Spread Of Highly Pathogenic Avian Influenza Research Articles

UK flockdown: A survey of smallscale poultry keepers and their understanding of governmental guidance on highly pathogenic avian influenza (HPAI)

The scale of the current outbreak of highly pathogenic avian influenza (HPAI) due to the A/H5N1 virus in the United Kingdom is unprecedented. In addition to its economic impact on the commercial poultry sector, the disease has devastated wild bird colonies and represents a potential public health concern on account of its zoonotic potential. Although the implementation of biosecurity measures is paramount to reducing the spread of HPAI in domestic and commercial settings, little is known about the attitudes and perspectives of backyard poultry keepers, who often keep their flocks in close proximity to the public. A large nationwide survey of backyard poultry keepers was undertaken in December 2021–March 2022, contemporaneous with the enforcement of an Avian Influenza Prevention Zone (AIPZ) and additional housing measures in England, Scotland and Wales. The survey explored keepers’ understanding of the clinical manifestations of HPAI, compliance with housing and biosecurity measures, attitudes towards obligatory culling on confirmation of HPAI in their flocks, and the potential use of vaccination to control HPAI. Summary statistical analysis of the closed question responses was supplemented with qualitative data analysis and corpus linguistic approaches to draw out key themes and salient patterns in responses to open text questions. Survey responses were received from 1559 small-scale poultry keepers across the United Kingdom. Awareness of the HPAI outbreak was very high (99.0%). The majority of respondents learned of it via social media (53%), with Defra (49.7%), British Hen Welfare Trust (33.8%) and the APHA (22.0%) identified as the principal sources of information. Analysis revealed that backyard keepers lacked knowledge of the clinical signs of avian influenza and legal requirements relating to compliance with biosecurity measures. Some respondents dismissed the seriousness of HPAI and were unwilling to comply with the measures in force. The issue of obligatory culling proved highly emotive, and some expressed a lack of trust in authorities. Most respondents (93.1%) indicated a willingness to pay for vaccination if the option was available. Communications on biosecurity measures that are relevant to large-scale industrial setups are inappropriate for backyard contexts. Understanding the barriers that backyard keepers face is essential if official agencies are to communicate biosecurity information effectively to such groups. Lack of trust in authorities is likely to make elimination of the virus in the UK difficult. We make recommendations for tailoring HPAI-related information for backyard contexts, to aid future HPAI control measures in the UK.

Vaccination against highly pathogenic avian influenza (HPAI): From opposition to acceptance. Proceeding of The First International Avian Influenza Summit, University of Arkansas- October 16-17, 2023”

The emergence of Highly Pathogenic Avian Influenza (HPAI) strains poses a significant threat to both avian populations and human health. Vaccination has been identified as a critical tool in mitigating the spread of HPAI. However, the acceptance and implementation of avian influenza vaccination programs have been met with opposition from various stakeholders, including poultry producers, public health authorities, and consumers. This abstract provides a comprehensive overview of the evolving landscape of HPAI vaccination strategies, tracing the trajectory from initial resistance to widespread acceptance. Initially, concerns surrounding vaccine efficacy, potential adverse effects, and the economic burden associated with large-scale vaccination campaigns led to hesitancy among poultry producers and industry stakeholders. Additionally, public health authorities grappled with challenges related to regulatory approval, vaccine strain selection, and the development of robust surveillance systems. Over time, advancements in vaccine technology and extensive research demonstrating the safety and effectiveness of HPAI vaccines have gradually shifted perceptions. Adopting innovative vaccination strategies, such as vector-based vaccines and recombinant technologies, has addressed previous limitations and bolstered confidence in immunization as a viable control measure. Moreover, collaborative efforts between international organizations, governments, and research institutions have played a pivotal role in establishing standardized vaccine development, distribution, and administration protocols. These endeavors have facilitated harmonizing global strategies and enhanced the preparedness and response mechanisms for potential HPAI outbreaks. Consumer attitudes have also evolved, driven by increased awareness of the public health implications of avian influenza and a growing demand for sustainable and ethically produced poultry products. This shift in consumer sentiment has incentivized industry stakeholders to embrace vaccination as a proactive measure to safeguard both avian welfare and human health. In conclusion, this abstract highlights the transformative journey of HPAI vaccination programs, underscoring the pivotal role of scientific innovation, collaborative partnerships, and evolving consumer perspectives in overcoming initial resistance. As the global community continues to confront emerging infectious diseases, the successful trajectory of HPAI vaccination provides valuable insights into the dynamic interplay between science, policy, and public perception in the face of evolving health challenges.

Using surveillance data for early warning modelling of highly pathogenic avian influenza in Europe reveals a seasonal shift in transmission, 2016–2022

Avian influenza in wild birds and poultry flocks constitutes a problem for animal welfare, food security and public health. In recent years there have been increasing numbers of outbreaks in Europe, with many poultry flocks culled after being infected with highly pathogenic avian influenza (HPAI). Continuous monitoring is crucial to enable timely implementation of control to prevent HPAI spread from wild birds to poultry and between poultry flocks within a country. We here utilize readily available public surveillance data and time-series models to predict HPAI detections within European countries and show a seasonal shift that happened during 2021–2022. The output is models capable of monitoring the weekly risk of HPAI outbreaks, to support decision making.

Live Wild Bird Trade and Sellers’ Biosecurity Risks in Kaduna State, Nigeria

Aims: The first highly pathogenic avian influenza (HPAI) H5N1 outbreak in Africa occurred in Kaduna State, Nigeria and despite possible introduction of H5N1 virus into Nigeria through wild birds; few studies have been undertaken on the risk of live wild bird trade and sellers” biosecurity practices on introduction, spread and maintenance of diseases in the country. This study assessed wild bird trade and sellers” biosecurity risk towards disease surveillance and control in Kaduna State, Nigeria.
 Place and Duration of Study: Live wild bird markets in Kaduna State, Nigeria between March, and May 2012.
 Methodology: Live wildbird markets(LWBMs) biosecurity and sellers’ knowledge, attitudes and practices on HPAI was assessed using biosecurity checklist and structured questionnaire, respectively. Wild bird trade was studied through a market survey in LWBMs.
 Results: All sellers were male and their main source of income was the wild bird trade. Some sellers (22.7%) would report sick birds only when attempted treatment fails. Sellers kept poultry at home (78.9%) with 100% allowing poultry–wild birds contact. Over 31.6% sellers do not wash hands with soap after handling birds. About 86.4% sellers heard of AI with 84.2% hearing from radio. No sellers knew any HPAI clinical sign though 21.1% knew HPAI affects human beings and none believes HPAI affects human beings. Sellers would report HPAI outbreak to reduce losses (38.9%). None of the LWBMs was fenced with birds tied and allowed to move in 25% of LWBMs. Cages were wood/metal while fenced pens constructed from wood/wire mesh with un-cemented floor. No LWBM sourced birds from one reliable source neither were birds separated by species. In 50% of LWBMs, cages were stacked without paper or other materials lined within cages. No LWBM either stored feed in rodent proof containers or had a rodent control program. Other livestock were sold in 75% of LWBMs. Free flying birds interact with wild birds in 75% of LWBMs while free range poultry – wild bird interaction occurred in 25% of LWBMs. No seller wore protective clothing in any LWBM. All markets practice regular cleaning of cages and pens though none disinfects cages regularly. All LWBMs dispose dead birds properly by burning or burying though 25% dispose wild bird manure improperly. Over 75.9% of biosecurity features in LWBMs were risky with 76.2% being risky biosecurity practices and 80% (17/21) due to poor LWBM infrastructures. Food (31.8%), traditional medicine (45.5%) and pets (77.3%) were reported wild birds uses. There was high demand for birds of prey during election years. White stork (11.42%) and geese (9.94%) were the main birds on sale. Threatened and rear wild bird species were being traded in the LWBMs. Over 45% of birds were sourced from 9 foreign countries with majority coming from Chad. Bird prices range was ₦300 ($1.9) to ₦125,000 ($781). Mammals and reptiles were also sold in LWBMs with prices from ₦500 ($3.1) to ₦ 1.2million ($7500). Wild birds on sale in the four LWBMs were valued at ₦6,575,300 ($41,100) comprising of 71.4% of total value of animals (₦9,207,300) on sale.
 Conclusion: Sellers’ biosecurity practices was poor with high biosecurity risk due to low-risk perception. Biosecurity in LWBMs in Kaduna State was poor with high risk to introduction, spread and maintenance of HPAI. Wild bird trade in Kaduna State is linked to the global trade and could be a source for disease introduction into Nigeria. There is need for sellers to be trained on HPAI and other emerging infectious diseases and routine surveillance of EIDs in LWBMs. The wild bird trade should be legalized and regulated.

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

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.

Analyzing Spatial Dependency of the 2016-2017 Korean HPAI Outbreak to Determine the Effective Culling Radius.

Highly pathogenic avian influenza (HPAI) outbreaks are a threat to human health and cause extremely large financial losses to the poultry industry due to containment measures. Determining the most effective control measures, especially the culling radius, to minimize economic impacts yet contain the spread of HPAI is of great importance. This study examines the factors influencing the probability of a farm being infected with HPAI during the 2016–2017 HPAI outbreak in Korea. Using a spatial random effects logistic model, only a few factors commonly associated with a higher risk of HPAI infection were significant. Interestingly, most density-related factors, poultry and farm, were not significantly associated with a higher risk of HPAI infection. The effective culling radius was determined to be two ranges: 0.5–2.2 km and 2.7–3.0 km. This suggests that the spatial heterogeneity, due to local characteristics and/or the characteristics of the HPAI virus(es) involved, should be considered to determine the most effective culling radius in each region. These findings will help strengthen biosecurity control measures at the farm level and enable authorities to quickly respond to HPAI outbreaks with effective countermeasures to suppress the spread of HPAI.

Qualitative Risk Analysis of the Transmission of Highly Pathogenic Avian Influenza (HPAI) H5N1 through Manure Trade in Côte d'Ivoire

The contamination with Highly Pathogenic Avian Influenza (HPAI) H5N1 viruses occurs via the digestive tract following the ingestion of water or food contaminated with droppings of asymptomatic carriers or sick birds. Regarding the local practice of the use of poultry manure as an agricultural fertilizer, this study focuses on the risk of spread of the HPAI through the manure trade pathway in Côte d'Ivoire. For this purpose, epidemiological data and 96 poultry droppings samples were collected from 18 farms. The droppings samples were tested using the real time polymerase chain reaction (RT-PCR). The qualitative risk assessment (QRA) took into account event patterns by integrating all the pathways involved in the spread of HPAI. From the diagnostic test, all the 96 samples tested negative. Further investigations revealed that 74% of the Agnibilékrou farms experienced HPAI outbreaks in the past two years. The main risk factors identified were the movement of people, animals and fomites from one infected area to another. Additionally, the duration of storage of droppings and the distance between stockpiles and farms were potential risk factors. The QRA identified two levels of risk: moderate to high (60%) and low to negligible (40%). The estimated high risk occurs when the dropping is fresh and is low after an optimal period of storage. It is therefore necessary to make storage systematic and mandatory as a measure of treatment before the adoption of other complex measures such as composting and industrial processing.

The Risk of Highly Pathogenic Influenza A Virus Transmission to Turkey Hen Flocks Through Artificial Insemination.

Artificial insemination is a routine practice for turkeys that can introduce pathogens into breeder flocks in a variety of ways. In this manuscript, a risk analysis on the potential transmission of highly pathogenic avian influenza (HPAI) to naïve hens through artificial insemination is presented. A case of HPAI on a stud farm where the potential transmission of the virus to susceptible hens in the 2015 H5N2 HPAI outbreak in Minnesota is described along with documentation of known and potential transmission pathways from the case. The pathways by which artificial insemination might result in the spread of HPAI to susceptible hens were determined by considering which could result in the 1) entry of HPAI virus onto a premises through semen movement; and 2) exposure of susceptible hens to HPAI as a result of this movement. In the reported case, HPAI virus was detected in semen from infected toms, however, transmission of HPAI to naïve hens through semen is unclear since the in utero infectious dose is not known. This means that the early detection of infection might limit but not eliminate the risk of hen exposure. Because of the numerous potential pathways of spread and the close contact with the birds, it is highly likely that if semen from an HPAI-infected tom flock is used, there will be spread of the virus to naïve hens through insemination. If insemination occurs with semen from stud farms in an HPAI control area, receiving hen farms should have restricted movements to prevent outbreak spread in the event that they become infected.

Effects of Spatial Characteristics on the Spread of the Highly Pathogenic Avian Influenza (HPAI) in Korea.

This paper examines the effects of regional characteristics on the spread of the highly pathogenic avian influenza (HPAI) during Korea’s 2016–2017 outbreak. A spatial econometric model is used to determine the effects of regional characteristics on HPAI dispersion using data from 162 counties in Korea. Results indicate the existence of spatial dependence, suggesting that the occurrence of HPAI in a county is significantly influenced by neighboring counties. We found that larger size poultry, including laying hens, breeders, and ducks are significantly associated with a greater incidence of HPAI. Among poultry, we found ducks as the greatest source of the spread of HPAI. Our findings suggest that those regions that are spatially dependent with respect to the spread of HPAI, such as counties that intensively breed ducks, should be the focus of surveillance to prevent future epidemics of HPAI.

Multiple Reassortants of H5N8 Clade 2.3.4.4b Highly Pathogenic Avian Influenza Viruses Detected in South Korea during the Winter of 2020-2021.

During October 2020–January 2021, we isolated a total of 67 highly pathogenic avian influenza (HPAI) H5N8 viruses from wild birds and outbreaks in poultry in South Korea. We sequenced the isolates and performed phylogenetic analysis of complete genome sequences to determine the origin, evolution, and spread patterns of these viruses. Phylogenetic analysis of the hemagglutinin (HA) gene showed that all the isolates belong to H5 clade 2.3.4.4 subgroup B (2.3.4.4b) and form two distinct genetic clusters, G1 and G2. The cluster G1 was closely related to the 2.3.4.4b H5N8 HPAI viruses detected in Europe in early 2020, while the cluster G2 had a close genetic relationship with the 2.3.4.4b H5N8 viruses that circulated in Europe in late 2020. A total of seven distinct genotypes were identified, including five novel reassortants carrying internal genes of low pathogenic avian influenza viruses. Our Bayesian discrete trait phylodynamic analysis between host types suggests that the viruses initially disseminated from migratory waterfowl to domestic duck farms in South Korea. Subsequently, domestic duck farms most likely contributed to the transmission of HPAI viruses to chicken and minor poultry farms, highlighting the need for enhanced, high levels of biosecurity measures at domestic duck farms to effectively prevent the introduction and spread of HPAI.

Surveillance and Sequestration Strategies to Reduce the Likelihood of Transporting Highly Pathogenic Avian Influenza Virus Contaminated Layer Manure.

Movement and land application of manure is a known risk factor for secondary spread of avian influenza viruses. During an outbreak of highly pathogenic avian influenza (HPAI), movement of untreated (i.e., fresh) manure from premises known to be infected is prohibited. However, moving manure from apparently healthy (i.e., clinically normal) flocks may be critical, because some egg-layer facilities have limited on-site storage capacity. The objective of this analysis was to evaluate targeted dead-bird active surveillance real-time reverse transcriptase polymerase chain reaction (rRT-PCR) testing protocols that could be used for the managed movement of manure from apparently healthy egg-layer flocks located in an HPAI control area. We also evaluated sequestration, which is the removal of manure from any contact with chickens, or with manure from other flocks, for a period of time, while the flock of origin is actively monitored for the presence of HPAI virus. We used stochastic simulation models to predict the chances of moving a load of contaminated manure, and the quantity of HPAI virus in an 8 metric ton (8000 kg) load of manure moved, before HPAI infection could be detected in the flock. We show that the likelihood of moving contaminated manure decreases as the length of the sequestration period increases from 3 to 10 days (e.g., for a typical contact rate, with a sample pool size of 11 swabs, the likelihood decreased from 48% to <1%). The total quantity of feces from HPAI-infectious birds in a manure load moved also decreases. Results also indicate that active surveillance protocols using 11 swabs per pool result in a lower likelihood of moving contaminated manure relative to protocols using five swabs per pool. Simulation model results from this study are useful to inform further risk evaluation of HPAI spread through pathways associated with manure movement and further evaluation of biosecurity measures intended to reduce those risks.

Surveillance and sequestration strategies to reduce the likelihood of transporting HPAIV contaminated layer manure.

Movement and land application of manure is a known risk factor for secondary spread of avian influenza (AI) viruses. During an outbreak of highly pathogenic avian influenza (HPAI), movement of untreated (i.e., fresh) manure from premises known to be infected would be prohibited. However, moving manure from apparently healthy (i.e., clinically normal) flocks may become critical, because some egg-layer facilities have limited on-site storage capacity. The objective of this analysis was to evaluate targeted dead-bird active surveillance rRT-PCR (real-time reverse transcriptase polymerase chain reaction) testing protocols that could be used for the managed movement of manure from apparently healthy egg-layer flocks located in a HPAI Control Area. We also evaluated sequestration, which is the removal of manure from any contact with chickens, or with manure from other flocks, for a period of time, while the flock of origin is actively monitored for the presence of HPAI virus. We used stochastic simulation models to predict the chances of moving a load of contaminated manure, and the quantity of HPAI virus in an 8 metric ton (8000 kg) load of manure moved, before HPAI infection would be detected in the flock. We show that the likelihood of moving contaminated manure would decrease as the length of the sequestration period increased from 3 to 10 days (e.g., for a typical contact rate, with a sample pool size of 11 swabs, the likelihood decreased from 48% to <1%). The total quantity of feces from HPAI infectious birds in a manure load moved would also decrease. Results also indicate that active surveillance protocols using 11 swabs per-pool result in a lower likelihood of moving contaminated manure relative to protocols using 5 swabs per pool. Simulation model results from this study are useful to inform further risk evaluation of HPAI spread through pathways associated with the manure movement, and further evaluation of biosecurity measures intended to reduce those risks.

Highly Pathogenic Avian Influenza Clade 2.3.4.4b Subtype H5N8 Virus Isolated from Mandarin Duck in South Korea, 2020.

In October 2020, a highly pathogenic avian influenza (HPAI) subtype H5N8 virus was identified from a fecal sample of a wild mandarin duck (Aix galericulata) in South Korea. We sequenced all eight genome segments of the virus, designated as A/Mandarin duck/Korea/K20-551-4/2020(H5N8), and conducted genetic characterization and comparative phylogenetic analysis to track its origin. Genome sequencing and phylogenetic analysis show that the hemagglutinin gene belongs to H5 clade 2.3.4.4 subgroup B. All genes share high levels of nucleotide identity with H5N8 HPAI viruses identified from Europe during early 2020. Enhanced active surveillance in wild and domestic birds is needed to monitor the introduction and spread of HPAI via wild birds and to inform the design of improved prevention and control strategies.

Biosecurity challenges in the control of avian influenza in Nigeria

Highly Pathogenic Avian Influenza (HPAI) has a devastating impact on the economy especially the poultry industry and it jeopardizes food security and public health. The disease which was first reported in Nigeria in 2006, re-occurred in 2015, 2016, 2018 and 2019. Inspite of the efforts the federal government has put into eradicating Avian Influenza in the country, the re-occurrence of the disease points to challenges of control efforts by stakeholders. Biosecurity challenges confronting poultry farmers and live bird market operators were implicated in new outbreaks and spread of HPAI. A cross-sectional study was carried out by administering open ended questionnaires to poultry farmers and live bird marketers in 12 States that shared boundaries with States affected by HPAI in 2019. Using the thematic style of qualitative analysis and MS Excel 2016, data and information with common denominators and pattern were collated and grouped. The One Health approach was adopted for this study. This was achieved by evaluating the knowledge of the stakeholders on the spread of Avian Influenza (AI), the biosecurity challenges they faced, their recommended solutions and new preventive or control measures they were willing to implement in order to achieve biosecurity against AI outbreak. The live bird marketers' responses showed their major challenge to be poor commitment to implementing already known biosecurity rules (22%), followed by unavailability of funds (13%) and sanitation problems. The poultry farmers struggled with lack of funds for maintenance (32%), and lack of compliance to biosecurity by farm attendants (24%). Both groups jointly recommended alleviating strategies such as the improvement of stakeholder education, supportive financing and the strengthening of animal health legislations. These new insights would benefit the formulation and implementing effective probiosecurity strategies for the control of avian influenza.&#x0D; Keywords: Avian influenza, biosecurity, one health, poultry farms, Nigeria

PAIVS: prediction of avian influenza virus subtype.

Highly pathogenic avian influenza (HPAI) viruses have caused severe respiratory disease and death in poultry and human beings. Although most of the avian influenza viruses (AIVs) are of low pathogenicity and cause mild infections in birds, some subtypes including hemagglutinin H5 and H7 subtype cause HPAI. Therefore, sensitive and accurate subtyping of AIV is important to prepare and prevent for the spread of HPAI. Next-generation sequencing (NGS) can analyze the full-length sequence information of entire AIV genome at once, so this technology is becoming a more common in detecting AIVs and predicting subtypes. However, an analysis pipeline of NGS-based AIV sequencing data, including AIV subtyping, has not yet been established. Here, in order to support the pre-processing of NGS data and its interpretation, we developed a user-friendly tool, named prediction of avian influenza virus subtype (PAIVS). PAIVS has multiple functions that support the pre-processing of NGS data, reference-guided AIV subtyping, de novo assembly, variant calling and identifying the closest full-length sequences by BLAST, and provide the graphical summary to the end users.

Agricultural and geographic factors shaped the North American 2015 highly pathogenic avian influenza H5N2 outbreak.

The 2014–2015 highly pathogenic avian influenza (HPAI) H5NX outbreak represents the largest and most expensive HPAI outbreak in the United States to date. Despite extensive traditional and molecular epidemiological studies, factors associated with the spread of HPAI among midwestern poultry premises remain unclear. To better understand the dynamics of this outbreak, 182 full genome HPAI H5N2 sequences isolated from commercial layer chicken and turkey production premises were analyzed using evolutionary models able to accommodate epidemiological and geographic information. Epidemiological compartmental models embedded in a phylogenetic framework provided evidence that poultry type acted as a barrier to the transmission of virus among midwestern poultry farms. Furthermore, after initial introduction, the propagation of HPAI cases was self-sustainable within the commercial poultry industries. Discrete trait diffusion models indicated that within state viral transitions occurred more frequently than inter-state transitions. Distance and sample size were very strongly supported as associated with viral transition between county groups (Bayes Factor > 30.0). Together these findings indicate that the different types of midwestern poultry industries were not a single homogenous population, but rather, the outbreak was shaped by poultry industries and geographic factors.

Fireworks-like surveillance approach: The case of HPAI H5N1 in wild birds in Europe.

Highly pathogenic avian influenza (HPAI) risk management requires efficient surveillance of the infection in wild birds for early warning purposes. In this study, our aim was to describe the spread of continent-wide infection cases using a fireworks model and therefore improve current surveillance systems. The fireworks model is a metaphor illustrating the spread of HPAI as a point source epizootic. The approach is based on early detection of the outbreak seeds (sparks from the fireworks) and uses a predictive model of the probability of the occurrence of new cases following a seed introduction; this then determines the spatiotemporal perimeter for intense surveillance investigations. For a case study, we used surveillance data on HPAI H5N1 in wild birds across Europe between 2005 and 2010 to describe the outbreaks and determine the success of the case detection used to inform management of the disease. The fireworks description assumes simultaneous introductions of 'seeds' of cases, which then 'explode' in local foci but do not merge into a progressive disease wave. This model fits the data well. Using this predictive approach for HPAI cases in EU countries, we found that the investigation radius needed to achieve a detection level of 90% of new cases after an outbreak ranged from 10km to more than 300km, depending on the outbreak pattern. Based on these findings, the fireworks approach can be a valuable method for identifying the perimeters and risk areas to be targeted for enhanced surveillance. The rationale of the fireworks approach is quite generic and can easily be adapted to different situations and contexts.

Historical and geographical patterns of new HPAIV emergences and association with spatial factors

Historical and geographical patterns of new HPAIV emergences and association with spatial factors

Spatial transmission of H5N2 highly pathogenic avian influenza between Minnesota poultry premises during the 2015 outbreak

The spatial spread of highly pathogenic avian influenza (HPAI) H5N2 during the 2015 outbreak in the U.S. state of Minnesota was analyzed through the estimation of a spatial transmission kernel, which quantifies the infection hazard an infectious premises poses to an uninfected premises some given distance away. Parameters were estimated using a maximum likelihood method for the entire outbreak as well as for two phases defined by the daily number of newly detected HPAI-positive premises. The results indicate both a strong dependence of the likelihood of transmission on distance and a significant distance-independent component of outbreak spread for the overall outbreak. The results further suggest that HPAI spread differed during the later phase of the outbreak. The estimated spatial transmission kernel was used to compare the Minnesota outbreak with previous HPAI outbreaks in the Netherlands and Italy to contextualize the Minnesota transmission kernel results and make additional inferences about HPAI transmission during the Minnesota outbreak. Lastly, the spatial transmission kernel was used to identify high risk areas for HPAI spread in Minnesota. Risk maps were also used to evaluate the potential impact of an early marketing strategy implemented by poultry producers in a county in Minnesota during the outbreak, with results providing evidence that the strategy was successful in reducing the potential for HPAI spread.

Global dynamics of highly pathogenic avian influenza outbreaks in poultry between 2005 and 2016-Focus on distance and rate of spread

Highly pathogenic avian influenza (HPAI) is of major importance for human and animal health because of high morbidity and mortality in poultry and the potential for transmission of this zoonotic pathogen to humans. Knowledge of HPAI epidemiology in avian populations and practical information on the temporal and spatial spread of the disease after introduction into a country is important in order to enhance the capacity of predicting and managing epidemics to minimize the negative impacts on human and animal health. Using data reported to the World Organisation for Animal Health between 2005 and 2017 by 199 countries for 14,129 outbreaks in poultry, we used a spatial and time-series analysis to determine that: (a) During the last 12years, there were two major global peaks in the number of countries affected by HPAI with 23% and 26% of countries affected in 2006 and 2016. (b) Based on the seasonality analysis, spread is the lowest in September, begins to rise in October, and peaks in February. (c) The median distance HPAI outbreaks spread from the index outbreak was 111km, while the median apparent rate of spread of outbreaks was 1.9km/day. (d) In 39% of HPAI events, the disease did not spread beyond the index outbreak and the median maximum spread from the index outbreak per event was 45km. (e) The distance HPAI outbreaks spread from the index outbreak was significantly negatively correlated with the number of outbreaks during the same time period, indicating that the spread of HPAI was lower during global panzootics than during periods of low transmission. These findings are of major importance for veterinary services to design and implement surveillance measures for improving preparedness to minimize the impacts of this disease.