Pdm09 Virus Infection Research Articles

Duration of fever in children infected with influenza A(H1N1)pdm09, A(H3N2) or B virus and treated with baloxavir marboxil, oseltamivir, laninamivir, or zanamivir in Japan during the 2012–2013 and 2019–2020 influenza seasons

We compared the duration of fever in children infected with A(H1N1)pdm09, A(H3N2), or influenza B viruses following treatment with baloxavir marboxil (baloxavir) or neuraminidase inhibitors (NAIs) (oseltamivir, zanamivir, or laninamivir). This observational study was conducted at 10 outpatient clinics across 9 prefectures in Japan during the 2012–2013 and 2019–2020 influenza seasons. Patients with influenza rapid antigen test positive were treated with one of four anti-influenza drugs. The type/subtype of influenza viruses were identified from MDCK or MDCK SIAT1 cell-grown samples using two-step real-time PCR. Daily self-reported body temperature after treatment were used to evaluate the duration of fever by treatment group and various underlying factors. Among 1742 patients <19 years old analyzed, 452 (26.0%) were A(H1N1)pdm09, 827 (48.0%) A(H3N2), and 463 (26.0%) influenza B virus infections. Among fours treatment groups, baloxavir showed a shorter median duration of fever compared to oseltamivir in univariate analysis for A(H1N1)pdm09 virus infections (baloxavir, 22.0 h versus oseltamivir, 26.7 h, P < 0.05; laninamivir, 25.5 h, and zanamivir, 25.0 h). However, this difference was not significant in multivariable analyses. For A(H3N2) virus infections, there were no statistically significant differences observed (20.3, 21.0, 22.0, and 19.0 h) uni- and multivariable analyses. For influenza B, baloxavir shortened the fever duration by approximately 15 h than NAIs (20.3, 35.0, 34.3, and 34.1 h), as supported by uni- and multivariable analyses. Baloxavir seems to have comparable clinical effectiveness with NAIs on influenza A but can be more effective for treating pediatric influenza B virus infections than NAIs.

Influenza A (H1N1) Virus Outbreak in the Districts of Chhattisgarh: A Cross-Sectional Study.

Background The H1N1 flu is a subtype of the influenza A virus, also known as the swine flu. An entirely new strain of the H1N1 virus started sickening people in the 2009-2010 flu season. It was a novel influenza virus combination that can infect humans, pigs, and birds. It was frequently referred to as the "swine flu."The virus may be able to spread for a little while longer in children and individuals with compromised immune systems. Objective The objective is to investigate the outbreaks of H1N1 among young adults in the Bastar District of Chhattisgarh. Methods Collection of the blood samples of 342 individuals between December 2015 and November 2017 was done. Thirty-one cases of Influenza A (H1N1) PDM09 virus infection were identified and confirmed. The molecular relationship between viruses is identified by the real-time polymerase chain reaction (RT-PCR) method. Result The majority of samples (n=13) were sourced from Raipur Medical College, followed by contributions from Durg District Hospital (n=5), Raigarh Medical College (n=4), Rajnandgaon District Hospital (n=3), Jagdalpur Medical College (n=2), Bilaspur Medical College (n=2), and smaller contributions from Dhamtari District Hospital and Gariyabandh Primary Health Care. Among these, 31 samples tested positive for Influenza A (H1N1) PDM 2009 virus, with a slightly higher prevalence among 19 female patients. Age-wise distribution revealed higher proportions of positive cases in the age groups of 0-10 years, 31-40 years, and 21-30 years. In the molecular analysis, 154 samples showed no target amplification, while 125 samples exhibited amplification of only Influenza A without subtype (H1) amplification. Remarkably, 31 patients who tested positive for Influenza A (H1N1) died from the virus; most of the deaths were in children under five and middle-aged adults. Conclusion The detection of Influenza A (H1N1) PDM 2009 virus, especially among females, indicates its persistent circulation. Positive cases were prevalent among younger and middle-aged individuals. Molecular analysis showed subtype variations, with significant fatalities observed in children under five and middle-aged adults, emphasizing the severity of the virus across different age groups. It is advised that in order to keep Indian influenza surveillance up to date and robust, more epidemiological data should be gathered, along with information on risk factors like immunization status, hospitalization, and mortality rates should be estimated, and influenza case subtyping should be improved.

Epidemiological investigation of lower respiratory tract infections during influenza A (H1N1) pdm09 virus pandemic based on targeted next-generation sequencing.

Co-infection has been a significant contributor to morbidity and mortality in previous influenza pandemics. However, the current influenza A (H1N1) pdm09 virus pandemic, as the first major outbreak following the SARS-CoV-2 pandemic, may differ epidemiologically. Further investigation is necessary to understand the specific features and impact of this influenza A pandemic. Study design: We conducted a retrospective cohort study at a Chinese hospital between January and April 2023, focusing on patients with lower respiratory tract infections. Pathogen detection employed targeted next-generation sequencing (tNGS) on bronchoalveolar lavage fluid (BALF) or sputum samples. This study enrolled 167 patients with lower respiratory tract infections, and the overall positivity rate detected through tNGS was around 80%. Among them, 40 patients had influenza A (H1N1) pdm09 virus infection, peaking in March. In these patients, 27.5% had sole infections, and 72.5% had co-infections, commonly with bacteria. The frequently detected pathogens were Aspergillus fumigatus, SARS-CoV-2, and Streptococcus pneumoniae. For non-influenza A virus-infected patients, the co-infection rate was 36.1%, with 42.3% having SARS-CoV-2. Patients with influenza A virus infection were younger, had more females and diabetes cases. Among them, those with sole infections were older, with less fever and asthma but more smoking history. Regarding prognosis, compared to sole influenza A virus infection, co-infected patients demonstrated higher 21-day recovery rates and a higher incidence of heart failure. However, they exhibited lower proportions of respiratory failure, acute kidney failure, septic shock, and hospital stays lasting more than 10 days. Interestingly, patients with non-influenza A virus infection had a significantly lower 21-day recovery rate. Correlation analysis indicated that the 21-day recovery rate was only associated with influenza A (H1N1) pdm09 virus. During the current pandemic, the influenza A (H1N1) pdm09 virus may have been influenced by the SARS-CoV-2 pandemic and did not exhibit a strong pathogenicity. In fact, patients infected with influenza A virus showed better prognoses compared to those infected with other pathogens. Additionally, tNGS demonstrated excellent detection performance in this study and showed great potential, prompting clinical physicians to consider its use as an auxiliary diagnostic tool.

Burden of influenza A (H1N1)pdm09 infection among tuberculosis patients: a prospective cohort study

BackgroundInfluenza and tuberculosis both cause significant morbidity and mortality worldwide. Therefore, this study aimed to estimate the burden of influenza A (H1N1)pdm09 virus infection among human tuberculosis patients and the general population.MethodsA prospective cohort study was conducted among a cohort group (TB positive patients) as exposed and a comparison group (general population) as non-exposed. A total of 304 participants were recruited in both groups and followed for a period of 12 weeks. Of the 304 concurrently enrolled individuals, 152 were TB-positive patients (cohort group) and 152 were from the general population (comparison group).To calculate the sample size, the power of study was kept at 80% for detecting a difference at 5% alpha level assuming the 25% prevalence of respiratory viruses in cohort group compared to 12.5% in general population. An oropharyngeal swab was taken from a participant with symptoms of influenza-like illness (ILI). Samples were tested by conventional reverse transcription polymerase chain reaction (RT-PCR) for the detection of influenza A (H1N1)pdm09. All statistical analyses were conducted using R software.ResultsA total of 95 participants developed influenza-like illness (ILI) symptoms. Among these, 64 tested positive for influenza A(H1N1)pdm09, of which 39 were from the exposed group and 25 were from the non-exposed group. During the 12-week period of follow-up, the influenza A (H1N1)pdm09 incidence rate was 20 per 1000 people. The risk of testing positive for influenza A (H1N1)pdm09 was 1.66 times higher in the exposed group compared to the non-exposed group. The cumulative incidence indicated that 25% of the TB cohort and 16% of the comparison group were at risk of getting influenza A (H1N1)pdm09 during the 12 weeks of follow-up.ConclusionParticipants from the TB cohort had a higher incidence of influenza A (H1N1)pdm09 than the general population suggesting that they should be prioritized for influenza vaccination.

Serum 25-Hydroxyvitamin D Was Not Associated with Influenza Virus Infection in Children and Adults in Hong Kong, 2009–201

Background: Some studies have hypothesized that vitamin D may have a role to play in protection against influenza virus infections and illnesses, and that seasonal fluctuation in serum 25-hydroxyvitamin D [25(OH)D] may affect seasonal patterns of influenza virus infections.Objective: We aimed to investigate whether serum 25(OH)D concentrations were associated with the incidence of influenza virus infections and illnesses in children and adults in Hong Kong.Methods: In 2009–2010, 3030 children and adults of all ages from 796 households in Hong Kong were followed up to identify acute respiratory illnesses. Sera from 2694 participants were collected at baseline and after ∼1 mo, 6 mo, and 12 mo. Influenza virus infections were confirmed by reverse transcriptase–polymerase chain reaction performed on nasal and throat swab samples collected during illness episodes. Serologic evidence of influenza virus infection was measured by hemagglutination inhibition assays in unvaccinated participants. The serum 25(OH)D concentrations were measured after collection of all specimens. Each individual’s baseline serum 25(OH)D concentration on 1 January 2010 was predicted by a random-effects linear regression model.Results: We found that, in children and adults who had not received a seasonal influenza vaccine, baseline serum 25(OH)D concentrations (<50 nmol/L compared with ≥50 nmol/L) were not statistically significantly associated with serologic evidence of influenza A(H1N1)pdm09 (RR, 1.18; 95% CI: 0.85, 1.65) or seasonal influenza virus infections [including A(H3N2) and B virus] (RR, 1.13; 95% CI: 0.86, 1.49). In all participants, baseline serum 25(OH)D concentrations were not statistically significantly associated with polymerase chain reaction–confirmed influenza virus infection (RR, 1.15; 95% CI: 0.73, 1.83) and influenza-like illness (RR, 1.18; 95% CI: 0.98, 1.43).Conclusions: These findings indicate that lower serum vitamin D concentrations may not contribute to the seasonality of influenza and are not associated with an increased risk of influenza virus infections in persons of all ages in Hong Kong.

Evaluation of panel of neutralising murine monoclonal antibodies and a humanised bispecific antibody against influenza A(H1N1)pdm09 virus infection in a mouse model

The influenza A (H1N1) pdm09 virus attracted public attention because of its high prevalence. The annual global morbidity and mortality rates of influenza remain high despite the application of influenza vaccines and antiviral drugs, which indicates the urgent need to identify a more effective strategy for controlling and treating A(H1N1) pdm09 influenza infection. To produce a highly effective therapeutic with broad specificity for A(H1N1) pdm09 influenza viruses, we generated 15 murine monoclonal antibodies (mAbs) via hybridoma technology: 11 mAbs demonstrated 20–100% therapeutic protection in a mouse model of A(H1N1) pdm09 infection at a single dose of 10 mg/kg. A humanised bispecific antibody (Bis-Hu11-1) generated based on the mAbs 3D2 and 3D11, combining the specificities of the two mAbs, was also effective in preventing and treating A(H1N1) pdm09 infection in a mouse model. Bis-Hu11-1 demonstrated hemagglutination inhibition (HI) activity against the escape mutants generated by its parental mAbs that resulted in the obvious reduction in the HI activity of the parental mAbs. In summary, we generated a panel of neutralising mAbs against A(H1N1) pdm09 influenza virus. This study presents a promising method for developing neutralising antibodies that potentially target a series of antigenically diverse influenza viruses.

Low quality antibody responses in critically ill patients hospitalized with pandemic influenza A(H1N1)pdm09 virus infection

Although some adults infected with influenza 2009 A(H1N1)pdm09 viruses mounted high hemagglutination inhibition (HAI) antibody response, they still suffered from severe disease, or even death. Here, we analyzed antibody profiles in patients (n = 31, 17–65 years) admitted to intensive care units (ICUs) with lung failure and invasive mechanical ventilation use due to infection with A(H1N1)pdm09 viruses during 2009–2011. We performed a comprehensive analysis of the quality and quantity of antibody responses using HAI, virus neutralization, biolayer interferometry, enzyme-linked-lectin and enzyme-linked immunosorbent assays. At time of the ICU admission, 45% (14/31) of the patients had HAI antibody titers ≥ 80 in the first serum (S1), most (13/14) exhibited narrowly-focused HAI and/or anti-HA-head binding antibodies targeting single epitopes in or around the receptor binding site. In contrast, 42% (13/31) of the patients with HAI titers ≤ 10 in S1 had non-neutralizing anti-HA-stem antibodies against A(H1N1)pdm09 viruses. Only 19% (6/31) of the patients showed HA-specific IgG1-dominant antibody responses. Three of 5 fatal patients possessed highly focused cross-type HAI antibodies targeting the (K130 + Q223)-epitopes with extremely low avidity. Our findings suggest that narrowly-focused low-quality antibody responses targeting specific HA-epitopes may have contributed to severe infection of the lower respiratory tract.

Clinical Profile of Pneumonia and Its Association with Rain Wetting in Patients Admitted at a Tertiary Care Institute During Pandemic of Influenza A (H1N1) pdm09 Virus Infection

Influenza pneumonia often occurs as epidemics in the Asian countries and have significant impact on the health of world population. We studied the association of rain-wetting with occurrence of pneumonia during the outbreak of the influenza A (H1N1) pdm09 virus infection. All patients admitted with community-acquired pneumonia during the period 13th September to 10th October 2010 were recruited in the present study. The diagnosis of influenza was established by real-time polymerase chain reaction (RT-PCR). The demographic data and clinical profile of the patients were recorded with a special consideration to record of possible risk factors. Of the 123 patients studied, 39 (32%) patients had tested positive for influenza A (H1N1) pdm09; 12 (10%) tested positive for influenza A and remaining 72 (58%) patients were negative for influenza virus. Pattern of illness was almost identical in H1N1-positive and-negative groups. History of rain-wetting was present in 48 patients (39%) preceding the onset of illness. Getting wet in the rain was significantly higher in patients with pneumonia than control subjects [odds ratio 2.53, 95% confidence intervals (CI) 1.301-4.91; p=0.009)]. The number of pneumonia patients was also higher on rainy days and the numbers started declining a week later. More pneumonia patients are admitted during the periods of greater rainfall and rain-wetting may be an important risk factor for the occurrence of pneumonia.

Clinical Profile of Pneumonia and Its Association with Rain Wetting in Patients Admitted at a Tertiary Care Institute During Pandemic of Influenza A (H1N1) pdm09 Virus Infection

Clinical Profile of Pneumonia and Its Association with Rain Wetting in Patients Admitted at a Tertiary Care Institute During Pandemic of Influenza A (H1N1) pdm09 Virus Infection

The effect of influenza A (H1N1) pdm09 virus infection on cytokine production and gene expression in BV2 microglial cells

Acute influenza infection has been reported to be associated with neurological symptoms such as influenza-associated encephalopathy (IAE). Although the pathophysiology of this condition remain unclear, neuroinflammation and associated alterations in the central nervous system (CNS) are usually induced. Microglia (MGs), CNS-resident macrophages, are generally the first cells to be activated in response to brain infection or damage. We performed reverse transcriptase droplet digital PCR (RT-ddPCR) and luminex assays to investigate virus proliferation and immune reactions in BV2 MGs infected with influenza A(H1N1)pdm09 virus. Furthermore, isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics methods were used to investigate the dynamic change in the protein expression profile in BV2 MGs to gain insight into the CNS response to influenza A (H1N1) pdm09 infection. Our results showed that the influenza A(H1N1)pdm09 virus was replicative and productive in BV2 MG cells, which produced cytokines such as interleukin (IL)-1β, IL-6, tumour necrosis factor (TNF)-α and monocyte chemoattractant protein (MCP)-1. The expression of osteopontin (OPN) in the influenza A (H1N1) pdm09-infected BV2 MGs was upregulated at 16 and 32 h post-infection (hpi) compared to that in the control group, resulting in aggravated brain damage and inflammation. Our study indicates that OPN signalling might provide new insights into the treatment of CNS injury and neurodegenerative diseases in IAE.

TNFA and IL10 Polymorphisms and IL-6 and IL-10 Levels Influence Disease Severity in Influenza A(H1N1)pdm09 Virus Infected Patients

Cytokines are key modulators of immune response, and dysregulated production of proinflammatory and anti-inflammatory cytokines contributes to the pathogenesis of influenza A(H1N1)pdm09 virus infection. Cytokine production is impacted by single nucleotide polymorphisms (SNPs) in the genes coding for them. In the present study, SNPs in the IL6, TNFA, IFNG, IL17A, IL10, and TGFB were investigated for their association with disease severity and fatality in influenza A(H1N1)pdm09-affected patients with mild disease (n = 293) and severe disease (n = 86). Among those with severe disease, 41 patients had fatal outcomes. In a subset of the patients, levels of IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, and IL-17 were assayed in the plasma for their association with severe disease. The frequency of TNFA rs1800629 G/A allele was significantly higher in severe cases and survived severe cases group compared to that of those with mild infection (OR with 95% for mild vs. severe cases 2.95 (1.52–5.73); mild vs. survived severe cases 4.02 (1.84–8.82)). IL10 rs1800896-rs1800872 G-C haplotype was significantly lower (OR with 95% 0.34 (0.12–0.95)), while IL10 rs1800896-rs1800872 G-A haplotype was significantly higher (OR with 95% 12.11 (2.23–76.96)) in fatal cases group compared to that of the mild group. IL-6 and IL-10 levels were significantly higher in fatal cases compared to that of survived severe cases. IL-6 levels had greater discriminatory power than IL-10 to predict progression to fatal outcome in influenza A(H1N1)pdm09 virus-infected patients. To conclude, the present study reports the association of TNFA and IL10 SNPs with severe disease in Influenza A(H1N1)pdm09 virus-infected subjects. Furthermore, IL-6 levels can be a potential biomarker for predicting fatal outcomes in Influenza A(H1N1)pdm09 virus infected subjects.

Hemolytic Uremic Syndrome Following Influenza A (H1N1) pdm09 Virus in a 14-Month-Old Girl:

Hemolytic Uremic Syndrome (HUS) is characterized by the clinical triad of microangiopathic non-immune hemolytic anemia, thrombocytopenia, and acute renal failure. There are infections, genetic causes, malignancies, autoimmune diseases, drugs, and many unexplained causes in the etiology of HUS. The most common cause of HUS in children is Shiga toxin-producing Escherichia coli (STEC). In the literature, few influenza A (H1N1) pdm09 virus-related HUS cases are reported. In this case report, a case with hemolytic uremic syndrome associated with influenza A (H1N1) pdm09 virus infection is presented.

Longitudinal Projection of Herd Prevalence of Influenza A(H1N1)pdm09 Virus Infection in the Norwegian Pig Population by Discrete-Time Markov Chain Modelling

In order to quantify projections of disease burden and to prioritise disease control strategies in the animal population, good mathematical modelling of infectious disease dynamics is required. This article investigates the suitability of discrete-time Markov chain (DTMC) as one such model for forecasting disease burden in the Norwegian pig population after the incursion of influenza A(H1N1)pdm09 virus (H1N1pdm09) in Norwegian pigs in 2009. By the year-end, Norway’s active surveillance further detected 20 positive herds from 54 random pig herds, giving an estimated initial population prevalence of 37% (95% CI 25–52). Since then, Norway’s yearly surveillance of pig herd prevalence has given this study 11 years of data from 2009 to 2020 to work with. Longitudinally, the pig herd prevalence for H1N1pdm09 rose sharply to >40% in three years and then fluctuated narrowly between 48% and 49% for 6 years before declining. This initial longitudinal pattern in herd prevalence from 2009 to 2016 inspired this study to of test the steady-state discrete-time Markov chain model in forecasting disease prevalence. With the pig herd as the unit of analysis, the parameters for DTMC came from the initial two years of surveillance data after the outbreak, namely vector prevalence, first herd incidence and recovery rates. The latter two probabilities formed the fixed probability transition matrix for use in a discrete-time Markov chain (DTMC) that is quite similar to another compartmental model, the susceptible–infected–susceptible (SIS) model. These DTMC of predicted prevalence (DTMCP) showed good congruence (Pearson correlation = 0.88) with the subsequently observed herd prevalence for seven years from 2010 to 2016. While the DTMCP converged to the stationary (endemic) state of 48% in 2012, after three time steps, the observed prevalence declined instead from 48% after 2016 to 25% in 2018 before rising to 29% in 2020. A sudden plunge in H1N1pdm09 prevalence amongst Norwegians during the 2016/2017 human flu season may have had a knock-on effect in reducing the force of infection in pig herds in Norway. This paper endeavours to present the discrete-time Markov chain (DTMC) as a feasible but limited tool in forecasting the sequence of a predicted infectious disease’s prevalence after it’s incursion as an exotic disease.

Modulation of endothelial factors activity in human endothelial cells in influenza A(H1N1)pdm09 virus infection

Influenza A virus infection can lead to endothelial dysfunction (ED), including apoptosis of endothelial cells and modulation of endothelial factor activities. Affected biochemical factors may include those playing important roles in vascular homeostasis. However, the effect of this pathogen on the expression pattern of key endothelial factors is still unknown.The aim of this work was to study the expression of endothelial nitric oxide synthase (eNOS) and plasminogen activator inhibitor-1 (PAI-1, serpin E1) in the EA.hy926 endothelial cells. to assess expression of eNOS and PAI-1 in endothelial cells infected with influenza virus A(H1N1)pdm09, and to identify homologous fragments in structure of viral proteins and endothelial factors. Cells were infected with influenza virus A/St. Petersburg/48/16 (H1N1)pdm09 and analyzed in dynamics in 6, 12, 18, 24, 48, and 72 hrs post infection (hpi). Detection of endothelial factors expression levels was performed by immunocytochemical method (ICC) using antibodies for eNOS and PAI-1 while quantitative assessment of expression levels was carried out by program Nis-Elements F3.2 («Nikon», Japan). The search for homologous sequences between viral proteins and eNOS and PAI-1 was performed by computer comparison. Sequences were analyzed as fragments 12 amino acid residues (aar) in length. eNOS expression in infected cells had decreased to 7.9% by 6 hpi (control was taken as 100%) to 3.3% at 72 hpi. PAI-1 expression varied significantly over the course of the experiment: by 6 hpi it had decreased to 49.6%, and to 43.2% by 12 hpi. Later PAI-1 levels were: 116.3% (18 hpi); 18.9% (24 hpi); 23.5% (48 hpi), and 35% (72 hpi). These results indicate that influenza A infection of endothelial cells causes a significant decrease in eNOS expression, while modulating PAI-1 one. The described phenomenon can be used in the further development of directions of pathogenetic therapy of vascular complications of infection caused by this pathogen.

Cluster of Oseltamivir-Resistant and Hemagglutinin Antigenically Drifted Influenza A(H1N1)pdm09 Viruses, Texas, USA, January 2020.

Four cases of oseltamivir-resistant influenza A(H1N1)pdm09 virus infection were detected among inhabitants of a border detention center in Texas, USA. Hemagglutinin of these viruses belongs to 6B.1A5A-156K subclade, which may enable viral escape from preexisting immunity. Our finding highlights the necessity to monitor both drug resistance and antigenic drift of circulating viruses.

Eosinophil Extracellular Traps in the Casts of Plastic Bronchitis Associated With Influenza Virus Infection

Plastic bronchitis (PB) is a rare pulmonary disease characterized by production of cohesive and branching casts that fill the airway. 1 Rubin B.K. Plastic bronchitis. Clin Chest Med. 2016; 37: 405-408 Abstract Full Text Full Text PDF PubMed Scopus (42) Google Scholar PB is classified into two types based on differences in the mechanism of development. Lymphatic PB, sometimes called “classic,” is associated mainly with congenital heart diseases or lymphatic anomalies, in the development of which aberrant pulmonary lymphatics appear to play a major role. Nonlymphatic PB is associated mainly with respiratory diseases, in which inflammatory immune cells may play a role. We and others have reported that influenza A (H1N1) pdm09 virus infection causes PB, especially in patients with an allergy and/or asthma. 2 Uda K. Shoji K. Koyama-Wakai C. et al. Clinical characteristics of influenza virus-induced lower respiratory infection during the 2015 to 2016 season. J Infect Chemother. 2018; 24: 407-413 Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar ,3 Uchimura T. Mori M. Nariai A. Yokota S. Analysis of cases of severe respiratory failure in children with influenza (H1N1) 2009 infection in Japan. J Infect Chemother. 2012; 18: 59-65 Abstract Full Text PDF PubMed Scopus (10) Google Scholar Casts from some patients with PB due to influenza virus infection (Flu-PB) were composed of fibrin and such inflammatory immune cells as eosinophils and neutrophils. 4 Deng J. Zheng Y. Li C. Ma Z. Wang H. Rubin B.K. Plastic bronchitis in three children associated with 2009 influenza A(H1N1) virus infection. Chest. 2010; 138: 1486-1488 Abstract Full Text Full Text PDF PubMed Scopus (36) Google Scholar These findings indicate that granulocytes, as well as an allergic status, are likely to be involved in the pathophysiologic condition of Flu-PB. However, the detailed mechanisms of how highly viscous casts are formed in patients with Flu-PB and the roles of granulocytes remain unclear.

Changes in characteristics and case-severity in patients hospitalised with influenza A (H1N1) pdm09 infection between two epidemic waves-England, 2009-2010.

BackgroundDuring 2009‐2010, pandemic influenza A (H1N1) pdm09 virus (pH1N1) infections in England occurred in two epidemic waves. Reasons for a reported increase in case‐severity during the second wave are unclear.MethodsWe analysed hospital‐based surveillance for patients with pH1N1 infections in England during 2009‐2010 and linked national data sets to estimate ethnicity, socio‐economic status and death within 28 days of admission. We used multivariable logistic regression to assess whether changes in demographic, clinical and management characteristics of patients could explain an increase in ICU admission or death, and accounted for missing values using multiple imputation.ResultsDuring the first wave, 54/960 (6%) hospitalised patients required intensive care and 21/960 (2%) died; during the second wave 143/1420 (10%) required intensive care and 55/1420 (4%) died. In a multivariable model, during the second wave patients were less likely to be from an ethnic minority (OR 0.33, 95% CI 0.26‐0.42), have an elevated deprivation score (OR 0.75, 95% CI 0.68‐0.83), have known comorbidity (OR 0.78, 95% CI 0.63‐0.97) or receive antiviral therapy ≤2 days before onset (OR 0.72, 95% CI 0.56‐0.92). Increased case‐severity during the second wave was not explained by changes in demographic, clinical or management characteristics.ConclusionsMonitoring changes in patient characteristics could help target interventions during multiple waves of COVID‐19 or a future influenza pandemic. To understand and respond to changes in case‐severity, surveillance is needed that includes additional factors such as admission thresholds and seasonal coinfections.

A cluster epidemic of influenza A(H1N1)pdm09 virus infection in four captive cheetahs (Acinonyx jubatus)

In January 2019, four cheetahs (Acinonyx jubatus) kept at a Japanese zoo intermittently showed respiratory signs following the incidence of seasonal influenza in animal caregivers. Respiratory materials (saliva, sputum and food tray swabs) were non-invasively collected from the four cheetahs. Although we were unable to isolate the virus, the NP gene of influenza A virus was detected in three of the cheetahs but not in the fourth cheetah that had nearly recovered. From a food tray swab which tested weakly positive by a commercial influenza detection kit, we were able to obtain the whole-genome sequence of the influenza A virus. Analysis of the genome, A/cheetah/Kanagawa/2/2019(H1N1), revealed that the virus was closely related to influenza A(H1N1)pdm09 viruses isolated from humans in Japan in the 2018-2019 winter. Production of haemagglutinin inhibition (HI) antibodies (64-128 HI) against an A(H1N1)pdm09 virus in plasma samples confirmed infection of all four cheetahs. The animals continued to produce antibodies for at least 314days after disease onset. These findings strongly suggest that reverse zoonotic transmission of A(H1N1)pdm09 virus occurred from human to cheetah and subsequently from cheetah to cheetah in the zoo. We also show that specimens can be safely and non-invasively collected from non-domesticated animals and used to investigate respiratory infectious diseases.

Evaluation of Pregnancy, Younger Age, and Old Age as Independent Risk Factors for Poor Hospitalization Outcomes in Influenza A (H1N1)pdm09 Virus a Decade After the Pandemic.

IntroductionThe influenza A (H1N1)pdm09 virus infection was first reported in Mexico in 2009 and quickly became the first flu pandemic of the 21st century. Statistics show that the prevalence of H1N1 infection was higher among young adults during the pandemic while the elderly were at more risk of death. However; many studies have shown a gradual change over the years, with attack rates increasing in older adults as compared to young adults. The other significant vulnerable group for this infection seems to be pregnant women. Over the years, many authors have found that pregnancy may not be a significant risk factor for increased hospitalization and poorer outcomes. This study aims to perform a comparative analysis and thereby assess pregnancy, younger age, and old age as independent risk factors for poor hospitalization outcomes.Materials and methodsThe hospital records of all patients with H1N1 infection admitted between January 1, 2018, to December 31, 2018, were screened. The patients included in the study were young adults (18-31 years), pregnant women, and the elderly (≥65 years). Comparative analysis was done between them. Nominal variables were compared using the chi-square test.ResultsA total of 379 patients were admitted to our hospital with H1N1 infection from January 1, 2018, to December 31, 2018. There were 75 elderly (19.7%), 224 (59%) middle-aged adults, 55 (14.5%) young adults, and 25 (6.5%) pregnant women. Fever (90%, 84%, and 96%) and cough with expectoration (72%, 67.3%, and 40%) were the most prevalent symptoms. The elderly reported more dyspnoea (28% vs. 5.5%, 4 %). Diabetes mellitus was found in 73.3 % of the elderly, 3.6% of the young adults, and 12% of pregnant women. Hypertension was present in 45% of the elderly, 1.8% of young adults, and 4% of pregnant women. Coronary artery disease was seen in 22.7% of the elderly and 1.8% of young adults. Chronic kidney disease (5.3%) and chronic obstructive pulmonary disease (13.3%) were seen only in the elderly group. Relative lymphopenia was prevalent in all groups and was more in pregnant women (76% vs. 61.8% and 41.8%) as compared to other groups. Serum creatinine was elevated in 38% of the elderly, 2% of young adults, and 0% of pregnant women. Abnormal chest radiograph was reported for 48% of the elderly, 30.9% of young adults, and 12% of pregnant women. Twenty-six point seven percent (26.7%) of the elderly needed more than a weeks' stay as compared to 7.3% of young adults and 20% of pregnant women. Thirty-two percent (32%) of the elderly required intensive care as compared to 1.5% of young adults and none of the pregnant women. More of the elderly (26.7%) required ventilator support than other groups (7.3% and 4%). About 25.3% of the elderly had a superinfection. Eight percent (8%) of the elderly died in the study while none died in the other groups.ConclusionAge representation and poor hospitalization outcomes due to H1N1 seem to have shifted from young adults to older age groups. The elderly are at more risk for a prolonged stay, intensive care, ventilator support, and death as compared to young adults and pregnant women. Pregnancy may not be associated with poor hospitalization outcomes for H1N1 as has been earlier thought.

Meta-analysis on association between TNF-α and CCR5Δ32 gene polymorphisms and influenza A(H1N1)pdm09

Objective: To investigate the associations between TNF-α and CCR5Δ32 gene polymorphisms and influenza A(H1N1)pdm09. Methods: Studies in PubMed, Cochrane Library, OVID, EBSCO, Web of Science published before February 7, 2019 were retrieved comprehensively. Observational studies related to TNF-alpha and CCR5 gene polymorphisms and influenza A(H1N1) pdm09 were collected. A strict quality evaluation was carried out according to NOS scale. Meta-analysis was performed using software Revman 5.0 and Stata 11.0. Results: After screening, a total of 8 studies were included in this Meta-analysis. The results showed that TNF-α gene polymorphism rs361525 might be associated with the risk of influenza A(H1N1)pdm09 virus infection (A vs. G: OR=2.25, 95%CI: 1.09-4.65, P=0.03; AA vs. GG: OR=4.34, 95%CI: 1.65-11.41, P=0.003; AA vs. AG+GG: OR=4.38, 95%CI: 1.67-11.48, P=0.003), similar trend also found in rs1800750 (AA+AG vs. GG: OR=2.42, 95%CI: 1.24-4.71, P=0.01). The results of subgroup analysis indicated that A allele and AA+AG genotypes of rs361525 were risk factors for influenza A(H1N1) pdm09 virus infection in Caucasians. AA genotype was a risk factor for influenza A(H1N1) pdm09 virus infection in Mexican (P<0.05). There was no significant difference in the genetic polymorphism of CCR5 and the severity of influenza A (H1N1) pdm09 virus indection (P>0.05). Conclusion: People with allele A or genotype AA at rs361525, genotype AA+AG at rs1800750 of TNF-α gene might be more susceptible to influenza A(H1N1) pdm09.