Pathogenic Outbreaks Research Articles

Effects of Highly Pathogenic Avian Influenza H5N1 Outbreak in Nepal from Financial and Social Perspectives: A Case Study

The outbreaks of highly pathogenic avian influenza (HPAI) H5N1 have serious public health, economic and social implications. After the first two report of HPAI H5N1 outbreak in Nepal in Jhapa in 2009, a third outbreak was reported in Pokhara the following year where more than 11,000 birds were culled to control the disease. However, the financial and social effects of the Pokhara bird flu outbreak were never assessed. The objectives of this study were to evaluate the local financial and social effects of HPAI H5N1 outbreak in Pokhara and to understand farmers and consumers perceptions on bird flu and the control measures implemented by the government. A total of 200 people including poultry farmers, butchers, veterinary drug dealers, feed suppliers, and consumers were interviewed using the semi-structured questionnaire. The result showed that the direct loss of Pokhara bird flu outbreak from the culling of birds was more than 4.5 million Nepali rupees. The small scale commercial and backyard farmers and the butchers were the most affected from this outbreak. A large proportion of the consumers temporarily stopped to consume chicken meat and shifted to other meat sources. Most of the participants in this study had at least heard about the bird flu. The farmers were unhappy by the compensation provided by the government and perceived that the government control efforts were not satisfactory and were provided little assistance for their rehabilitation. In conclusion, there was a momentary local financial and social effect of the Pokhara bird flu outbreak which may not very important from the macroeconomic point of view but is important for the affected small-scale farmers and the butchers. It is recommended that the government review their policy and provide small scale commercial and backyard farmer a compensation that is closer to the market price and promote largescale poultry farmers to go for insurance.

Estimating Risk to Humans Exposed to Highly Pathogenic Avian Influenza Outbreaks in the United States, 2014–2017

BackgroundIn the USA, poultry outbreaks of highly pathogenic avian influenza viruses (AI) caused by H5 and H7 viruses have raised concern about the risk of infections in humans. Based on data from Asian lineage H5 and H7 AI, which sporadically transmit from poultry to humans, CDC currently recommends active daily monitoring of persons exposed to H5 and H7 AI viruses, including those who wear personal protective equipment (PPE).MethodsPersons exposed to HPAI-infected birds or contaminated environments in the USA were actively monitored during exposure and for 10 days post-exposure for illness, during 2014–2017. Some exposed persons were monitored on-site by USDA or contract safety officers, company staff, or state health officials. State health department staff monitored people during the 10-day post-exposure period. Persons reporting any respiratory illness or conjunctivitis were swabbed for molecular influenza testing. Preliminary results are presented.ResultsFrom 2014 to 2017, 270 detections in poultry/wild birds were reported and at least 606 persons were potentially exposed to AI virus by exposure to birds, carcasses, or environment. Most exposed persons wore PPE. No human infections with AI viruses were detected.ConclusionThe risk of transmission of these H5 and H7 AI viruses to humans was low. These preliminary data offer evidence to change the recommendations for monitoring in persons exposed to these viruses. If final data support these findings, self-monitoring by workers with reporting to health departments if symptoms develop, rather than active monitoring by public health personnel, could be considered. However, it will be important to reconsider and update recommendations as the viruses evolve. Furthermore, risk of infection likely varies by exposure and those without PPE should be actively monitored.YearHPAI virusNo. of detections reportedEstimated no. birds destroyedNo. of persons exposedNo. HPAI positive/no. of ill and testedPercent ill of all exposed (95% exact binomial confidence interval)December 2014–June 2015H5N2 H5N8 H5N1 H5241 22 215,639,861 254,669 0103 56 3 2 1640/50 (0–0.02)2016H7N8 H5N21 1 42,600 0319 Missing0/20 Missing0 (0–0.01)2017H7N9 H5N22 1 127,956 0123 Missing0/1 Missing0 (0–0.03)Disclosures All authors: No reported disclosures.

Temporal and spatial characteristics of highly pathogenic avian influenza outbreaks in China during 2004 to 2015

Identifying the temporal and spatial characteristics of highly pathogenic avian influenza (HPAI) outbreaks is very important for developing effective and appropriate countermeasures against HPAI and promoting sustainable development in the poultry industry. This study aimed to analyze four aspects of the temporal and spatial characteristics of HPAI outbreaks in China, including the frequency of HPAI outbreaks, numbers of dead animals (died or culled), types of HPAI viruses, and species of infected animals. Temporal characteristics showed that the frequency of HPAI outbreaks decreased and then increased, with some years deviating from the main trend in 2004 to 2010 and 2011 to 2015, while the largest number of dead animals due to HPAI outbreaks was in 2005. During 2004 to 2015, HPAI H5N1 was the major type of HPAI virus, and chickens had the greatest risk of being infected with HPAI, followed by ducks and geese. The HPAI outbreaks had obvious seasonal effects clustered in January to February, June, and November. Spatial characteristics revealed that outbreaks were more frequent in Xinjiang, Hubei, and Guangdong but caused a larger number of dead animals in Liaoning and Shanxi. HPAI H5N1 appeared in 25 provinces, while HPAI H5N2 was mainly localized in Hebei and Jiangsu, and HPAI H5N6 occurred in Heilongjiang, Jiangsu, Hunan, and Guangdong. HPAI viruses were most frequently detected in chickens and wild birds in northern China, while the majority of HPAI infections were identified in chickens, ducks, and geese in southern China. Regionally, HPAI outbreaks were most frequent in the western region but resulted in larger number of animals dying or being culled in the eastern region. These findings could provide a new understanding of the distributional characteristics of HPAI outbreaks and offer prospects for better prevention and control strategies.

Movement and contact patterns of long-distance free-grazing ducks and avian influenza persistence in Vietnam.

Presence of ducks, and in particular of free-grazing ducks, has consistently been shown to be one of the most important risk factors for highly pathogenic avian influenza outbreaks which has compromised poultry production in South-East Asia since the early 2000s and continues to threaten public health, farmers’ livelihood and food security. Although free-grazing duck production has been practised for decades in South-East Asia, there are few published studies describing this production system, which is suspected to play an important role in the maintenance of avian influenza viruses. This study aimed at describing quantitatively the long-distance free-grazing duck production system in South Vietnam, characterising the movement and contact patterns of the duck flocks, and identifying potential associations between farming practices, movement and contact patterns and the circulation of avian influenza viruses. We conducted interviews among stakeholders involved in the free-grazing duck production system (duck farmers, transporters and rice paddy owners) in combination with a virological cross-sectional survey in South Vietnam. Results show that both direct and indirect contacts between free-grazing duck flocks were frequent and diverse. The flocks were transported extensively across district and province boundaries, mainly by boat but also by truck or on foot. A third of the investigated flocks had a positive influenza A virology test, indicating current circulation of avian influenza viruses, but none were positive for H5 subtypes. The age and size of the flock as well as its location at the time of sampling were associated with the risk of influenza A circulation in the flocks. These findings should be considered when developing risk assessment models of influenza virus spread aimed at informing the development of improved biosecurity practices leading to enhanced animal health, sustainable animal production and reliable income for farmers.

A GIS-Based Mapping to Identify Locations at Risk for Highly Pathogenic Avian Influenza Virus Outbreak in Korea

A GIS-Based Mapping to Identify Locations at Risk for Highly Pathogenic Avian Influenza Virus Outbreak in Korea

Evaluation of the presence of avian influenza receptors in oviducts of forced moulting birds using immunofluorescence

During the 2012 highly pathogenic avian influenza outbreak in Mexico caused by the H7N3 subtype, infection led to the death of approximately 22 million laying hens. Thus, poultry farmers were faced with a challenge to ensure the continued commercial flow of eggs. In addition to implementing established sanitary protocols and vaccination programs, forced moulting management was utilized in the affected areas. This strategy guaranteed the maintenance of egg production in the quarantined areas by decreasing the mortality of the infected flock while re-stimulating egg production. To understand how forced moulting reduced mortality of the infected birds, we examined the distribution of the avian influenza receptor in the oviduct of hens subjected to forced moulting. We tested if changes in the reproductive tract caused by forced moulting generated a decrease in the expression of the specific virus receptor in the cell membranes. Host susceptibility to the influenza virus was determined by the presence of these specific receptors. We utilized immunofluorescence of the Maackia amurensis lectin to identify the presence of the virus receptor in histological sections of the oviducts of birds in egg production and birds undergoing forced moulting. The results showed the presence and distribution of the receptors for avian influenza. A strong signal of the receptor was observed in the histological sections of the oviducts of birds in egg production. Conversely, the signal was low in the oviducts of birds undergoing forced moulting. These results demonstrate a decrease in the number of receptors of birds subjected to forced moulting. A lack of receptors would affect virus infection and replication as well as virus-induced damage in the oviduct, which may help explain the observation in the field that birds infected with avian influenza and subjected to forced moulting have decreased mortality.A. Abundant amount of influenza-like receptors, labelled with apple-green fluorescence, on the apical region of the ciliated cylindrical pseudostratifiedepithelium of the uterine region of healthy hens in production. Bar: 100 μm.

Thermo-tolerance and heat shock protein of Escherichia coli ATCC 25922 under thermal stress using test cell method

Pathogenic outbreaks related to consumption of dry foods have encouraged scientific communities to study the thermal resistance of the surrogate for thermal pasteurization validation tests. The purpose of this study was to investigate thermo-tolerance relative to mRNA levels in E. coli ATCC 25922 in LB broth at three temperatures after previous heat shock, and analyze heat shock protein levels after preconditioning by using aluminum test cell. The results showed that D-values for E. coli decreased as the temperature increased from 57 to 63 °C. The enhanced thermo-tolerance was found when the culture was subjected to three sub-lethal temperatures and reached maximum level at 45 °C for 5 min. The trend of relative mRNA level and the enhanced HSP 70 protein further confirmed the increased D-values after heat shock treatments. After storage at cold or room temperatures for a day, however, the enhanced thermo-tolerance of E. coli ATCC 25922 could be eliminated. Necessitate longer times at a lethal temperature are needed to guarantee the required food safety in developing effective pasteurization processes.

Antibody responses to avian influenza viruses in wild birds broaden with age.

For viruses such as avian influenza, immunity within a host population can drive the emergence of new strains by selecting for viruses with novel antigens that avoid immune recognition. The accumulation of acquired immunity with age is hypothesized to affect how influenza viruses emerge and spread in species of different lifespans. Despite its importance for understanding the behaviour of avian influenza viruses, little is known about age-related accumulation of immunity in the virus's primary reservoir, wild birds. To address this, we studied the age structure of immune responses to avian influenza virus in a wild swan population (Cygnus olor), before and after the population experienced an outbreak of highly pathogenic H5N1 avian influenza in 2008. We performed haemagglutination inhibition assays on sampled sera for five avian influenza strains and show that breadth of response accumulates with age. The observed age-related distribution of antibody responses to avian influenza strains may explain the age-dependent mortality observed during the highly pathogenic H5N1 outbreak. Age structures and species lifespan are probably important determinants of viral epidemiology and virulence in birds.

Lujo viral hemorrhagic fever: considering diagnostic capacity and preparedness in the wake of recent Ebola and Zika virus outbreaks.

SummaryLujo virus is a novel Old World arenavirus identified in Southern Africa in 2008 as the cause of a viral hemorrhagic fever (VHF) characterized by nosocomial transmission with a high case fatality rate of 80% (4/5 cases). Whereas this outbreak was limited, the unprecedented Ebola virus disease outbreak in West Africa, and recent Zika virus disease epidemic in the Americas, has brought into acute focus the need for preparedness to respond to rare but potentially highly pathogenic outbreaks of zoonotic or arthropod‐borne viral infections. A key determinant for effective control of a VHF outbreak is the time between primary infection and diagnosis of the index case. Here, we review the Lujo VHF outbreak of 2008 and discuss how preparatory measures with respect to developing diagnostic capacity might be effectively embedded into existing national disease control networks, such as those for human immunodeficiency virus, tuberculosis, and malaria.

Epizootics in Industrial Livestock Production: Preventable Gaps in Biosecurity and Biocontainment

While technological advances in animal husbandry have facilitated increases in global meat production, the high density and geographic concentration of food animal production facilities pose risks of infectious disease transmission. The scale of the 2014-2015 highly pathogenic avian influenza H5N2 outbreak in the United States demonstrates the challenges in achieving pathogen control within and around industrial animal facilities using existing technologies. We discuss gaps in current practice in two specific systems within these facilities - ventilation and waste management - which are under-recognized as important drivers of microbial porosity. The development of innovative ventilation systems to reduce influx and efflux of pathogens is critically needed, and cross-sectoral partnerships should be incentivized to do so. Adapting current human biosolid treatment technologies for farm applications, reducing animal stocking density and shifting waste management responsibility from farmer to corporation would reduce risk from current manure management systems. While innovative approaches to functionally altering the industrial food animal production system remain important priorities to promote sustainability, our intention here is to identify gaps within the current system that allow for pathogen emergence and transmission and address specific areas in which technological, administrative or policy changes are necessary to mitigate these risks.

Time-space analysis of highly pathogenic avian influenza H5N2 outbreak in the US.

BackgroundIn early 2015, highly pathogenic avian influenza H5N2 caused outbreaks in commercial poultry farms in Minnesota and neighboring states where more than 48 million birds were affected. To date, the origin and transmission pathways of HPAI H5N2 have not been conclusively established.MethodsIn this study, we analyzed forty-six samples from turkeys and their environment that were collected at different time-points of the outbreak to identify origins and within outbreak evolutionary changes. We performed de-novo whole genome sequencing from primary samples and the most recent common ancestors of the PB2, PA, HA5, M and NS segments were traced back to Japanese HPAI H5N8 isolates. These segments appeared to have diverged from the ancestor around June and November 2014.ResultsThe time to most recent common ancestor analysis for PB1, NP and NA2 segments suggest two likely possibilities of reassortant HPAI H5N2 origin - either a reassortment in Alaska area or multiple reassortments with North American low pathogenic avian influenza strains, before the HPAI H5N2 outbreak strain emerged. Within the outbreak, viruses clustered into two and three subgroups suggesting high substitution rates of 0.702x10-2 - 1.665x10-2 (subs/site/year), over the 5-month outbreak period.ConclusionsData are suggestive of a fast evolving HPAI strain within an outbreak that should be taken into consideration in developing appropriate control strategies in the future.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-016-0605-4) contains supplementary material, which is available to authorized users.

Epidemiological and Evolutionary Inference of the Transmission Network of the 2014 Highly Pathogenic Avian Influenza H5N2 Outbreak in British Columbia, Canada.

The first North American outbreak of highly pathogenic avian influenza (HPAI) involving a virus of Eurasian A/goose/Guangdong/1/1996 (H5N1) lineage began in the Fraser Valley of British Columbia, Canada in late November 2014. A total of 11 commercial and 1 non-commercial (backyard) operations were infected before the outbreak was terminated. Control measures included movement restrictions that were placed on a total of 404 individual premises, 150 of which were located within a 3 km radius of an infected premise(s) (IP). A complete epidemiological investigation revealed that the source of this HPAI H5N2 virus for 4 of the commercial IPs and the single non-commercial IP likely involved indirect contact with wild birds. Three IPs were associated with the movement of birds or service providers and localized/environmental spread was suspected as the source of infection for the remaining 4 IPs. Viral phylogenies, as determined by Bayesian Inference and Maximum Likelihood methods, were used to validate the epidemiologically inferred transmission network. The phylogenetic clustering of concatenated viral genomes and the median-joining phylogenetic network of the viruses supported, for the most part, the transmission network that was inferred by the epidemiologic analysis.

Case Series of Turkey Farms from the H5N2 Highly Pathogenic Avian Influenza Outbreak in the United States During 2015.

Between December 2014 and June 2015, an outbreak of H5N2 HPAI caused the largest and most expensive agriculture emergency in U.S. Department of Agriculture-Animal and Plant Health Inspection Service history. The outbreak affected 21 states; 232 poultry farms (211 commercial and 21 backyard) were affected, and approximately 49.6 million birds were depopulated on poultry farms. The majority of affected farms were commercial turkey operations (n = 160). This report is a case series describing 104 H5N2 HPAI-affected turkey farms in Iowa, Minnesota, Missouri, North Dakota, South Dakota, and Wisconsin that had H5N2 HPAI virus detected between March 5 and June 1, 2015. The farm manager or farm personnel voluntarily completed an epidemiologic questionnaire administered by state and federal animal health officials. Equipment and vehicle sharing with other farms was common, particularly for feed trucks (77% of farms shared feed trucks with other farms), live haul loaders (90.4%), poult trailers (72.0%), and preloaders (80.7%). Many farms had water bodies in proximity to the farm, such as a pond (42.6%) or stream (21.8%). About one-third of farms (33.7%) reported seeing wild birds inside the turkey barns. Only 44.2% of farms reported that third-party biosecurity audits or assessments had been conducted. Because the newly introduced Asian H5N8 HPAI and two new HPAI viruses, H5N2 and H5N1, are now circulating in U.S. wild birds, primarily migratory waterfowl, a greater potential for reoccurrence exists with the spring and fall migratory seasons, representing higher risk periods for outbreaks of HPAI in commercial poultry farms in the future. Eliminating exposure to wild birds, especially waterfowl or environments contaminated by wild waterfowl, will reduce risk of reintroduction of H5N2 HPAI virus, and ensuring good on-farm biosecurity will help the poultry industry avoid introduction of influenza and lateral spread between farms.

In silico evaluation of an aviar influenza AH5N1 virus outbreak with human to human transmission: effects of sanitary measures in Valencia, Venezuela, 2012

There is a risk for an avian influenza AH5N1 virus pandemia. To estimate the magnitude and impact of an AH5N1 pandemic in areas of Latin-America in order to design interventions and to reduce morbidity-mortality. The InfluSim program was used to simulate a highly pathogenic AH5N1 aviar virus epidemic outbreak with human to human transmission in Valencia, Venezuela. We estimated the day of maximal number of cases, number of moderately and severely ill patients, exposed individuals, deaths and associated costs for 5 different interventions: absence of any intervention; implementation of antiviral treatment; reduction of 20% in population general contacts; closure of 20% of educational institutions; and reduction of 50% in massive public gatherings. Simulation parameters used were: population: 829.856 persons, infection risk 6-47%, contagiousness Index Rh o 2,5; relative contagiousness 90%, overall lethality 64,1% and, costs according to the official basic budget. For an outbreak lasting 200 days direct and indirect deaths by intervention strategies would be: 29,907; 29,900; 9,701; 29,295 and 14,752. Costs would follow a similar trend. Reduction of 20% in general population contacts results in a significant reduction of up to 68% of cases. The outbreak would collapse the health care system. Antiviral treatment would not be efficient during the outbreak. Interpersonal contact reduction proved to be the best sanitary measure to control an AH5N1 theoretical epidemic outbreak.

A Novel High-Throughput Method for Molecular Detection of Human Pathogenic Viruses Using a Nanofluidic Real-Time PCR System.

Human enteric viruses are recognized as the main causes of food- and waterborne diseases worldwide. Sensitive and quantitative detection of human enteric viruses is typically achieved through quantitative RT-PCR (RT-qPCR). A nanofluidic real-time PCR system was used to develop novel high-throughput methods for qualitative molecular detection (RT-qPCR array) and quantification of human pathogenic viruses by digital RT-PCR (RT-dPCR). The performance of high-throughput PCR methods was investigated for detecting 19 human pathogenic viruses and two main process controls used in food virology. The conventional real-time PCR system was compared to the RT-dPCR and RT-qPCR array. Based on the number of genome copies calculated by spectrophotometry, sensitivity was found to be slightly better with RT-qPCR than with RT-dPCR for 14 viruses by a factor range of from 0.3 to 1.6 log10. Conversely, sensitivity was better with RT-dPCR than with RT-qPCR for seven viruses by a factor range of from 0.10 to 1.40 log10. Interestingly, the number of genome copies determined by RT-dPCR was always from 1 to 2 log10 lower than the expected copy number calculated by RT-qPCR standard curve. The sensitivity of the RT-qPCR and RT-qPCR array assays was found to be similar for two viruses, and better with RT-qPCR than with RT-qPCR array for eighteen viruses by a factor range of from 0.7 to 3.0 log10. Conversely, sensitivity was only 0.30 log10 better with the RT-qPCR array than with conventional RT-qPCR assays for norovirus GIV detection. Finally, the RT-qPCR array and RT-dPCR assays were successfully used together to screen clinical samples and quantify pathogenic viruses. Additionally, this method made it possible to identify co-infection in clinical samples. In conclusion, given the rapidity and potential for large numbers of viral targets, this nanofluidic RT-qPCR assay should have a major impact on human pathogenic virus surveillance and outbreak investigations and is likely to be of benefit to public health.

Containing an Outbreak of Human Pathogenic Avian Influenza Outbreak in Nadia district of West Bengal-India

Background: On 12th September 2011, unusual poultry deaths were reported from a poultry farm at Putimari Christianpara under Tehatta Gram Panchayat. On 14th September there were more deaths accordingly, samples were collected and sent to the Regional Disease Diagnostic Laboratory, Kolkata. Preliminary reports confirmed the presence of avian influenza. High Security Disease Detection Laboratory at Bhopal confirmed avian influenza. The state Govt notified the outbreak as avian influenza on 19th September 2010. This outbreak was investigated and epidemiological characteristic & containment measures were described. Material and Methods: Operational definition of avian influenza was established. Fever surveillance in animals and human beings was conducted within 10 kms radius of epicenters. Culling was conducted. All health workers, and cullers were examined and prophylaxis was administered. Results: Out of total 56 Gram Panchayat 25(45%) were affected. Out of 568 villages 131(23%) were affected. Out of 131 affected villages 22 were in the core area and the rest outside. Population affected was estimated to be 400007. Mean population covered per day was 104603 (26%). Conclusion: In all 217 cases were detected with upper respiratory tract but none matched the case definition of avian influenza. Key words: Avian Influenza, H5N1, Surveillance, Culling, Nadia District, West Bengal

Characterization of H5N1 influenza A virus that caused the first highly pathogenic avian influenza outbreak in Saudi Arabia.

Saudi Arabia (SA) experienced a highly pathogenic avian influenza (HPAI) H5N1 outbreak in domesticated birds in 2007. Forty-three hemagglutinin (HA) and 41 neuraminidase (NA) genes of HPAI H5N1 viruses were sequenced and phylogenetic analyses of completely sequenced genes were performed to compare with other viral HA and NA gene sequences available in the public databases. Molecular characterization of the H5N1 viruses revealed two genetically distinct clades, 2.2.2 and 2.3.1, of H5N1 viruses circulating in the area. Amino acid sequence analysis of the HA gene indicated that the virus from 2.2.2 contained the sequence SPQGERRRK-R/G at the cleavage site, while the virus from 2.3.1 contained the sequence SPQRERRRK-R/G. Additionally, a few mutations with amino acid substitutions such as M226I at N-link glycosylation site were identified in two of these isolates. Amino acid sequence of the NA gene showed a 20-amino-acid deletion in the NA stalk region, required for enhanced virulence of influenza viruses and its adaptation from wild birds to domestic chickens. As close contact between humans and birds is unavoidable, there is a need for a thorough understanding of the virus epidemiology, factors affecting the spread of the virus, and molecular characterization such as phylogeny and substitution rates of H5N1 viruses circulating in the region. Two genetically distinct clades were found to be circulating in the country, which could likely result in recombination and emergence of more virulent viral strains. These findings could be helpful for the authorities devising control measures against these viruses.

The Development of Pathogenicity of Avian Influenza Virus Isolated from Indonesia

Highly pathogenic avian infl uenza outbreak in Indonesia has been reported in various poultry due toH5N1 subtype. The presence of multiple basic amino acids within the cleavage site of HA glycoprotein hasbeen identifi ed to be associated with the pathogenicity of avian infl uenza virus. The study was retrospectivestudy which was designed to characterize the cleavage site and fusion site region of haemagglutinin gene ofAIV isolated from various poultry in 2003 to 2013. Isolation, Identifi cation and propagation were carried outto collect viral stock. For virus detection, reverse transcriptase PCR (RT-PCR) method on H5 and N1 genefragment was performed. All of RT-PCR HA gene positive products were sequenced for further nucleotideanalysis and to determine the nucleotide composition at the targeted fragment. The results are all AIV isolateswere identifi ed as H5N1 subtype. The sequence analyses revealed some motives of basic amino acid motivethat were classifi ed as highly pathogenic avian infl uenza virus. Further analyses on fusion domain of all AIVisolated during the period 2003 to 2013 showed conserved amino acid. Keywords: avian infl uenza, haemagglutinin, cleavage site, basic amino acid, fusion site

Avian influenza in Australia: a summary of 5 years of wild bird surveillance.

Avian influenza viruses (AIVs) are found worldwide in numerous bird species, causing significant disease in gallinaceous poultry and occasionally other species. Surveillance of wild bird reservoirs provides an opportunity to add to the understanding of the epidemiology of AIVs. This study examined key findings from the National Avian Influenza Wild Bird Surveillance Program over a 5-year period (July 2007-June 2012), the main source of information on AIVs circulating in Australia. The overall proportion of birds that tested positive for influenza A via PCR was 1.9 ± 0.1%, with evidence of widespread exposure of Australian wild birds to most low pathogenic avian influenza (LPAI) subtypes (H1-13, H16). LPAI H5 subtypes were found to be dominant and widespread during this 5-year period. Given Australia's isolation, both geographically and ecologically, it is important for Australia not to assume that the epidemiology of AIV from other geographic regions applies here. Despite all previous highly pathogenic avian influenza outbreaks in Australian poultry being attributed to H7 subtypes, widespread detection of H5 subtypes in wild birds may represent an ongoing risk to the Australian poultry industry.

Quantitative Estimation of the Number of Contaminated Hatching Eggs Released from an Infected, Undetected Turkey Breeder Hen Flock During a Highly Pathogenic Avian Influenza Outbreak.

The regulatory response to an outbreak of highly pathogenic avian influenza (HPAI) in the United States may involve quarantine and stop movement orders that have the potential to disrupt continuity of operations in the U.S. turkey industry--particularly in the event that an uninfected breeder flock is located within an HPAI Control Area. A group of government-academic-industry leaders developed an approach to minimize the unintended consequences associated with outbreak response, which incorporates HPAI control measures to be implemented prior to moving hatching eggs off of the farm. Quantitative simulation models were used to evaluate the movement of potentially contaminated hatching eggs from a breeder henhouse located in an HPAI Control Area, given that active surveillance testing, elevated biosecurity, and a 2-day on-farm holding period were employed. The risk analysis included scenarios of HPAI viruses differing in characteristics as well as scenarios in which infection resulted from artificial insemination. The mean model-predicted number of internally contaminated hatching eggs released per movement from an HPAI-infected turkey breeder henhouse ranged from 0 to 0.008 under the four scenarios evaluated. The results indicate a 95% chance of no internally contaminated eggs being present per movement from an infected house before detection. Sensitivity analysis indicates that these results are robust to variation in key transmission model parameters within the range of their estimates from available literature. Infectious birds at the time of egg collection are a potential pathway of external contamination for eggs stored and then moved off of the farm; the predicted number of such infectious birds was estimated to be low. To date, there has been no evidence of vertical transmission of HPAI virus or low pathogenic avian influenza virus to day-old poults from hatching eggs originating from infected breeders. The application of risk analysis methods was beneficial for evaluating outbreak measures developed through emergency response planning initiatives that consider the managed movement of hatching eggs from monitored premises in an HPAI Control Area.