fighting cock owners in Thailand. Fighting cocks were specifically targeted by HPAI (Highly Pathogenic Avian Influenza) H5N1 surveillance and control measures in Thailand because they were thought to pose a high risk of spreading diseases. In this work, we used a social-anthropological approach to gain an inside view of the issues associated with HPAI H5N1 surveillance in the cockfighting community in Thailand. Based on a qualitative analysis of data collected through in-depth interviews and observation of cockfighters’ practices, we found that fighting cock owners share a sense of belonging to the same community based on a common culture, values, interests, practices, and internal rules, including rules to manage poultry diseases. During the HPAI H5N1 outbreaks, these rules may have contributed to mitigating the potential risk associated with the intense movements of fighting cocks inside the country. Nevertheless, this community, despite the high awareness and know-how of its members regarding poultry diseases, has shown a strong reluctance to comply with HPAI surveillance programs. We suggest that this reluctance is due to important gaps between the logic and rationales underlying surveillance and those associated with cockfighting activities. Our study highlights the need for multi and trans-disciplinary research involving the social sciences to analyze interactions between stakeholders and the collective actions implemented by communities to face risks.