Chest
Henry J. Woodford in Essential Geriatrics, 2022
Influenza is caused by an RNA virus of the Orthomyxoviridae family. It is more likely to produce serious illness in older adults due to immune senescence and the high prevalence of co-morbidities. It may spread rapidly in nursing home environments. Outbreaks are increased in the winter (typically between November and April in the northern hemisphere). It, classically, presents with a cough and fever, following a two-day incubation period. Death may result from secondary bacterial pneumonia (thought to be responsible for over 90% of influenza-related deaths in the over 65s). It affects around 5–20% of the population each year. The virus has two glycoproteins on its surface. These are haemagglutinin, which allows adhesion of the virus to respiratory epithelial cells and subsequent viral entry, and neuraminidase, which is an enzyme involved in the release of newly formed virions from the host cell (seeFigure 21.1).
Influenza neurologic complications
Avindra Nath, Joseph R. Berger in Clinical Neurovirology, 2020
Influenza viruses are members of the Orthomyxoviridae family. There are three types of influenza viruses that can infect humans: A, B, and C. Influenza types B and C primarily infect humans, whereas influenza A viruses infect a wide variety of mammals (including humans, horses, pigs, ferrets, cats, and dogs) as well as avian species. The ability of influenza A viruses to infect such a wide variety of host species that frequently come into close contact with one another permits the occurrence of co-infections with multiple influenza A viruses in permissive hosts that can serve mix the different influenza RNA segments. The genome of influenza viruses consists of seven to eight segments of negative-sense single-stranded RNA contained within an envelope to form a virus particle (virion) that is polymorphic and can be spherical or filamentous in morphology [1]. Co-infections can result in genetic reassortant viruses that express novel antigenic properties, which can cause periodic epidemics in immunologically naive populations. In some instances, these new viruses cause epidemics and can spread rapidly and widely enough to be considered as a pandemic.
Influenza
James M. Rippe in Lifestyle Medicine, 2019
Influenza viruses are members of the family Orthomyxoviridae. There are three types of influenza virus: influenza A, influenza B, and influenza C. Influenza viruses have been divided into these three types on the basis of major antigenic differences in the nucleoprotein (NP) and matrix (M) protein antigens. Influenza A viruses are the most virulent of the three influenza viruses and are the etiologic agents of all known influenza pandemics. Influenza B virus tends to cause milder disease than influenza A.2 Influenza C virus causes infection in humans only infrequently, and its pattern of infection follows no seasonal variation. All three types of virus exhibit a host-cell-derived lipid envelope and a genome of segmented, negative sense single-stranded RNA. Influenza viral particles are variable in shape, from irregular spheres that measure 80–120 nm in diameter to long filamentous particles. Only influenza A viruses are subtyped. Influenza A is subtyped on the basis of two major surface proteins, neuraminidase (NA) and hemagglutinin (HA). These surface proteins project like spikes, densely covering the surface of the virus, and are important for cell entry. One additional protein, membrane protein M2, is also present in small amounts on the viral envelope. Influenza A viruses are named for their HA and NA surface proteins, for example, a virus called H3N2 will contain HA type 3 and NA type 2. In addition to subtype, influenza A viruses are further characterized on the basis of the place and time that the virus was first isolated (e.g., A/California/7/2009) (H1N1).
Cost-effectiveness of influenza vaccination with a high dose quadrivalent vaccine of the elderly population in Belgium, Finland, and Portugal
Published in Journal of Medical Economics, 2023
Fabián P. Alvarez, Pierre Chevalier, Matthias Borms, Hélène Bricout, Catia Marques, Anu Soininen, Tatu Sainio, Christine Petit, Caroline de Courville
Influenza is an acute respiratory infection caused by an RNA virus of the Orthomyxoviridae family. Usually, flu starts suddenly with a high fever, muscular soreness, headache, severe fatigue, general discomfort, and respiratory symptoms, such as dry cough, rhinorrhea. The illness lasts for about a week, but fatigue is frequently felt for two weeks or more1. A dry cough can persist for two weeks. Although benign in most cases, influenza may lead to severe complications or an aggravation of an already existing chronic disease (such as diabetes, chronic obstructive pulmonary disease, heart failure, chronic kidney disease2). Evidence shows that influenza increases the risk of pneumonia by 100 in the week following the infection, due to the influenza virus implication in the pathogenesis of several respiratory bacterial pathogens commonly associated with pneumonia3. In addition, a large number of published papers suggests that laboratory-confirmed influenza infection may be associated with an increased risk of acute myocardial infarction estimated as six times higher4. In a case-crossover analysis using California data, among 36,975 hospitalized ischemic strokes, the risk of stroke after an Influenza‐like illness (ILI) episode increased by almost three times in the days following the flu infection5.
Next generation live-attenuated influenza vaccine platforms
Published in Expert Review of Vaccines, 2022
Influenza viruses are an enveloped, single-stranded, segmented genome, negative-sense RNA virus that belongs to the family Orthomyxoviridae. Influenza viruses have four major types: A, B, C, and D viruses, based on antigenic differentiation in nucleoprotein (NP) and matrix (M) proteins. Influenza A virus (IAV) subtypes (HxNy) are classified based on the presence of surface glycoproteins, hemagglutinin (HA), and neuraminidase (NA) subtypes (H1 through H18, and N1 through N11) (A1RP). IAV subtypes are endemic in humans and infect many other species [1]. Influenza B viruses (IBV) infect humans, seals, and ferrets [2,3]. Influenza C viruses (ICV) are less common and infect pigs, dogs, and humans, and influenza D viruses (IDV) are less common and infect cattle, goats, and pigs [4].
Microneedles enable the development of skin-targeted vaccines against coronaviruses and influenza viruses
Published in Pharmaceutical Development and Technology, 2022
Thuy Trang Nguyen, Thi Thuy Dung Nguyen, Nguyen-Minh-An Tran, Huy Truong Nguyen, Giau Van Vo
The SARS-CoV-1, SARS-CoV-2 and influenza are well known to cause contagious respiratory illnesses and share some symptoms such as coughing, fever, and tiredness. Influenza viruses are enveloped viruses of the Orthomyxoviridae family, which are grouped into four genera, which include influenza virus A–D (IAV, IBV, ICV, and IDV). Among influenza viruses, type A and B v such as influenza A (H1N1) and influenza A (H3N2) have been recognized as a seasonal epidemics of the disease. Among the species, the emergence of pandemic H1N1 influenza in 2009, human infections with avian H7N9 influenza in 2013, and sporadic human cases of highly pathogenic avian H5N1 influenza (Webster and Govorkova 2014). Currently, two available influenza vaccines have been marketed including the trivalent inactivated influenza vaccine (TIV) administered intramuscularly with syringes for using in ages > 6 months old and the live attenuated influenza vaccine (LIV) are provided as nasal spray. However, available influenza prevention through immunization in adults is hindered by low vaccination coverage, high immunization costs (Lee et al. 2015), and suboptimum vaccine effectiveness (Osterholm et al. 2012). Although many types of influenza vaccines are currently approved, improved delivery methods are needed to tackle these limitations.
Related Knowledge Centers
- Influenza A Virus
- Influenza C Virus
- Mucus
- Influenza
- Negative-Strand Rna Virus
- Rna Virus
- Influenza B Virus
- Influenza D Virus
- Thogotovirus
- Quaranjavirus