珠海市2007-2008年乙型流感病毒基因特性分析

目的了解珠海市近两年乙型流感病毒的基因变异情况。方法采集珠海市流感样病例样本进行流感病毒的分离和鉴定,并对分离到的乙型流感病毒进行核酸的提取,采用逆转录-聚合酶链反应(RT-PCR)扩增病毒基因后进行病毒血凝素HA1基因核苷酸序列测定,用Mega、DNA Star、GeneDoc软件对测序结果进行分析处理,并与WHO推荐的疫苗株基因序列进行比对。结果 2007-2008年分离的乙型流感毒株分属于Yamagata系和Victoria系两个谱系,谱系内毒株间距离很近。Yamagata系毒株与B/Brisbane/3/2007的核苷酸同源性极高,在99.4%~99.7%之间;Victoria系乙型流感病毒株与B/Malasia/2506/2004的核苷酸同源性亦很高,在98.6%~99.1%之间。与疫苗株和其它流行株相比,本次分离的两个谱系毒株均未发现核苷酸的丢失和插入,但均增加一个潜在的糖基化位点。结论珠海市人群交替流行着Yamagata系和Victoria系两个抗原性不同的进化系的乙型流感病毒,病毒的基因发生了变异。2007-2008两年WHO推荐的乙型流感疫苗株与我地区当年流行株为不同谱系毒株,预防保护效果不好。     

2012年邯郸市乙型Yamagata系流感病毒HA1基因变异分析

目的研究邯郸市2012年流感监测中分离的Yamagata系乙型流感毒株HA1的抗原性和基因特性,阐明HA1基因的变异与流感流行的关系。方法用MDCK细胞分离培养流感病毒,提取病毒核酸,采用RT-PCR方法特异性扩增病毒HA1基因,进行核苷酸序列测定,用DNAStar中Megalign软件进行分析。结果2012年分离的Yamagata系乙型流感病毒与2008~2009年代表株B/Florida/4/2006相比亲缘关系较远,核苷酸同源性为96.2%~96.8%,氨基酸同源性为96.5%~97.4%,HA1区9个位点氨基酸发生替换,其中6个参与抗原表位构成;与WHO推荐的2012~2013年疫苗株B/Wisconsin/01/2010相比亲缘关系近,核苷酸同源性为98.8%~99.4%,氨基酸同源性为97.4%~98.5%,有5个位点发生氨基酸替换,其中3个参与抗原表位的构成;与国家流感中心提供的标准抗血清的血凝抑制滴度≥1︰640。结论邯郸市2012年分离的Yamagata系乙型流感病毒血凝素蛋白HA1与B/Florida/4/2006相比已形成新的变种,与B/Wisconsin/01/2010相比也发生了新的变异,但尚不能确定是否形成Yamagata系有代表性的新变种。     

Epidemiology of seasonal influenza in the Middle East and North Africa regions, 2010‐2016: Circulating influenza A and B viruses and spatial timing of epidemics

Background

There is a limited knowledge regarding the epidemiology of influenza in Middle East and North Africa.

Objectives

We described the patterns of influenza circulation and the timing of seasonal epidemics in countries of Middle East and North Africa.

Methods

We used virological surveillance data for 2010‐2016 from the WHO FluNet database. In each country, we calculated the median proportion of cases that were caused by each virus type and subtype; determined the timing and amplitude of the primary and secondary peaks; and used linear regression models to test for spatial trends in the timing of epidemics.

Results

We included 70 532 influenza cases from seventeen countries. Influenza A and B accounted for a median 76.5% and 23.5% of cases in a season and were the dominant type in 86.8% and 13.2% of seasons. The proportion of influenza A cases that were subtyped was 85.9%, while only 4.4% of influenza B cases were characterized. For most countries, influenza seasonality was similar to the Northern Hemisphere, with a single large peak between January and March; exceptions were the countries in the Arabian Peninsula and Jordan, all of which showed clear secondary peaks, and some countries had an earlier primary peak (in November‐December in Bahrain and Qatar). The direction of the timing of influenza activity was east to west and south to north in 2012‐2013 and 2015‐2016, and west to east in 2014‐2015.

Conclusions

The epidemiology of influenza is generally uniform in countries of Middle East and North Africa, with influenza B playing an important role in the seasonal disease burden.     

内蒙古自治区2015-2018年B Yamagata系流感病毒全基因组序列分析

目的 了解2015-2018年内蒙古自治区B Yamagata系流感病毒的全基因组序列特征。方法 采集流感样病例呼吸道标本进行流感病毒分离,提取病毒RNA,采用一步法RT-PCR扩增病毒全基因组序列并测序,通过生物信息学软件分析病毒基因特征。结果 本次研究的B Yamagata系流感病毒全基因与B/Phuket/3073/2013疫苗株的核苷酸同源性在97.7%~99.9%之间;B/Inner Mongolia/1200/2015和B/Inner Mongolia/1178/2015毒株发生抗原漂移,并出现HA-BY/NA-BV系间重配现象;所有毒株对神经氨酸酶抑制剂敏感。结论 2015-2018年内蒙古自治区B Yamagata系流感病毒抗原性和基因特征在逐渐发生变异,出现系间重配株,部分流感流行株与疫苗匹配性不佳。     

Molecular genetic characteristics of influenza A virus clinically isolated during 2011‐2016 influenza seasons in Korea

Background

The influenza virus is reportedly associated with 3‐5 million cases of severe illness and 250 000‐500 000 deaths annually worldwide.

Objectives

We investigated the variation of influenza A virus in Korea and examined the association with death.

Methods

A total of 13 620 cases were enrolled in the Hospital‐based Influenza Morbidity & Mortality surveillance system in Korea during 2011‐2016. Among these cases, a total of 4725 were diagnosed with influenza using RT‐PCR (influenza A; n = 3696, influenza B; n = 928, co‐infection; n = 101). We used 254 viral sequences from the 3696 influenza A cases for phylogenetic analysis using the BioEdit and MEGA 6.06 programs.

Results

We found that the sequences of A/H3N2 in the 2011‐2012 season belong to subgroup 3C.1, whereas the sequences in the 2012‐2013 season pertain to subgroup 3C.2. The sequences in the 2013‐2014 and 2014‐2015 seasons involve subgroups 3C.3a and 3C.2a. The A/H1N1pdm09 subtype belongs to subgroup 6 and contains two clusters. In addition, sequence analysis confirmed the several substitutions of internal genes and gene substitutions associated with drug resistance (I222V in NA and S31N in M2) in the fatal cases. While statistical analysis found no significant associations between genetic differences in the viruses and mortality, mortality was associated with certain host factors, such as chronic lung disease.

Conclusions

In conclusion, influenza A virus clade changes occurred in Korea during the 2011‐2016 seasons. These data, along with antigenic analysis, can aid in selecting effective vaccine strains. We confirmed that fatality in influenza A cases was related to underlying patient diseases, such as chronic lung disease, and further studies are needed to confirm associations between mortality and viral genetic substitutions.     

Evidence for an increase in the intensity of inter‐seasonal influenza,Queensland, Australia, 2009‐2019

BackgroundInter‐seasonal influenza cases have been increasing in Australia. Studies of influenza seasonality typically focus on seasonal transmission in temperate regions, leaving our understanding of inter‐seasonal epidemiology limited. We aimed to improve understanding of influenza epidemiology during inter‐seasonal periods across climate zones, and explored influenza intensity and strain dominance patterns over time.MethodsQueensland state‐wide laboratory‐confirmed influenza notifications and public laboratory influenza test data from 2009‐2019 were described by demographics, time period, region and strain type. We compared influenza intensity over time using the WHO Average Curve method to provide thresholds for seasonal and inter‐seasonal periods.ResultsAmong the 243 830 influenza notifications and 490 772 laboratory tests reported in Queensland between 2009 and 2019, 15% of notifications and 40% of tests occurred during inter‐seasonal periods, with 6.3% of inter‐seasonal tests positive. Inter‐seasonal notifications and tests substantially increased over time and increases in weekly proportions positive and intensity classifications suggested gradual increases in virus activity. Tropical inter‐seasonal activity was higher with periods of marked increase. Influenza A was dominant, although influenza B represented up to 72% and 42% of notifications during some seasonal and inter‐seasonal periods, respectively.ConclusionsUsing notification and testing data, we have demonstrated a gradual increase in inter‐seasonal influenza over time. Our findings suggest this increase results from an interplay between testing, activity and intensity, and strain circulation. Seasonal intensity and strain circulation appeared to modify subsequent period intensity. Routine year‐round surveillance data would provide a better understanding of influenza epidemiology during this infrequently studied inter‐seasonal time period.     

Epidemiology and molecular characterization of influenza viruses in Burkina Faso,sub‐Saharan Africa

Background

The importance of influenza viruses in respiratory infections in sub‐Saharan Africa has been historically overlooked, including in Burkina Faso.

Objectives

This study therefore aimed at evaluating the prevalence and seasonal occurrence of influenza viruses in children under 5 years old, at risk of influenza‐related complications, presenting with influenza‐like illness (ILI) or severe acute respiratory infection (SARI). The study also aimed at identifying the periods with increased influenza transmission for vaccination recommendations in Burkina Faso.

Methods

From January 2014 to December 2015, ILI and SARI (2015 only) patients were recruited in six healthcare centers in Burkina Faso. Influenza A and B molecular detection and subtyping were performed. Clade clustering of a subset of A(H1N1)pdm09 and A(H3N2) strains was deduced by performing phylogenetic analyses on hemagglutinin gene sequences. Weekly surveillance data from FluNet (2011‐2013; 2016) and this study (2014‐2015) were used to identify periods of increased influenza activity.

Results

Influenza A and B viruses were detected in 15.1% (112 of 743) of ILI and 6.6% (12 of 181) of SARI patients. Overall, influenza A viruses were largely predominant (81 of 124, 65.3%), with 69.1% of A(H3N2) and 30.9% of A(H1N1)pdm09 strains. Four waves of increased transmission were identified in 2014‐2015, each dominated by different influenza subtypes and clades. Between 2011 and 2016, periods of increased influenza activity varied in their frequency, duration, and timing.

Conclusion

Influenza A and B viruses were detected in a substantial number of ILI and SARI cases in Burkina Faso. Vaccination in September‐October would likely protect the highest number of patients.     

Hospitalization following outpatient medical care for influenza: US influenza vaccine effectiveness network, 2011‐12—2015‐16

Over five seasons, we determined the proportion of outpatients with laboratory‐confirmed, influenza‐associated illness who were hospitalized within 30 days following the outpatient visit. Overall, 136 (1.7%) of 7813 influenza‐positive patients were hospitalized a median of 4 days after an outpatient visit. Patients aged ≥ 65 years and those with high‐risk conditions were at increased risk of hospitalization. After controlling for age and high‐risk conditions, vaccination status and infecting influenza virus type were not associated with hospitalization risk among adults.     

Epidemiology and outcomes of acute liver failure in Australia

BACKGROUND Acute liver failure(ALF) is a life-threatening syndrome with varying aetiologies requiring complex care and multidisciplinary management. Its changing incidence, aetiology and outcomes over the last 16 years in the Australian context remain uncertain.AIM To describe the changing incidence, aetiology and outcomes of ALF in South Eastern Australia.METHODS The database of the Victorian Liver Transplant Unit was interrogated to identify all cases of ALF in adults( 16 years) in adults hospitalised between January 2002 and December 2017. Overall, 169 patients meeting criteria for ALF were identified. Demographics, aetiology of ALF, rates of transplantation and outcomes were collected for all patients. Transplant free survival and overall survival(OS) were assessed based on survival to discharge from hospital. Results were compared to data from a historical cohort from the same unit from 1988-2001.RESULTS Paracetamol was the most common aetiology of acute liver failure, accounting for50% of cases, with an increased incidence compared with the historical cohort(P= 0.046). Viral hepatitis and non-paracetamol drug or toxin induced liver injury accounted for 15% and 10% of cases respectively. Transplant free survival(TFS)improved significantly compared to the historical cohort(52% vs 38%, P = 0.032).TFS was highest in paracetamol toxicity with spontaneous recovery in 72% of cases compared to 31% of non-paracetamol ALF(P 0.001). Fifty-nine patients were waitlisted for emergency liver transplantation. Nine of these died while waiting for an organ to become available. Forty-two patients(25%) underwent emergency liver transplantation with a 1, 3 and 5 year survival of 81%, 78% and72% respectively.CONCLUSION Paracetamol toxicity is the most common aetiology of ALF in South-Eastern Australia with a rising incidence over 30 years. TFS has improved, however it remains low in non-paracetamol ALF.     

Literature review of the epidemiology of influenza B disease in 15 countries in the Asia‐Pacific region

Influenza control strategies focus on the use of trivalent influenza vaccines containing two influenza A virus subtypes and one of the two circulating influenza type B lineages (Yamagata or Victoria). Mismatches between the vaccine B lineage and the circulating lineage have been regularly documented in many countries, including those in the Asia‐Pacific region. We conducted a literature review with the aim of understanding the relative circulation of influenza B viruses in Asia‐Pacific countries. PubMed and Western Pacific Region Index Medicus were searched for relevant articles on influenza type B published since 1990 in English language for 15 Asia‐Pacific countries. Gray literature was also accessed. From 4834 articles identified, 121 full‐text articles were analyzed. Influenza was reported as an important cause of morbidity in the Asia‐Pacific region, affecting all age groups. In all 15 countries, influenza B was identified and associated with between 0% and 92% of laboratory‐confirmed influenza cases in any one season/year. Influenza type B appeared to cause more illness in children aged between 1 and 10 years than in other age groups. Epidemiological data for the two circulating influenza type B lineages remain limited in several countries in the Asia‐Pacific, although the co‐circulation of both lineages was seen in countries where strain surveillance data were available. Mismatches between circulating B lineages and vaccine strains were observed in all countries with available data. The data suggest that a shift from trivalent to quadrivalent seasonal influenza vaccines could provide additional benefits by providing broader protection.     

Epidemiology and Molecular Analyses of Influenza B Viruses in Senegal from 2010 to 2019

Influenza virus types A and B are responsible for acute viral infections that affect annually 1 billion people, with 290,000 to 650,000 deaths worldwide. In this study, we investigated the circulation of influenza B viruses over a 10-year period (2010–2019). Specimens from patients suspected of influenza infection were collected. Influenza detection was performed following RNA extraction and real-time RT-PCR. Genes coding for hemagglutinin (HA) and neuraminidase (NA) of influenza B viruses were partially sequenced, and phylogenetic analyses were carried out subsequently. During the study period, we received and tested a total of 15,156 specimens. Influenza B virus was detected in 1322 (8.7%) specimens. The mean age of influenza B positive patients was 10.9 years. When compared to reference viruses, HA genes from Senegalese circulating viruses showed deletions in the HA1 region. Phylogenetic analysis highlighted the co-circulation of B/Victoria and B/Yamagata lineage viruses with reassortant viruses. We also noted a clear seasonal pattern of circulation of influenza B viruses in Senegal.