Risk of influenza A (H5N1) infection among poultry workers, Hong Kong, 1997-1998

The Biosafety Research Road Map: The Search for Evidence to Support Practices in the Laboratory-Zoonotic Avian Influenza and Mycobacterium tuberculosis

Introduction

The Biosafety Research Road Map reviewed the scientific literature on a viral respiratory pathogen, avian influenza virus, and a bacterial respiratory pathogen, Mycobacterium tuberculosis. This project aims at identifying gaps in the data required to conduct evidence-based biorisk assessments, as described in Blacksell et al. One significant gap is the need for definitive data on M. tuberculosis sample aerosolization to guide the selection of engineering controls for diagnostic procedures.

Methods

The literature search focused on five areas: routes of inoculation/modes of transmission, infectious dose, laboratory-acquired infections, containment releases, and disinfection and decontamination methods.

Results

The available data regarding biosafety knowledge gaps and existing evidence have been collated and presented in Tables 1 and 2. The guidance sources on the appropriate use of biosafety cabinets for specific procedures with M. tuberculosis require clarification. Detecting vulnerabilities in the biorisk assessment for respiratory pathogens is essential to improve and develop laboratory biosafety in local and national systems.

An assessment of the highly pathogenic avian influenza resurgence at human-poultry-environment interface in North-central Nigeria: Sociocultural determinants and One Health implications

Highly pathogenic avian influenza H5N1 resurgence has occurred in Nigerian domestic bird flocks with public health concern. This study assessed poultry farmers' knowledge, perceptions, and biosecurity and biosafety practices regarding H5N1 resurgence, explore risk pathways for viral dissemination and associated socio-cultural and economic drivers in poultry flocks in Nigeria. A cross-sectional survey was carried out in randomly selected two poultry production systems, commercial intensive poultry production system and the backyard traditional free-range poultry production system. A One Health framework model was conceptualized to assess inter-links of biophysical, environmental, and sociocultural activities that interface to drive resurgence for better interventions. Descriptive and analytical statistical analyses were performed at 95% confidence level. Of the 422 recruited poultry farmers, 98.6% (n = 416) participated. Majorities of smallholder commercial farmers (93.5%) and backyard poultry keepers (97.7%) engaged in intensive and extensive management, respectively. Identified significant zoonotic risk pathways for H5N1 virus spread were through consumption of undercooked poultry meat and products, and contacts with infected birds and contaminated fomites. Separation of sick birds from apparently healthy ones, frequent cleaning and disinfection of equipment and premises, movement control of birds to nearby water bodies, use of personal protective equipment, and movement control of persons and vehicles into the flock settlements were significantly practiced biosecurity measures. Presence of nearby water bodies (ponds) close to flock settlements (p < 0.001), frequent contact of wild and domestic birds (p < 0.001), cultural practice of bird exchange between flocks (p < 0.001), and wild waterfowls' seasonal migrations (p < 0.001) significantly influenced resurgence. Understanding determinants interactions in the 'Conceptual One Health framework model' is required for better intercontinental intervention against HPAI H5N1. Reform of socio-cultural and economic activities using One Health approach will not only assure food safety and food security, but also guarantee public and environmental health.

A cross-sectional survey of avian influenza knowledge among poultry farmworkers in Indonesia

Background

Avian influenza (AI) poses a serious threat to global public health, especially the highly pathogenic form. Awareness and protective behavior among the public, particularly the high-risk populations, are essential for prevention and control. This study aimed to ascertain the level of AI knowledge among Indonesia's poultry farmworkers.

Methods

This was a cross-sectional study conducted online. A predesigned standardized questionnaire, containing six demographic questions and 14 questions on AI knowledge, was used. The questionnaire was distributed via WhatsApp and email platforms. Volunteers (respondents) included 119 men and 81 women, aged 18-50 years, who work on poultry farms in Indonesia. Data were analyzed using the chi-squared and Fisher exact tests.

Results

The study's findings revealed that more than two-thirds (67.0%) of the respondents had heard about AI. Their primary sources of information were health workers (36.0%) and media, especially television (34.0%). The majority of the participants (91.3%) had good knowledge about AI as a contagious infection, transmissible from birds to other birds, animals, or humans. A total of 76.8% of the respondents believed that poultry workers and veterinarians were at high risk of contracting AI infection.

Conclusions

The study concluded that poultry workers had good knowledge about AI infection, transmission, and risk variables. Health workers and television were the main sources of information on AI. The level of AI knowledge was high among the respondents.

Avian influenza (H5N1) virus, epidemiology and its effects on backyard poultry in Indonesia: a review

Avian influenza (AI) is a zoonotic viral endemic disease that affects poultry, swine, and mammals, including humans. Highly pathogenic avian influenza (HPAI) is caused by influenza type A virus subtypes H5, and H7 which are naturally carried by a wild bird and often affect domestic poultry. Avian influenza (AI) is a major problem worldwide that causes significant economic losses in the poultry sector. Since 2003, the widespread H5N1 HPAI in poultry has led to high mortalities resulting in huge economic losses in the poultry sector in Indonesia. Domestic poultry is a key source of income that contributes to economic growth, both directly and indirectly, by reducing poverty among the people living in rural communities. Furthermore, in many developing countries, including Indonesia, rural people meet a portion of their food needs through backyard poultry. Nevertheless, this sector is strongly affected by biosecurity hazards, particularly in Indonesia by HPAI infections. Avian influenza (AI), subtype H5N1 has zoonotic significance, posing major risks to public health and poultry. Due to close interaction between wild migratory birds and ducks, the domestic poultry sector in Indonesia is directly affected by this virus. This virus continues to be ubiquitous in Indonesia as a result of the unpredictable mutations produced by antigenic drift and shift, which can persist from a few days to several years. In this review, the epidemiology and impact, of highly pathogenic avian influenza H5N1 subtype virus infection on backyard poultry in Indonesia were discussed.

Avian influenza (H5N1) virus, epidemiology and its effects on backyard poultry in Indonesia: a review

Avian influenza (AI) is a zoonotic viral endemic disease that affects poultry, swine, and mammals, including humans. Highly pathogenic avian influenza (HPAI) is caused by influenza type A virus subtypes H5, and H7 which are naturally carried by a wild bird and often affect domestic poultry. Avian influenza (AI) is a major problem worldwide that causes significant economic losses in the poultry sector. Since 2003, the widespread H5N1 HPAI in poultry has led to high mortalities resulting in huge economic losses in the poultry sector in Indonesia. Domestic poultry is a key source of income that contributes to economic growth, both directly and indirectly, by reducing poverty among the people living in rural communities. Furthermore, in many developing countries, including Indonesia, rural people meet a portion of their food needs through backyard poultry. Nevertheless, this sector is strongly affected by biosecurity hazards, particularly in Indonesia by HPAI infections. Avian influenza (AI), subtype H5N1 has zoonotic significance, posing major risks to public health and poultry. Due to close interaction between wild migratory birds and ducks, the domestic poultry sector in Indonesia is directly affected by this virus. This virus continues to be ubiquitous in Indonesia as a result of the unpredictable mutations produced by antigenic drift and shift, which can persist from a few days to several years. In this review, the epidemiology and impact, of highly pathogenic avian influenza H5N1 subtype virus infection on backyard poultry in Indonesia were discussed.

Comparison of samplers collecting airborne influenza viruses: 1. Primarily impingers and cyclones

Researchers must be able to measure concentrations, sizes, and infectivity of virus-containing particles in animal agriculture facilities to know how far infectious virus-containing particles may travel through air, where they may deposit in the human or animal respiratory tract, and the most effective ways to limit exposures to them. The objective of this study was to evaluate a variety of impinger and cyclone aerosol or bioaerosol samplers to determine approaches most suitable for detecting and measuring concentrations of virus-containing particles in air. Six impinger/cyclone air samplers, a filter-based sampler, and a cascade impactor were used in separate tests to collect artificially generated aerosols of MS2 bacteriophage and swine and avian influenza viruses. Quantification of infectious MS2 coliphage was carried out using a double agar layer procedure. The influenza viruses were titrated in cell cultures to determine quantities of infectious virus. Viral RNA was extracted and used for quantitative real time RT-PCR, to provide total virus concentrations for all three viruses. The amounts of virus recovered and the measured airborne virus concentrations were calculated and compared among the samplers. Not surprisingly, high flow rate samplers generally collected greater quantities of virus than low flow samplers. However, low flow rate samplers generally measured higher, and likely more accurate, airborne concentrations of Infectious virus and viral RNA than high flow samplers. To assess airborne viruses in the field, a two-sampler approach may work well. A suitable high flow sampler may provide low limits of detection to determine if any virus is present in the air. If virus is detected, a suitable lower flow sampler may measure airborne virus concentrations accurately.

Lessons From Influenza Pandemics of the Last 100 Years

Seasonal influenza is an annual occurrence, but it is the threat of pandemics that produces universal concern. Recurring reports of avian influenza viruses severely affecting humans have served as constant reminders of the potential for another pandemic. Review of features of the 1918 influenza pandemic and subsequent ones helps in identifying areas where attention in planning is critical. Key among such issues are likely risk groups and which interventions to employ. Past pandemics have repeatedly underscored, for example, the vulnerability of groups such as pregnant women and taught other lessons valuable for future preparedness. While a fundamental difficulty in planning for the next pandemic remains their unpredictability and infrequency, this uncertainty can be mitigated, in part, by optimizing the handling of the much more predictable occurrence of seasonal influenza. Improvements in antivirals and novel vaccine formulations are critical in lessening the impact of both pandemic and seasonal influenza.

Serological evidence of human infections with highly pathogenic avian influenza A(H5N1) virus: a systematic review and meta-analysis

BACKGROUND

Highly pathogenic avian influenza A(H5N1) virus poses a global public health threat given severe and fatal zoonotic infections since 1997 and ongoing A(H5N1) virus circulation among poultry in several countries. A comprehensive assessment of the seroprevalence of A(H5N1) virus antibodies remains a gap and limits understanding of the true risk of A(H5N1) virus infection.

METHODS

We conducted a systematic review and meta-analysis of published serosurveys to assess the risk of subclinical and clinically mild A(H5N1) virus infections. We assessed A(H5N1) virus antibody titers and changes in titers among populations with variable exposures to different A(H5N1) viruses.

RESULTS

Across studies using the World Health Organization-recommended seropositive definition, the point estimates of the seroprevalence of A(H5N1) virus-specific antibodies were higher in poultry-exposed populations (range 0-0.6%) and persons exposed to both human A(H5N1) cases and infected birds (range 0.4-1.8%) than in close contacts of A(H5N1) cases or the general population (none to very low frequencies). Seroprevalence was higher in persons exposed to A(H5N1) clade 0 virus (1.9%, range 0.7-3.2%) than in participants exposed to other clades of A(H5N1) virus (range 0-0.5%) (p < 0.05). Seroprevalence was higher in poultry-exposed populations (range 0-1.9%) if such studies utilized antigenically similar A(H5N1) virus antigens in assays to A(H5N1) viruses circulating among poultry.

CONCLUSIONS

These low seroprevalences suggest that subclinical and clinically mild human A(H5N1) virus infections are uncommon. Standardized serological survey and laboratory methods are needed to fully understand the extent and risk of human A(H5N1) virus infections.

Seroprevalence of highly pathogenic avian influenza (H5N1) virus infection among humans in mainland China: A systematic review and meta-analysis

Although the effective transmission of the H5N1 virus from humans to humans has yet to be further observed, humans are at increased risk of a pandemic caused by H5N1. In order to fully evaluate the seroprevalence and risk factor of highly pathogenic avian influenza A (H5N1) virus infection among in mainland China, we performed a systematic review and meta-analysis. In this review, we searched literature on the seroprevalence of H5N1 infection among humans in mainland China from 1 January 1997 to 20 October 2018 in English and Chinese databases, including PubMed, Google scholar, Cochrane library, Clinical Trial, VIP, CNKI and WanFang database. We made a selection according to the title and the abstract of paper, and then, we excluded duplicated literature, and data incomplete literature according to the exclusion criteria we formulated. Finally, we extracted how many humans have H5N1 infection from the obtained studies to establish the seroprevalence of H5N1 infection among humans in mainland China. A total of 56 studies (including data of 35,159 humans) were compliant with our criteria. In China, the overall seroprevalence of H5N1 infection among humans was 2.45% (862/35,159), while the seroprevalence of H5N1 infection among humans from central China was 7.32% (213/2,911), higher than those in other regions of China. The seroprevalence of H5N1 infection was associated with test method, sampling time and demographic characteristics of humans. However, there was no significant difference in the effect of gender on the seroprevalence of H5N1 among humans in China. The purpose of this review was to better understand the real infection rate of H5N1 virus among humans and evaluate the potential risk factors for the zoonotic spread of H5N1 virus to humans. Sufficient epidemiological data are important to explore and understand the prevalent status of AIVs throughout the country and to disease control.

Pig Exposure and Health Outcomes in Hospitalized Infectious Disease Patients in Vietnam

Many infectious diseases have a zoonotic origin, and several have had major public health implications. Contact with animals is a known risk factor for zoonotic infections, although there are limited data on disease symptoms and pathogens associated with contact with different animal species. The rise in pig production in Southeast Asia has contributed to the emergence and re-emergence of zoonotic infections caused by contact with pigs and pig products. To compare the symptom and pathogen profiles of hospitalized patients with and without pig contact, we collected data on disease symptoms, infecting pathogens, and animal contact behaviour from patients attending six hospitals across Vietnam between 2012 and 2016. Patients who had previous contact with pigs were more likely to have enteric disease than respiratory or central nervous system infections and were more likely to grow Escherichia coli and Shigella from stool culture than those without pig contact. Patients with enteric infections who kept pigs were also more likely to have a disease of unknown origin. Public health initiatives that account for differences in animal contact behaviours and offer more comprehensive diagnostics in high-risk individuals are needed if emergence and re-emergence of zoonotic disease is to be monitored and prevented.

Highly Pathogenic Avian Influenza A(H5N1) Outbreaks in West Java Indonesia 2015-2016: Clinical Manifestation and Associated Risk Factors

Knowledge of outbreaks and associated risk factors is helpful to improve control of the Highly Pathogenic Avian Influenza A(H5N1) virus (HPAI) in Indonesia. This study was conducted to detect outbreaks of HPAI H5N1 in endemically infected regions by enhanced passive surveillance, to describe the clinical manifestation of these outbreaks and identify associated risk factors. From November 2015 to November 2016, HPAI outbreak investigations were conducted in seven districts of West Java. In total 64 outbreaks were confirmed out of 75 reported suspicions and outbreak characteristics were recorded. The highest mortality was reported in backyard chickens (average 59%, CI95%: 49-69%). Dermal apoptosis and lesions (64%, CI95%: 52-76%) and respiratory signs (39%, CI95%: 27-51%) were the clinical signs observed overall most frequently, while neurological signs were most frequently observed in ducks (68%, CI95%: 47-90%). In comparison with 60 non-infected control farms, the rate of visitor contacts onto a farm was associated with the odds of HPAI infection. Moreover, duck farms had higher odds of being infected than backyard farms, and larger farms had lower odds than small farms. Results indicate that better external biosecurity is needed to reduce transmission of HPAI A(H5N1) in Indonesia.

Poultry trading behaviours in Vietnamese live bird markets as risk factors for avian influenza infection in chickens

Vietnamese poultry are host to co‐circulating subtypes of avian influenza viruses, including H5N1 and H9N2, which pose a great risk to poultry productivity and to human health. AIVs circulate throughout the poultry trade network in Vietnam, with live bird markets being an integral component to this network. Traders at LBMs exhibit a variety of trading practices, which may influence the transmission of AIVs. We identified trading practices that impacted on AIV prevalence in chickens marketed in northern Vietnamese LBMs. We generated sequencing data for 31 H9N2 and two H5N6 viruses. Viruses isolated in the same LBM or from chickens sourced from the same province were genetically closer than viruses isolated in different LBMs or from chickens sourced in different provinces. The position of a vendor in the trading network impacted on their odds of having AIV‐infected chickens. Being a retailer and purchasing chickens from middlemen was associated with increased odds of infection, whereas odds decreased if vendors purchased chickens directly from large farms. Odds of infection were also higher for vendors having a greater volume of ducks unsold per day. These results indicate how the spread of AIVs is influenced by the structure of the live poultry trading network.

Different Pathogenicity and Transmissibility of Goose-Origin H5N6 Avian Influenza Viruses in Chickens

Highly pathogenic avian influenza H5N6 viruses have been circulating in poultry in Asia since 2013 and producing serious diseases in chickens. Here, we analyzed the genetic properties of 10 H5N6 subtypes AIVs from geese in 2015–2016 in Guangdong province. Phylogenic analysis showed that all HA genes of the 10 viruses belonged to clade 2.3.4.4, and their genes including HA, PA, PB1, M, NP, and NS all derived from Mix-like 1 (CH, VN, LS). Their PB2 genes come from Mix-like 2 (CH, VN, JP). The NA genes were classified into a Eurasian lineage. Therefore, the 10 viruses likely originate from the same ancestor and were all recombinant viruses between different genotypes. We selected A/Goose/Guangdong/GS144/2015(H5N6) (GS144) and A/Goose/Guangdong/GS148/2016(H5N6) (GS148) viruses to inoculate 5-week-old chickens intranasally with 10⁴ EID₅₀/0.1 mL dose intranasally to assess their pathogenicity and transmissibility. Inoculated chickens showed that the GS144 virus caused systematic infection with a lethality of 100%, but the lethality of GS148 virus was 0%. The two viruses were efficiently transmitted to contact chickens. The lethality of GS144 and GS148 virus in contact with chickens was 87.5% and 0%, respectively, which suggests that the transmissibility of GS144 virus was stronger than GS148 virus in chickens. Thus, different H5N6 viruses from the same waterfowl can show different pathogenicity and transmissibility in chickens. Continued surveillance and characteristic analysis of the H5N6 viruses will help us to keep abreast of evolution and variation in avian influenza viruses in the future.

Avian influenza in the Greater Mekong Subregion, 2003-2018

The persistent circulation of avian influenza viruses (AIVs) is an ongoing problem for many countries in South East Asia, causing large economic losses to both the agricultural and health sectors. This review analyses AIV diversity, evolution and the risk of AIV emergence in humans in countries of the Greater Mekong Subregion (GMS): Cambodia, Laos, Myanmar, Thailand and Vietnam (excluding China). The analysis was based on AIV sequencing data, serological studies, published journal articles and AIV outbreak reports available from January 2003 to December 2018. All countries of the GMS have suffered losses due repeated outbreaks of highly pathogenic (HP) H5N1 that has also caused human cases in all GMS countries. In Laos, Myanmar and Vietnam AIV outbreaks in domestic poultry have also been caused by clade 2.3.4.4 H5N6. A diverse range of low pathogenic AIVs (H1-H12) have been detected in poultry and wild bird species, though surveillance for and characterization of these subtypes is limited. Subtype H3, H4, H6 and H11 viruses have been detected over prolonged periods; whilst H1, H2, H7, H8, H10 and H12 viruses have only been detected transiently. H9 AIVs circulate endemically in Cambodia and Vietnam with seroprevalence data indicating human exposure to H9 AIVs in Cambodia, Thailand and Vietnam. As surveillance studies focus heavily on the detection of H5 AIVs in domestic poultry further research is needed to understand the true level of AIV diversity and the risk AIVs pose to humans in the GMS.

Serosurveillance of avian influenza A/H5N6 virus infection in poultry farmers, Gyeonggi Province, Republic of Korea, 2016-2017

OBJECTIVES

Between November 20, 2016 and April 17, 2017, outbreaks of highly pathogenic avian influenza (HPAI) A/H5N6 occurred on poultry farms in Gyeonggi Province in the Republic of Korea. A serosurvey was conducted among poultry farmers to identify the transmission of HPAI A/H5N6 virus to humans.

METHODS

A descriptive study of 870 poultry farmers in Gyeonggi Province in Korea was conducted during the 2016-2017 outbreaks. Serological testing was performed using a microneutralization (MN) assay for antibodies against influenza A/duck/ES2/Korea/2016 virus, which has antigenic properties similar to those of the HPAI A/H5N6 virus that caused this poultry outbreak.

RESULTS

Overall, 523 exposed poultry farmers were assessed by serological testing. Consequently, all tested negative for HPAI A/H5N6 virus via MN assay.

CONCLUSIONS

Based on serological assays, no transmission of HPAI A/H5N6 to humans was identified in this study cohort. Additional studies should be conducted to determine the possibility of poultry-to-human transmission of HPAI A/H5N6.

Adenovirus Type 21 Outbreak Among Lung Transplant Patients at a Large Tertiary Care Hospital

Here we summarize an April 2016, 7-patient cluster of human adenovirus (HAdV) infections in a cardiothoracic surgery intensive care unit. We show that the patients were infected with a single HAdV21b type. Rapid HAdV typing diagnostics and effective antiviral interventions are needed for immunocompromised patients suffering from HAdV infections.

Risk Factors for Avian Influenza H9 Infection of Chickens in Live Bird Retail Stalls of Lahore District, Pakistan 2009-2010

This study was conducted to identify risk factors associated with AIV infections in live bird retail stalls (LBRS) in Lahore District, Pakistan. A cross-sectional survey of LBRS was conducted from December 2009-February 2010 using two-stage cluster sampling based on probability proportional to size. A total of 280 oropharyngeal swab sample pools were collected from 1400 birds in 8 clusters and tested by qRT-PCR for the matrix (M) gene of type A influenza virus and HA gene subtypes H9, H5 and H7. Thirty-four (34) samples were positive for the M gene, of which 28 were also positive for H9. No sample was found positive for H5 or H7. Data for 36 potential risk factors, collected by questionnaire, were analyzed by survey-weighted logistic regression and prevalence odds ratios (OR) for associated risk factors were calculated. A final multivariable model identified three risk factors for H9 infection in LRBS, namely obtaining birds from mixed sources (OR 2.28, CI_95%: 1.4–3.7), keeping birds outside cages (OR 3.10, CI_95%: 1.4–7.0) and keeping chicken breeds other than broilers (OR 6.27, CI_95%: 1.7–23.2). Sourcing birds from dealers/wholesalers, keeping birds inside cages and avoiding mixing different breeds in cages could reduce the risk of H9 infections in LRBS.

Low risk of avian influenza A (H5N6) transmission to depopulation workers in Korea

An outbreak of highly pathogenic avian influenza A (H5N6) virus occurred between November 20, 2016, and March 1, 2017 in poultry farms, in the Gyeonggi Province, Republic of Korea. To identify the risk of transmission of H5N6 to depopulation workers, active and passive surveillance was conducted. Virological testing of respiratory swabs with real‐time reverse transcription‐polymerase chain reaction was performed for workers who reported respiratory symptoms. Among 4633 depopulation workers, 22 reported respiratory symptoms, but all tested negative for H5N6. Personal protective equipment in addition to antiviral prophylaxis was adequate to limit transmission of H5N6 from poultry to humans.

Evaluating interest in an influenza A(H5N1) vaccine among laboratory workers who work with highly-pathogenic avian influenza viruses in the United States

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Highly pathogenic avian influenza viruses pose an occupational risk to laboratorians.

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The majority of survey respondents were interested in the Q-Pan H5N1 vaccine.

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Interest in vaccination varied by role in the laboratory and time spent with HPAI viruses.

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Q-Pan H5N1 vaccine could be used in tandem with current biosafety practices for HPAI laboratorians.

Background

Highly pathogenic avian influenza A (HPAI) viruses found in poultry and wild birds occasionally infect humans and can cause serious disease. In 2014, the Advisory Committee on Immunization Practices (ACIP) reviewed data from one licensed ASO3-adjuvanted influenza A(H5N1) vaccine for consideration of use during inter-pandemic periods among persons with occupational exposure. To guide vaccine policy decisions, we conducted a survey of laboratory workers to assess demand for HPAI vaccination.

Methods

We designed an anonymous web survey (EpiInfo 7.0) to collect information on demographics, type of work and time spent with HPAI viruses, and interest in HPAI vaccination. Eligible participants were identified from 42 entities registered with United States Department of Agriculture’s Agricultural Select Agent program in 2016 and emailed electronic surveys. Personnel with Biosafety Level 3 enhanced (BSL-3E) laboratory access were surveyed. Descriptive analysis was performed.

Results

Overall, 131 responses were received from 33 principal investigators, 26 research scientists, 24 technicians, 15 postdoctoral fellows, 6 students, and 27 others. The estimated response rate was 15% among the laboratory personnel of responding principal investigators. One hundred respondents reported working in a BSL-3E area where HPAI experiments occurred with a mean time of 5.1–11.7 h per week. Overall, 49% were interested in receiving an A(H5N1) vaccine. By role, interest was highest among students (80%) and among those who spent >50% of their time in a BSL-3E area (64%). Most (61%) of those who said they might be or were not interested in vaccine believed it would not provide additional protection to current safety practices.

Conclusions

Half of responding laboratory workers was interested in receiving an influenza A(H5N1) vaccine. HPAI vaccination of laboratory workers at risk of occupational exposure could be used along with existing safety practices to protect this population.

Molecular Markers for Interspecies Transmission of Avian Influenza Viruses in Mammalian Hosts

In the last decade, a wide range of avian influenza viruses (AIVs) have infected various mammalian hosts and continuously threaten both human and animal health. It is a result of overcoming the inter-species barrier which is mostly associated with gene reassortment and accumulation of mutations in their gene segments. Several recent studies have shed insights into the phenotypic and genetic changes that are involved in the interspecies transmission of AIVs. These studies have a major focus on transmission from avian to mammalian species due to the high zoonotic potential of the viruses. As more mammalian species have been infected with these viruses, there is higher risk of genetic evolution of these viruses that may lead to the next human pandemic which represents and raises public health concern. Thus, understanding the mechanism of interspecies transmission and molecular determinants through which the emerging AIVs can acquire the ability to transmit to humans and other mammals is an important key in evaluating the potential risk caused by AIVs among humans. Here, we summarize previous and recent studies on molecular markers that are specifically involved in the transmission of avian-derived influenza viruses to various mammalian hosts including humans, pigs, horses, dogs, and marine mammals.

A Systematic Review and Meta-Analysis of Practices Exposing Humans to Avian Influenza Viruses, Their Prevalence, and Rationale

Almost all human infections by avian influenza viruses (AIVs) are transmitted from poultry. A systematic review was conducted to identify practices associated with human infections, their prevalence, and rationale. Observational studies were identified through database searches. Meta-analysis produced combined odds ratio estimates. The prevalence of practices and rationales for their adoptions were reported. Of the 48,217 records initially identified, 65 articles were included. Direct and indirect exposures to poultry were associated with infection for all investigated viral subtypes and settings. For the most frequently reported practices, association with infection seemed stronger in markets than households, for sick and dead than healthy poultry, and for H7N9 than H5N1. Practices were often described in general terms and their frequency and intensity of contact were not provided. The prevalence of practices was highly variable across studies, and no studies comprehensively explored reasons behind the adoption of practices. Combining epidemiological and targeted anthropological studies would increase the spectrum and detail of practices that could be investigated and should aim to provide insights into the rationale(s) for their existence. A better understanding of these rationales may help to design more realistic and acceptable preventive public health measures and messages.

Epidemiological Risk Factors for Animal Influenza A Viruses Overcoming Species Barriers

Drivers and risk factors for Influenza A virus transmission across species barriers are poorly understood, despite the ever present threat to human and animal health potentially on a pandemic scale. Here we review the published evidence for epidemiological risk factors associated with influenza viruses transmitting between animal species and from animals to humans. A total of 39 papers were found with evidence of epidemiological risk factors for influenza virus transmission from animals to humans; 18 of which had some statistical measure associated with the transmission of a virus. Circumstantial or observational evidence of risk factors for transmission between animal species was found in 21 papers, including proximity to infected animals, ingestion of infected material and potential association with a species known to carry influenza virus. Only three publications were found which presented a statistical measure of an epidemiological risk factor for the transmission of influenza between animal species. This review has identified a significant gap in knowledge regarding epidemiological risk factors for the transmission of influenza viruses between animal species.

Epidemiological risk factors of knowledge and preventive practice regarding avian influenza among poultry farmers and live bird traders in Ikorodu, Lagos State, Nigeria

Avian Influenza (AI) is an infectious disease of birds caused by type A influenza virus. The disease has a pandemic risk leading to death or depopulation of millions of birds. This study determined the risk factors that predict adequate knowledge and good preventive practice measures towards AI, among poultry farmers and live bird traders in Ikorodu, Lagos State, South-western Nigeria. A descriptive cross sectional survey was conducted with questionnaire on socio- demographics, knowledge of definition, and transmission of avian influenza administered to 244 respondents at interview. Descriptive, Chi-square and logistic regression analysis were carried out to explore associations between demographic characteristics, knowledge and preventive practice scores. All levels of significance were set at p < 0.05. The total knowledge score computed on a 25-item scale revealed a mean total knowledge of 9.9 (SD ± 6.6). Respondents aged <20 years, live bird traders and those with no formal education had the poorest knowledge. The total preventive practice score regarding avian influenza on a 9-item scale revealed a mean of 5.3 (SD ± 2.1). Younger respondents, live bird traders; those with no tertiary education and those spent <24 months in their profession had the poorest preventive practice score. Logistic regression analysis showed that increasing education (p < 0.05) significantly predicted adequate knowledge of avian influenza and good preventive practice among respondents. Poultry farmers and live bird traders, specially those with no formal education, should be aware of the transmission, seriousness and preventive measures of AI that will be reflected in the prevention and control of the disease in Nigeria.

H5 influenza, a global update

H5 influenza viruses have caused much alarm globally due to their high pathogenic potential. As yet we have not seen sustained spread of the virus amongst humans despite a high prevalence of the virus in avian populations. Nevertheless, isolated human cases of infection have demonstrated high mortality and there are substantial efforts being taken to monitor the evolution of the virus and to undertake preparedness activities. Here we review and discuss the evolution of the A/goose/Guangdong/1/96 (H5N1) virus with emphasis on recent events.

Human-livestock contacts and their relationship to transmission of zoonotic pathogens, a systematic review of literature

BACKGROUND

Micro-organisms transmitted from vertebrate animals - including livestock - to humans account for an estimated 60% of human pathogens. Micro-organisms can be transmitted through inhalation, ingestion, via conjunctiva or physical contact. Close contact with animals is crucial for transmission. The role of intensity and type of contact patterns between livestock and humans for disease transmission is poorly understood. In this systematic review we aimed to summarise current knowledge regarding patterns of human-livestock contacts and their role in micro-organism transmission.

METHODS

We included peer-reviewed publications published between 1996 and 2014 in our systematic review if they reported on human-livestock contacts, human cases of livestock-related zoonotic diseases or serological epidemiology of zoonotic diseases in human samples. We extracted any information pertaining the type and intensity of human-livestock contacts and associated zoonoses.

RESULTS

1522 papers were identified, 75 were included: 7 reported on incidental zoonoses after brief animal-human contacts (e.g. farm visits), 10 on environmental exposures and 15 on zoonoses in developing countries where backyard livestock keeping is still customary. 43 studies reported zoonotic risks in different occupations. Occupations at risk included veterinarians, culling personnel, slaughterhouse workers and farmers. For culling personnel, more hours exposed to livestock resulted in more frequent occurrence of transmission. Slaughterhouse workers in contact with live animals were more often positive for zoonotic micro-organisms compared to co-workers only exposed to carcasses. Overall, little information was available about the actual mode of micro-organism transmission.

CONCLUSIONS

Little is known about the intensity and type of contact patterns between livestock and humans that result in micro-organism transmission. Studies performed in occupational settings provide some, but limited evidence of exposure response-like relationships for livestock-human contact and micro-organism transmission. Better understanding of contact patterns driving micro-organism transmission from animals to humans is needed to provide options for prevention and thus deserves more attention.

Seroevidence for a High Prevalence of Subclinical Infection With Avian Influenza A(H5N1) Virus Among Workers in a Live-Poultry Market in Indonesia

Background. In Indonesia, highly pathogenic avian influenza A(H5N1) virus has become endemic in poultry and has caused sporadic deadly infections in human. Since 2012, we have conducted fixed-point surveillance of avian influenza viruses at a live-poultry market in East Java, Indonesia. In this study, we examined the seroprevalence of avian influenza A(H5N1) virus infection among market workers.

Methods. Sera were collected from 101 workers in early 2014 and examined for antibody activity against avian A(H5N1) Eurasian lineage virus by a hemagglutination-inhibition (HI) assay.

Results. By the HI assay, 84% of the sera tested positive for antibody activity against the avian virus. Further analysis revealed that the average HI titer in 2014 was 2.9-fold higher than in 2012 and that seroconversion occurred in 44% of paired sera (11 of 25) between 2012 and 2014. A medical history survey was performed in 2016; responses to questionnaires indicated that none of workers had had severe acute respiratory illness during 2013.

Conclusions. This study provides evidence of a high prevalence of avian A(H5N1) virus infection in 2013 among workers at a live-poultry market. However, because no instances of hospitalizations were reported, we can conclude the virus did not manifest any clinical symptoms in workers.

Infection Risk for Persons Exposed to Highly Pathogenic Avian Influenza A H5 Virus-Infected Birds, United States, December 2014-March 2015

Newly emerged highly pathogenic avian influenza (HPAI) A H5 viruses have caused outbreaks among birds in the United States. These viruses differ genetically from HPAI H5 viruses that previously caused human illness, most notably in Asia and Africa. To assess the risk for animal-to-human HPAI H5 virus transmission in the United States, we determined the number of persons with self-reported exposure to infected birds, the number with an acute respiratory infection (ARI) during a 10-day postexposure period, and the number with ARI who tested positive for influenza by real-time reverse transcription PCR or serologic testing for each outbreak during December 15, 2014-March 31, 2015. During 60 outbreaks in 13 states, a total of 164 persons were exposed to infected birds. ARI developed in 5 of these persons within 10 days of exposure. H5 influenza virus infection was not identified in any persons with ARI, suggesting a low risk for animal-to-human HPAI H5 virus transmission.

A Throat Lozenge Containing Amyl Meta Cresol and Dichlorobenzyl Alcohol Has a Direct Virucidal Effect on Respiratory Syncytial Virus, Influenza a and SARS-CoV

A potent virucidal mixture containing amyl metacresol and dichlorobenzyl alcohol at low pH inactivated enveloped respiratory viruses influenza A, respiratory synctial virus (RSV) and severe acute respiratory syndrome coronavirus (SARS-CoV) but not viruses with icosahedral symmetry, such as adenoviruses or rhinoviruses. A titre of approximately 3.5 log10 TCID50 was reduced to below the level of detection within two minutes. Electron microscopy of purified influenza A virus showed extensive clumping and morphological changes in spike configuration after contact with the virucidal mixture, but no overt destruction of the viral membrane. We conclude that, formulated as a lozenge, the mixture could have significant effects in reducing the infectivity of certain infectious viruses in the throat and presumably in cough droplets, thus reducing, theoretically, opportunities for person-to-person transmission.

Highly pathogenic Avian Influenza A(H5N1) virus infection among workers at live bird markets, Bangladesh, 2009-2010

Evidence of infection was low despite frequent exposure to infected poultry and low use of personal protective equipment.

The risk for influenza A(H5N1) virus infection is unclear among poultry workers in countries where the virus is endemic. To assess H5N1 seroprevalence and seroconversion among workers at live bird markets (LBMs) in Bangladesh, we followed a cohort of workers from 12 LBMs with existing avian influenza surveillance. Serum samples from workers were tested for H5N1 antibodies at the end of the study or when LBM samples first had H5N1 virus–positive test results. Of 404 workers, 9 (2%) were seropositive at baseline. Of 284 workers who completed the study and were seronegative at baseline, 6 (2%) seroconverted (7 cases/100 poultry worker–years). Workers who frequently fed poultry, cleaned feces from pens, cleaned food/water containers, and did not wash hands after touching sick poultry had a 7.6 times higher risk for infection compared with workers who infrequently performed these behaviors. Despite frequent exposure to H5N1 virus, LBM workers showed evidence of only sporadic infection.

Herd immunity and fatal cases of influenza among the population exposed to poultry and wild birds in Russian Asia in 2013-2014

In total 1,525 blood serum samples were collected in October, 2013 in Russian Asia from people who reside in territories that are at high risk for emergence of influenza viruses with pandemic potential. Presence of antibodies to influenza viruses in the sera was tested in hemagglutination inhibition test. None of the samples produced positive results with the antigens A/H5 and A/H7. Twelve strains of influenza A(H1N1pdm09) virus were isolated from people who died presumably from influenza during 2013-2014 epidemic season. All strains were similar to vaccine strain A/California/07/09 according to their antigenic properties and sensitivity to anti-neuraminidase drugs (oseltamivir and zanamivir). Genetic analysis revealed that all strains belong to group 6, subgroup 6B of influenza A(H1N1)pdm09 virus. Substitutions in HA1: S164F add E235K as well as E47G, A86V, K331R, N386K, N397K in NA, and K131E, N29S in NS1, and N29S, R34Q in NEP separate investigated strains into two groups: 1st group-A/Chita/1114/2014, A/Chita/1115/2014, A/Chita/853/2014, A/Barnaul/269/2014 and 2nd group-A/Chita/655/2014, A/Chita/656/2014, A/Chita/709/2014, A/Chita/873/2014. Mutation D222G in HA1, which is often associated with high morbidity of the illness, was present in strain A/Novosibirsk/114/2014. Substitution N386K in NA removes a potential N-glycosylation site in neuraminidases of A/Chita/1114/2014, A/Chita/1115/2014, A/Chita/853/2014, A/Barnaul/269/2014, A/Novosibirsk/114/2014, and A/Blagoveshensk/252/2014.

Changing risk awareness and personal protection measures for low to high pathogenic avian influenza in live-poultry markets in Taiwan, 2007 to 2012

Background

Outbreaks of low and high pathogenic avian influenza (LPAI, HPAI) H5N2 in chickens have occurred in Taiwan since 2003 and 2012, respectively. Fully understanding the different awareness, attitudes and protective behaviors adopted by workers in live-poultry markets (LPMWs) and local community residents (CRs) to face the challenges of LPAI and HPAI is very important to minimize viral adaptations to human populations.

Methods

A structural questionnaire containing information on respondents’ occupation, personal risk awareness, attitudes toward different policies, and preventative measures was administered. The two-stage survey (before and after HPAI H5N2 outbreaks) was conducted from 2007 to 2012, including: (1) 430 LPMWs and 418 CRs at LPMs from different geographical areas of Taiwan after the government announced outbreaks of LPAI H5N2 during 2007–2009, and (2) 73 LPMWs and 152 CRs at two LPMs in central Taiwan after the HPAI H5N2 outbreaks in 2012. The chi-squared test and logistic regression were applied for univariate and multivariate analyses, respectively.

Results

Before HPAI-H5N2 outbreaks, higher educated respondents demonstrated greater risk awareness and concerns regarding AI. However, LPM-workers protected themselves less from AI viruses (AIVs) and had lower acceptance of human or avian influenza vaccines. Most importantly, the participants who opposed (versus agreed with) the policy on banning live-poultry slaughtering at LPMs reported lower awareness of government prevention and control policies [Odds Ratio (OR): 0.76, 95 % Confidence Interval (CI): 0.56–1.01] or practiced preventive measures (OR: 0.42, 95 % CI: 0.25–0.70).

After HPAI-H5N2 outbreaks, the risk awareness about AI in central Taiwan significantly increased [LPAI to HPAI LPMWs: 34.6 to 65.6 %, p < 0.05; CRs: 44.0 to 76.5 %, p < 0.05] and LPMWs’ belief in the effectiveness of vaccination to prevent human or avian influenza virus infection strikingly decreased (92.3 to 68.5 %, p < 0.05).

Conclusions

Risk awareness depends on high or low pathogenicity of AIVs, working in LPMs, levels of education, age, and proximity to the sites of severe AI outbreaks. Regardless of novel LPAI or HPAI virus reassortants that pose public health risks, prompt and clear risk communication focusing on both correct information about AIVs and the most appropriate preventive measures are important for effective prevention of human infection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-0987-8) contains supplementary material, which is available to authorized users.

Knowledge, Attitudes, and Practices (KAP) Relating to Avian Influenza (H10N8) among Farmers' Markets Workers in Nanchang, China

Three cases of avian influenza virus H10N8 were reported in Nanchang, China, as of April 2014. To identify the knowledge, attitudes, and practices (KAP) related to H10N8 among farmers’ market workers, a cross-sectional survey was conducted in 63 farmers’ markets in Nanchang. Using the resulting data, characteristics of poultry and non-poultry workers’ knowledge, attitudes, and practice were described. Results suggest that interventions targeting high-risk workers should be developed and implemented by public health agencies to prevent the spread of H10N8. Additionally policies that encourage farmers’ market workers to receive influenza vaccine should be developed, adopted, and enforced.

Characterization of an H5N8 influenza A virus isolated from chickens during an outbreak of severe avian influenza in Japan in April 2014

A highly pathogenic avian influenza virus (HPAIV) of subtype H5N8, A/chicken/Kumamoto/1-7/2014, was isolated from a Japanese chicken farm during an outbreak in April 2014. Phylogenetic analysis revealed that this virus belonged to HA clade 2.3.4.4. All eight genomic segments showed high sequence similarity to those of the H5N8 subtype HPAIVs A/broiler duck/Korea/Buan2/2014 and A/baikal teal/Korea/Donglim3/2014, which were isolated in Korea in January 2014. Intranasal experimental infection of chickens and ducks with A/chicken/Kumamoto/1-7/2014 was performed to assess the pathogenicity of the virus in chickens and the potential for waterfowl to act as a virus reservoir and carrier. A high-titer virus challenge (10(6) EID50 per animal) was lethal in chickens, but they were unaffected by lower virus doses (10(2) EID50 or 10(4) EID50 per animal). Virus challenge at all doses examined was found to result in asymptomatic infection of ducks. An HI assay revealed that A/chicken/Kumamoto/1-7/2014 possessed relatively low cross-reactivity with H5 viruses belonging to clades other than clade 2.3.4.4. These results suggest that waterfowl may be able to spread the virus even if they possess antibodies resulting from a previous infection with H5 HPAIV that was antigenically distinguishable from viruses belonging to clade 2.3.4.4.

Serological comparison of antibodies to avian influenza viruses, subtypes H5N2, H6N1, H7N3 and H7N9 between poultry workers and non-poultry workers in Taiwan in 2012

In Taiwan, avian influenza virus (AIV) subtypes H5N2, H6N1 and H7N3 have been identified in domestic poultry, and several strains of these subtypes have become endemic in poultry. To evaluate the potential of avian-to-human transmission due to occupational exposure, an exploratory analysis of AIV antibody status in poultry workers was conducted. We enrolled 670 poultry workers, including 335 live poultry vendors (LPVs), 335 poultry farmers (PFs), and 577 non-poultry workers (NPWs). Serum antibody titres against various subtypes of viruses were analysed and compared. The overall seropositivity rates in LPVs and PFs were 2·99% (10/335) and 1·79% (6/335), respectively, against H5N2; and 0·6% (2/335) and 1·19% (4/335), respectively, for H7N3 virus. Of NPWs, 0·35% (2/577) and 0·17% (1/577) were seropositive for H5N2 and H7N3, respectively. Geographical analysis revealed that poultry workers whose workplaces were near locations where H5N2 outbreaks in poultry have been reported face greater risks of being exposed to viruses that result in elevated H5N2 antibody titres. H6N1 antibodies were detected in only one PF, and no H7N9 antibodies were found in the study subjects. Subclinical infections caused by H5N2, H6N1 and H7N3 viruses were thus identified in poultry workers in Taiwan. Occupational exposure is associated with a high risk of AIV infection, and the seroprevalence of particular avian influenza strains in humans reflects the endemic strains in poultry in this region.

Personal Protective Equipment Use and Handwashing Among Animal Farmers: A Multi-site Assessment

The goal of this study was to compare and contrast the use of personal protective equipment (PPE) and the practice of handwashing among participants of four studies assessing poultry and swine farms in the midwestern United States and in Thailand. This largely descriptive exercise was designed to assess and compare the frequency of these protective practices among the study populations. There were a total of 1113 surveys analyzed across the four studies. The respondents included workers in direct contact with animals as well as flock owners and veterinarians tending to farms. Handwashing was the most common practice observed among all participants with 42% "always" and 35% "sometimes" washing their hands after contact with the animals. This practice was least common among Minnesota swine workers. Even Thai poultry farmers, who demonstrated the lowest overall PPE use, reported a higher frequency of handwashing. Mask use during animal farming activities ("always" or "sometimes") was least commonly practiced, ranging from 1% in Thailand to 26% among backyard poultry farmers in Minnesota. Minnesota poultry and swine farmers had similar frequencies of mask (26%) and glove use (51% and 49%). All other comparisons differed significantly across the four sites (p-values <0.05). The use of PPE in animal farming differed by study location and is likely related to prevalent norms in the respective regions. Overall, the use of PPE did not appear to be influenced by the particular animal (poultry or swine) being farmed. These findings may prove useful to regulating bodies and farm owners in formulating policy or planning strategies for improving personal hygiene practices in animal farming and preparing for influenza and other potential zoonotic disease outbreaks.

Seasonal influenza vaccination is the strongest correlate of cross-reactive antibody responses in migratory bird handlers

Avian species are reservoirs of influenza A viruses and could harbor viruses with significant pandemic potential. We examined the antibody and cellular immune responses to influenza A viruses in field or laboratory workers with a spectrum of occupational exposure to avian species for evidence of zoonotic infections. We measured the seroprevalence and T cell responses among 95 individuals with various types and degrees of prior field or laboratory occupational exposure to wild North American avian species using whole blood samples collected in 2010. Plasma samples were tested using endpoint enzyme-linked immunosorbent assay (ELISA) and hemagglutination (HA) inhibition (HAI) assays to subtypes H3, H4, H5, H6, H7, H8, and H12 proteins. Detectable antibodies were found against influenza HA antigens in 77% of individuals, while 65% of individuals tested had measurable T cell responses (gamma interferon [IFN-γ] enzyme-linked immunosorbent spot assay [ELISPOT]) to multiple HA antigens of avian origin. To begin defining the observed antibody specificities, Spearman rank correlation analysis showed that ELISA responses, which measure both head- and stalk-binding antibodies, do not predict HAI reactivities, which measure primarily head-binding antibodies. This result suggests that ELISA titers can report cross-reactivity based on the levels of non-head-binding responses. However, the strongest positive correlate of HA-specific ELISA antibody titers was receipt of seasonal influenza virus vaccination. Occupational exposure was largely uncorrelated with serological measures, with the exception of individuals exposed to poultry, who had higher levels of H7-specific antibodies than non-poultry-exposed individuals. While the cohort had antibody and T cell reactivity to a broad range of influenza viruses, only occupational exposure to poultry was associated with a significant difference in antibody levels to a specific subtype (H7). There was no evidence that T cell assays provided greater specificity for the detection of zoonotic infection. However, influenza vaccination appears to promote cross-reactive antibodies and may provide enhanced protection to novel influenza viruses.

IMPORTANCE

Annual vaccinations are necessary to ameliorate influenza disease due to drifted viral variants that emerge in the population. Major shifts in the antigenicity of influenza viruses can result in immunologically distinct viruses that can cause more severe disease in humans. Historically, genetic reassortment between avian, swine, or human influenza viruses has caused influenza pandemics in humans several times in the last century. Therefore, it is important to design vaccines to elicit broad protective responses to influenza infections. Because avian influenza viruses have an important role in emerging infections, we tested whether occupational exposure to birds can elicit immune responses to avian influenza viruses in humans. Instead of a specific occupational exposure, the strongest association of enhanced cross-reactive antibody responses was receipt of seasonal influenza vaccination. Therefore, individuals with preexisting immune responses to seasonal human influenza viruses have substantial cross-reactive antibody and T cell responses that may lead to enhanced protection to novel influenza viruses.

Characterizing wild bird contact and seropositivity to highly pathogenic avian influenza A (H5N1) virus in Alaskan residents

BACKGROUND

Highly pathogenic avian influenza A (HPAI) H5N1 viruses have infected poultry and wild birds on three continents with more than 600 reported human cases (59% mortality) since 2003. Wild aquatic birds are the natural reservoir for avian influenza A viruses, and migratory birds have been documented with HPAI H5N1 virus infection. Since 2005, clade 2.2 HPAI H5N1 viruses have spread from Asia to many countries.

OBJECTIVES

We conducted a cross-sectional seroepidemiological survey in Anchorage and western Alaska to identify possible behaviors associated with migratory bird exposure and measure seropositivity to HPAI H5N1.

METHODS

We enrolled rural subsistence bird hunters and their families, urban sport hunters, wildlife biologists, and a comparison group without bird contact. We interviewed participants regarding their exposures to wild birds and collected blood to perform serologic testing for antibodies against a clade 2.2 HPAI H5N1 virus strain.

RESULTS

Hunters and wildlife biologists reported exposures to wild migratory birds that may confer risk of infection with avian influenza A viruses, although none of the 916 participants had evidence of seropositivity to HPAI H5N1.

CONCLUSIONS

We characterized wild bird contact among Alaskans and behaviors that may influence risk of infection with avian influenza A viruses. Such knowledge can inform surveillance and risk communication surrounding HPAI H5N1 and other influenza viruses in a population with exposure to wild birds at a crossroads of intercontinental migratory flyways.

One health: the Hong Kong experience with avian influenza

The occurrence of avian influenza A(H5N1) in Hong Kong in 1997 led to the development of a "One-Health" approach to deal with emerging infectious diseases that has been applied to other emergent diseases such as SARS and the pandemic H1N1 2009. Evaluation of poultry marketing and production systems and investigations at the animal-human interface, led to defining the routes of human exposure to avian influenza and factors that allowed virus to multiply and persist. Active and systematic surveillance of apparently healthy as well as diseased poultry and wild birds provided evidence of ongoing virus evolution in the wider region. Epidemiological studies, supplemented with molecular epidemiology, helped to elucidate the role of the poultry marketing system and live poultry markets in the persistence of avian influenza viruses and provided evidence for the impact of interventions designed to interrupt virus transmission. Enhanced bio-security, active surveillance together with targeted and evidence-based interventions in the poultry production, and marketing system together with poultry vaccination has prevented further human H5N1 disease and minimized outbreaks of poultry disease in Hong Kong. Similar strategies have led to the understanding of the emergence of SARS and provided options for preventing the re-emergence of this disease. Surveillance of influenza in swine has provided insights into the emergence of the 2009 pandemic, to the reverse zoonosis of the pandemic virus from humans to swine and to the emergence of novel reassortant viruses within swine. "One Health" strategies are not "cost-free" and require sensitive implementation to optimize food-safety and food security, while safeguarding the economics of animal husbandry and the environment and remaining sensitive to cultural practices.

Disease severity is associated with differential gene expression at the early and late phases of infection in nonhuman primates infected with different H5N1 highly pathogenic avian influenza viruses

Occasional transmission of highly pathogenic avian H5N1 influenza viruses to humans causes severe pneumonia with high mortality. To better understand the mechanisms via which H5N1 viruses induce severe disease in humans, we infected cynomolgus macaques with six different H5N1 strains isolated from human patients and compared their pathogenicity and the global host responses to the virus infection. Although all H5N1 viruses replicated in the respiratory tract, there was substantial heterogeneity in their replicative ability and in the disease severity induced, which ranged from asymptomatic to fatal. A comparison of global gene expression between severe and mild disease cases indicated that interferon-induced upregulation of genes related to innate immunity, apoptosis, and antigen processing/presentation in the early phase of infection was limited in severe disease cases, although interferon expression was upregulated in both severe and mild cases. Furthermore, coexpression analysis of microarray data, which reveals the dynamics of host responses during the infection, demonstrated that the limited expression of these genes early in infection led to a failure to suppress virus replication and to the hyperinduction of genes related to immunity, inflammation, coagulation, and homeostasis in the late phase of infection, resulting in a more severe disease. Our data suggest that the attenuated interferon-induced activation of innate immunity, apoptosis, and antigen presentation in the early phase of H5N1 virus infection leads to subsequent severe disease outcome.

IMPORTANCE

Highly pathogenic avian H5N1 influenza viruses sometimes transmit to humans and cause severe pneumonia with ca. 60% lethality. The continued circulation of these viruses poses a pandemic threat; however, their pathogenesis in mammals is not fully understood. We, therefore, investigated the pathogenicity of six H5N1 viruses and compared the host responses of cynomolgus macaques to the virus infection. We identified differences in the viral replicative ability of and in disease severity caused by these H5N1 viruses. A comparison of global host responses between severe and mild disease cases identified the limited upregulation of interferon-stimulated genes early in infection in severe cases. The dynamics of the host responses indicated that the limited response early in infection failed to suppress virus replication and led to hyperinduction of pathological condition-related genes late in infection. These findings provide insight into the pathogenesis of H5N1 viruses in mammals.

Quantification of viral proteins of the avian H7 subtype of influenza virus: an isotope dilution mass spectrometry method applicable for producing more rapid vaccines in the case of an influenza pandemic

Vaccination is the most effective means to prevent influenza and its serious complications. Influenza viral strains undergo rapid mutations of the surface proteins hemagglutinin (HA) and neuraminidase (NA) requiring vaccines to be frequently updated to include current circulating strains. It is nearly impossible to predict which strains will be circulating in the next influenza season. It is, therefore, imperative that the process of producing a vaccine be streamlined and as swift as possible. We have developed an isotope dilution mass spectrometry (IDMS) method to quantify HA and NA in H7N7, H7N2, and H7N9 influenza. The IDMS method involves enzymatic digestion of viral proteins and the specific detection of evolutionarily conserved target peptides. The four target peptides that were initially chosen for analysis of the HA protein of H7N2 and H7N7 subtypes were conserved and available for analysis of the H7N9 subtype that circulated in China in the spring of 2013. Thus, rapid response to the potential pandemic was realized. Quantification of a protein is performed by employing multiple peptides to ensure that the enzymatic digestion of the protein is efficient in the region of the target peptides, verify the accuracy of the measurement, and provide flexibility in the case of amino acid changes among newly emerging strains. The IDMS method is an accurate, sensitive, and selective method to quantify the amount of HA and NA antigens in primary liquid standards, crude allantoic fluid, purified virus samples, and final vaccine presentations.

Complete Genome Sequence of a Mixed-Subtype (H5N1 and H6N6) Avian Influenza Virus Isolated from a Duck in Hunan Province, China

We isolated an avian influenza virus, A/duck/Hunan/747/2011(mixed), which included the H5N1 and H6N6 subtypes, from a duck in China. Phylogenetic analysis indicates that the H5 hemagglutinin (HA) gene belongs to clade 2.3.2.1, the H6 HA gene belongs to the group II lineage, and the other internal genes show different recombination events.

Investigation of avian influenza infections in wild birds, poultry and humans in Eastern Dongting Lake, China

We investigated avian influenza infections in wild birds, poultry, and humans at Eastern Dongting Lake, China. We analyzed 6,621 environmental samples, including fresh fecal and water samples, from wild birds and domestic ducks that were collected from the Eastern Dongting Lake area from November 2011 to April 2012. We also conducted two cross-sectional serological studies in November 2011 and April 2012, with 1,050 serum samples collected from people exposed to wild birds and/or domestic ducks. Environmental samples were tested for the presence of avian influenza virus (AIV) using quantitative PCR assays and virus isolation techniques. Hemagglutination inhibition assays were used to detect antibodies against AIV H5N1, and microneutralization assays were used to confirm these results. Among the environmental samples from wild birds and domestic ducks, AIV prevalence was 5.19 and 5.32%, respectively. We isolated 39 and 5 AIVs from the fecal samples of wild birds and domestic ducks, respectively. Our analysis indicated 12 subtypes of AIV were present, suggesting that wild birds in the Eastern Dongting Lake area carried a diverse array of AIVs with low pathogenicity. We were unable to detect any antibodies against AIV H5N1 in humans, suggesting that human infection with H5N1 was rare in this region.

Brief literature review for the WHO global influenza research agenda--highly pathogenic avian influenza H5N1 risk in humans

Highly pathogenic avian influenza A H5N1 viruses remain a significant health threat to humans given the continued rare occurrence of human cases with a high case fatality rate. This brief literature review summarizes available evidence of risk factors for H5N1 infection in humans and updates a recent systematic review published in early 2011. Several epidemiologic studies have been published to evaluate the risk factors for H5N1 infection in humans, including contact with poultry and poultry products and non-poultry-related contact such as from H5N1-contaminated water. While most H5N1 cases are attributed to exposure to sick poultry, it is unclear how many may be due to human-to-human transmission. The collective results of published literature suggest that transmission risk of H5N1 from poultry to humans may be highest among individuals who may have been in contact with the highest potential concentrations of virus shed by poultry. This suggests that there may be a threshold of virus concentration needed for effective transmission and that circulating H5N1 strains have not yet mutated to transmit readily from either poultry to human or from human to human. However, the mode of potential transmission can be quite varied throughout different countries and by study with exposures ranging from visiting a wet market, preparing infected poultry for consumption, to swimming or bathing in ponds frequented by poultry. Several important data gaps remain in the understanding of the epidemiology of H5N1 in humans and limit our ability to interpret the results of the available H5N1 seroepidemiologic studies.

Seroprevalence survey of avian influenza A (H5) in wild migratory birds in Yunnan Province, Southwestern China

BACKGROUND

Highly pathogenic avian influenza virus (HPAIV) is a highly contagious disease which is a zoonotic pathogen of significant economic and public health concern. The outbreaks caused by HPAIV H5N1 of Asian origin have caused animal and human disease and mortality in several countries of Southeast Asia, such as Bangladesh, Cambodia, China, India, Indonesia, Laos, Myanmar, Thailand and Viet Nam. For the first time since 1961, this HPAIV has also caused extensive mortality in wild birds and has sparked debate of the role wild birds have played in the spread of this virus. Other than confirmed mortality events, little is known of this virus in wild birds. There is no report on the seroprevalence of avian influenza H5 infection in wild migratory birds in Yunnan Province. In this study we examined live wild birds in Yunnan Province for H5 specific antibody to better understand the occurrence of this disease in free living birds.

METHODS

Sera from 440 wild birds were collected from in Kunming and Northern Ailaoshan of Yunnan Province, Southwestern China, and assayed for H5 antibodies using the hemagglutination inhibition (HI) assays.

RESULTS

The investigation revealed that the seroprevalence of avian influenza H5 was as following: Ciconiiformes 2.6%, Strigiformes 13.04%, Passeriformes 20%, Cuculiformes 21.74%, Gruiformes 0%, Columbiformes 0%, Charadriiformes 0% and Coraciiformes 0%. Statistical analyses showed that there was a significant difference of prevalence between the orders (P < 0.01). Specific avian influenza H5 antibodies were detected in 23 of 440 (5.23%) sera. Mean HI titer 23 positive sera against H5 were 5.4 log₂.

CONCLUSIONS

The results of the present survey indicated that the proportion of wild birds had previously infected AIV H5 at other times of the year. To our knowledge, this is the first seroprevalence report of avian influenza H5 infection in wild migratory birds in China' s southwestern Yunnan Province. The results of the present survey have significant public health concerns.

H1N1, but not H3N2, influenza A virus infection protects ferrets from H5N1 encephalitis

Seasonal influenza causes substantial morbidity and mortality because of efficient human-to-human spread. Rarely, zoonotic strains of influenza virus spread to humans, where they have the potential to mediate new pandemics with high mortality. We studied systemic viral spread after intranasal infection with highly pathogenic avian influenza virus (H5N1 [A/Viet Nam/1203/2004]) in ferrets with or without prior pandemic H1N1pdm09 (A/Mexico/4108/2009) or H3N2 (A/Victoria/361/2011) infection. After intranasal challenge with H5N1 influenza virus, naive ferrets rapidly succumbed to systemic infection. Animals challenged with H5N1 influenza virus greater than 3 months after recovering from an initial H1N1pdm09 infection survived H5N1 virus challenge and cleared virus from the respiratory tract 4 days after infection. However, a prolonged low-level infection of hematopoietic elements in the small bowel lamina propria, liver, and spleen was present for greater than 2 weeks postinfection, raising the potential for reassortment of influenza genes in a host infected with multiple strains of influenza. Animals previously infected with an H3N2 influenza virus succumbed to systemic disease and encephalitis after H5N1 virus challenge. These results indicate prior infection with different seasonal influenza strains leads to radically different protection from H5N1 challenge and fatal encephalitis.

IMPORTANCE

Seasonal influenza is efficiently transmitted from human to human, causing substantial morbidity and mortality. Rarely, zoonotic strains of influenza virus spread to humans, where they have the potential to mediate new pandemics with high mortality. Infection of naive ferrets with H5N1 avian influenza virus causes a rapid and lethal systemic disease. We studied systemic H5N1 viral spread after infection of ferrets with or without prior exposure to either of two seasonal influenza virus strains, H1N1 and H3N2. Ferrets previously infected with H1N1 survive H5N1 challenge while those previously infected with H3N2 die of encephalitis. However ferrets protected from lethal H5N1 infection develop persistent low-level infection of the small intestine, liver, or spleen, providing a nidus for future viral strain recombination. The mechanism by which prior infection with specific strains of seasonal influenza virus protect from lethal H5N1 challenge needs to be elucidated in order to design effective immunization and treatments.