Interpreting the transmissibility of the avian influenza A(H7N9) infection from 2013 to 2015 in Zhejiang Province, China

Public awareness, acceptability and risk perception about infectious diseases dual-use research of concern: a cross-sectional survey

OBJECTIVES

In this study, we aimed to measure the awareness, acceptability and perceptions of current issues in biosecurity posed by infectious diseases dual-use research of concern (DURC) in the community. DURC is conducted today in many locations around the world for the benefit of humanity but may also cause harm through either a laboratory accident or deliberate misuse. Most DURC is approved by animal ethics committees, which do not typically consider harm to humans. Given the unique characteristics of contagion and the potential for epidemics and pandemics, the community is an important stakeholder in DURC.

DESIGN

Self-administered web-based cross-sectional survey.

PARTICIPANTS

Participants over the age of 18 in Australia and 21 in the USA were included in the survey. A total of 604 participants completed the study. The results of 52 participants were excluded due to potential biases about DURC stemming from their employment as medical researchers, infectious diseases researchers or law enforcement professionals, leaving 552 participants. Of those, 274 respondents resided in Australia and 278 in the USA.

OUTCOMES

Baseline awareness, acceptability and perceptions of current issues surrounding DURC. Changes in perception from baseline were measured after provision of information about DURC.

RESULTS

Presurvey, 77% of respondents were unaware of DURC and 64% found it unacceptable or were unsure. Two-thirds of respondents did not change their views. The baseline perception of high risk for laboratory accidents (29%) and deliberate bioterrorism (34%) was low but increased with increasing provision of information (42% and 44% respectively, p<0.001), with men more accepting of DURC (OR=1.79, 95% CI 1.25 to 2.57, p=0.002). Postsurvey, higher education predicted lower risk perception of laboratory accidents (OR=0.56, 95% CI 0.34 to 0.93, p=0.02) and bioterrorism (OR=0.48, 95% CI 0.29 to 0.80, p=0.004).

CONCLUSION

The community is an important stakeholder in infectious diseases DURC but has a low awareness of this kind of research. Only a minority support DURC, and this proportion decreased with increasing provision of knowledge. There were differences of opinion between age groups, gender and education levels. The community should be informed and engaged in decisions about DURC.

Comparison of methods to Estimate Basic Reproduction Number (R 0) of influenza, Using Canada 2009 and 2017-18 A (H1N1) Data

Background

The basic reproduction number (R ₀) has a key role in epidemics and can be utilized for preventing epidemics. In this study, different methods are used for estimating R ₀'s and their vaccination coverage to find the formula with the best performance.

Materials and Methods

We estimated R ₀ for cumulative cases count data from April 18 to July 6, 2009 and 35-2017 to 34-2018 weeks in Canada: maximum likelihood (ML), exponential growth rate (EG), time-dependent reproduction numbers (TD), attack rate (AR), gamma-distributed generation time (GT), and the final size of the epidemic. Gamma distribution with mean and standard deviation 3.6 ± 1.4 is used as GT.

Results

The AR method obtained a R _{0 (}95% confidence interval [CI]) value of 1.116 (1.1163, 1.1165) and an EG (95%CI) value of 1.46 (1.41, 1.52). The R ₀ (95%CI) estimate was 1.42 (1.27, 1.57) for the obtained ML, 1.71 (1.12, 2.03) for the obtained TD, 1.49 (1.0, 1.97) for the gamma-distributed GT, and 1.00 (0.91, 1.09) for the final size of the epidemic. The minimum and maximum vaccination coverage were related to AR and TD methods, respectively, where the TD method has minimum mean squared error (MSE). Finally, the R ₀ (95%CI) for 2018 data was 1.52 (1.11, 1.94) by TD method, and vaccination coverage was estimated as 34.2%.

Conclusion

For the purposes of our study, the estimation of TD was the most useful tool for computing the R ₀, because it has the minimum MSE. The estimation R ₀ > 1 indicating that the epidemic has occurred. Thus, it is required to vaccinate at least 41.5% to prevent and control the next epidemic.

Virus-induced pathogenesis, vaccine development, and diagnosis of novel H7N9 avian influenza A virus in humans: a systemic literature review

H7N9 avian influenza virus (AIV) caused human infections in 2013 in China. Phylogenetic analyses indicate that H7N9 AIV is a novel reassortant strain with pandemic potential. We conducted a systemic review regarding virus-induced pathogenesis, vaccine development, and diagnosis of H7N9 AIV infection in humans. We followed PRISMA guidelines and searched PubMed, Web of Science, and Google Scholar to identify relevant articles published between January 2013 and December 2018. Pathogenesis data indicated that H7N9 AIV belongs to low pathogenic avian influenza, which is mostly asymptomatic in avian species; however, H7N9 induces high mortality in humans. Sporadic human infections have recently been reported, caused by highly pathogenic avian influenza viruses detected in poultry. H7N9 AIVs resistant to adamantine and oseltamivir cause severe human infection by rapidly inducing progressive acute community-acquired pneumonia, multiorgan dysfunction, and cytokine dysregulation; however, mechanisms via which the virus induces severe syndromes remain unclear. An H7N9 AIV vaccine is lacking; designs under evaluation include synthesized peptide, baculovirus-insect system, and virus-like particle vaccines. Molecular diagnosis of H7N9 AIVs is suggested over conventional assays, for biosafety reasons. Several advanced or modified diagnostic assays are under investigation and development. We summarized virus-induced pathogenesis, vaccine development, and current diagnostic assays in H7N9 AIVs.

Identification of meteorological factors associated with human infection with avian influenza A H7N9 virus in Zhejiang Province, China

BACKGROUND

Since the first reported human infection with an avian-origin influenza A (H7N9) virus in China in early 2013, there have been recurrent outbreaks of the virus in the country. Previous studies have shown that meteorological factors are associated with the risk of human infection with the virus; however, their possible nonlinear and lagged effects were not commonly taken into account.

METHOD

To quantify the effect of meteorological factors on the risk of human H7N9 infection, daily laboratory-confirmed cases of human H7N9 infection and meteorological factors including total rainfall, average wind speed, average temperature, average relative humidity, and sunshine duration of the 11 sub-provincial/prefecture cities in Zhejiang during the first four outbreaks (13 March 2013-30 June 2016) were analyzed. Separate models were built for the 6 sub-provincial/prefecture cities with the greatest number of reported cases using a combination of logistic generalized additive model and distributed lag nonlinear models, which were then pooled by a multivariate meta-regression model to determine their overall effects.

RESULTS

According to the meta-regression model, for rainfall, the log adjusted overall cumulative odds ratio was statistically significant when log of rainfall was >4.0, peaked at 5.3 with a value of 12.42 (95% confidence intervals (CI): [3.23, 21.62]). On the other hand, when wind speed was 2.1-3.0 m/s or 6.3-7.1 m/s, the log adjusted overall cumulative odds ratio was statistically significant, peaked at 7.1 m/s with a value of 6.75 (95% CI: [0.03, 13.47]). There were signs of nonlinearity and lag effects in their associations with the risk of infection.

CONCLUSION

As rainfall and wind speed were found to be associated with the risk of human H7N9 infection, weather conditions should be taken into account when it comes to disease surveillance, allowing prompt actions when an outbreak takes place.

Development of a universal influenza vaccine using hemagglutinin stem protein produced from Pichia pastoris

The development of a universal influenza vaccine has become a major effort to combat the high mutation rate of influenza. To explore the use of the highly conserved stem region of hemagglutinin (HA) as a universal vaccine, we produced HA-stem-based protein using yeast expression systems. The glycosylation effects on the immunogenicity and protection activities were investigated. The yield of the A/Brisbane/59/2007 HA stem produced from Pichia pastoris reached 100 mg/l. The immunogenicity of HA stem proteins in various glycoforms was further investigated and compared. All glycoforms of the HA stem protein can induce cross-reactive antibody responses, antibody-dependent cellular cytotoxicity (ADCC)-mediated protection as well as T-cell responses, with broad protection in mice. The monoglycosylated form of the A/Brisbane/59/2007 HA stem produced in yeast, together with the glycolipid C34 as the adjuvant, can elicit greater ADCC responses, better neutralizing activities against heterologous strains, and broader protection in mice.

An increasing trend of rural infections of human influenza A (H7N9) from 2013 to 2017: A retrospective analysis of patient exposure histories in Zhejiang province, China

BACKGROUND

Although investigations have shown that closing live poultry markets (LPMs) is highly effective in controlling human influenza A (H7N9) infections, many of the urban LPMs were shut down, but rural LPMs remained open. This study aimed to compare the proportional changes between urban and rural infections in the Zhejiang province from 2013 to 2017 by analyzing the exposure histories of human cases.

METHODS

All laboratory-confirmed cases of H7N9 from 2013 (the first wave) to 2017 (the fifth wave) in the Zhejiang province of China were analyzed. Urban and rural infections were defined based on the locations of poultry exposure (direct and indirect) in urban areas (central towns) and rural areas (towns and villages on the outskirts of cities). A Chi-square trend test was used to compare the proportional trend between urban and rural infections over time and logistic regression was used to obtain the odds ratio by years.

RESULTS

From 2013 to 2017, a statistically significant trend in rural infections was observed (p <0.01). The incremental odds ratio by years of rural infections was 1.59 with 95% confidence intervals of 1.34 to 1.86. Each year, significant increases in the proportion of live poultry transactions in LPMS and poultry processing plants were detected in conjunction with an increased proportion of urban and rural infections.

CONCLUSION

The empirical evidence indicated a need for heightened infection control measures in rural areas, such as serving rural farms and backyards as active surveillance points for the H7N9 virus. Other potential interventions such as the vaccination of poultry and extending the closure of LPMs to the provincial level require further careful investigations.

AVIAN INFLUENZA A H7N9 VIRUS HAS BEEN ESTABLISHED IN CHINA

In March 2013, a novel avian-origin influenza A H7N9 virus was identified among human patients in China and a total of 124 human cases with 24 related deaths were confirmed by May 2013. From November 2013 to July 2017, H7N9 broke out four more times in China. A deterministic model is proposed to study the transmission dynamics of the avian influenza A H7N9 virus between wild and domestic birds and from birds to humans, and is applied to simulate the open data on numbers of the infected human cases and related deaths reported from March to May 2013 and from November 2013 to June 2014 by the Chinese Center for Disease Control and Prevention. The basic reproduction number [Formula: see text] is estimated and sensitivity analysis of [Formula: see text] in terms of model parameters is performed. Taking into account the fact that it broke out again from November 2014 to June 2015, from November 2015 to July 2016, and from October 2016 to July 2017, we believe that H7N9 virus has been well established in birds and will likely cause regular outbreaks in humans again in the future. Control measures for the future spread of H7N9 include (i) reducing the transmission opportunities between wild birds and domestic birds, (ii) closing or monitoring the retail live-poultry markets in the infected areas, and (iii) culling the infected domestic birds in the epidemic regions.

ANALYSIS OF AVIAN INFLUENZA A (H7N9) MODEL BASED ON THE LOW PATHOGENICITY IN POULTRY

The avian influenza A (H7N9) virus is one subtype of influenza viruses, which has previously been isolated only in birds. Recently, an outbreak of a new avian influenza (H7N9) in China has resulted in numerous infections and high mortality in the humans. The H7N9 virus is low pathogenic in poultry and high pathogenic in human and that is critically different from other avian influenza viruses. An increasing number of the new H7N9 cases and the high mortality have caused a serious global concern. Here, based on the reported data, we propose and analyze an SE-SEIS avian–human influenza model. We prove the global stability results for both the disease-free equilibrium point and the endemic equilibrium point by using a general Bendixson–Dulac theorem. Our reported theoretical results of this paper are expected to help in exploring the development of efficient methods to controlling the spread of avian influenza A(H7N9).

Influenza A H5N1 and H7N9 in China: A spatial risk analysis

Background

Zoonotic avian influenza poses a major risk to China, and other parts of the world. H5N1 has remained endemic in China and globally for nearly two decades, and in 2013, a novel zoonotic influenza A subtype H7N9 emerged in China. This study aimed to improve upon our current understanding of the spreading mechanisms of H7N9 and H5N1 by generating spatial risk profiles for each of the two virus subtypes across mainland China.

Methods and findings

In this study, we (i) developed a refined data set of H5N1 and H7N9 locations with consideration of animal/animal environment case data, as well as spatial accuracy and precision; (ii) used this data set along with environmental variables to build species distribution models (SDMs) for each virus subtype in high resolution spatial units of 1km² cells using Maxent; (iii) developed a risk modelling framework which integrated the results from the SDMs with human and chicken population variables, which was done to quantify the risk of zoonotic transmission; and (iv) identified areas at high risk of H5N1 and H7N9 transmission. We produced high performing SDMs (6 of 8 models with AUC > 0.9) for both H5N1 and H7N9. In all our SDMs, H7N9 consistently showed higher AUC results compared to H5N1, suggesting H7N9 suitability could be better explained by environmental variables. For both subtypes, high risk areas were primarily located in south-eastern China, with H5N1 distributions found to be more diffuse and extending more inland compared to H7N9.

Conclusions

We provide projections of our risk models to public health policy makers so that specific high risk areas can be targeted for control measures. We recommend comparing H5N1 and H7N9 prevalence rates and survivability in the natural environment to better understand the role of animal and environmental transmission in human infections.

Simultaneous detection of influenza A subtypes of H3N2 virus, pandemic (H1N1) 2009 virus and reassortant avian H7N9 virus in humans by multiplex one-step real-time RT-PCR assay

Background

Influenza A virus is a leading causative pathogen of human acute respiratory infection. Recently, the co-circulation of pandemic (H1N1) 2009 and seasonal H3N2 viruses was reported, and sporadic cases with reassortant avian H7N9 virus are continually reported in China. We aimed to establish a multiplex one-step real-time reverse transcription-polymerase chain reaction (rRT-PCR) assay to simultaneously detect and discriminate FluA subtypes, including human seasonal H3N2 virus, pandemic (H1N1) 2009 virus and reassortant avian H7N9 virus, in one reaction tube.

Methods

Clinical samples, including throat swabs and sputum, were collected from the patients with influenza-like illness (ILIs). Total viral RNA from each sample or viral culture was extracted, and the specific detection of FluA virus and its subtypes was performed using a multiplex rRT-PCR assay.

Results

The limitation of detection (LOD) of the multiplex assay was 5.4 × 10⁻² 50% tissue culture infective dose (TCID₅₀) per reaction or 4.8 × 10¹ copies per reaction for each virus of the three viruses. For simultaneously detecting the three viruses, the LOD was 1.8 × 10⁻² TCID₅₀ per reaction or 1.6 × 10 copies per reaction for testing the total FluA virus RNA and 5.6 × 10⁻² TCID₅₀ per reaction or 5.1 × 10 copies per reaction for the H3, H1, and H7 genes in one reaction tube. The multiplex assay specifically detected these viruses, and no cross-reaction with other pathogens was found. Moreover, the assay had reliable clinical sensitivity (100%) and valuable clinical specificity (>95%). The detection of FluA with the matrix (M) gene contributed to the further determination of these subtypes, and the Rnase P gene (RP) was considered an internal control to favourably evaluate the quality of the clinical samples.

Conclusions

These findings indicate that the multiplex assay can simultaneously detect and discriminate FluA subtypes with reliable sensitivity and specificity, which is required for the early clinical diagnosis and viral surveillance of patients with FluA infection.