A report on Influenza

Influenza virus, magnified approximately 100,000 times
Symptoms of influenza, with fever and cough the most common symptoms
Influenza virus nomenclature (for a Fujian flu virus)
Structure of the influenza virion. The hemagglutinin (HA) and neuraminidase (NA) proteins are shown on the surface of the particle. The viral RNAs that make up the genome are shown as red coils inside the particle and bound to ribonucleoproteins (RNP).
Host cell invasion and replication by the influenza virus
Antigenic shift, or reassortment, can result in novel and highly pathogenic strains of human influenza.
How the different sites of infection (shown in red) of H1N1 and H5N1 influences their transmission and lethality
Giving an influenza vaccination
X-ray of 29-year-old person with H1N1
Influenza mortality in symptomatic cases in the US for the 2018/2019 season.
Seasonal risk areas for influenza: November–April (blue), April–November (red), and year-round (yellow)
The main types of influenza viruses in humans. Solid squares show the appearance of a new strain, causing recurring influenza pandemics. Broken lines indicate uncertain strain identifications.
The difference between the influenza mortality age distributions of the 1918 epidemic and normal epidemics. Deaths per 100,000 persons in each age group, United States, for the interpandemic years 1911–1917 (dashed line) and the pandemic year 1918 (solid line).
Thermal imaging camera and screen, photographed in an airport terminal in Greece during the 2009 flu pandemic. Thermal imaging can detect elevated body temperature, one of the signs of swine flu.
Professional examining a laboratory-grown reconstruction of the 1918 Spanish flu virus in a biosafety level 3 environment
Chinese inspectors checking airline passengers for fevers, a common symptom of swine flu

Infectious disease caused by influenza viruses.

- Influenza
Influenza virus, magnified approximately 100,000 times

49 related topics with Alpha

Overall

Diagram of influenza nomenclature

Influenza A virus

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Diagram of influenza nomenclature
A transmission electron micrograph (TEM) of the reconstructed 1918 pandemic influenza virus. The bottom structure represents membrane debris from the cells used to amplify the virus. Pictured are the 'elliptical' particles representing the smallest particles produced by influenza virus. Purification techniques often deform the particles without proper fixation protocols, leading to 'spherical' appearance. Filamentous or intermediate sized particles simply extend along the long axis on the opposite side of the genome segments.
Influenza A virus structure
Influenza A virus replication cycle
Timeline of flu pandemics and epidemics caused by influenza A virus
Genetic evolution of human and swine influenza viruses, 1918–2009

Influenza A virus (IAV) causes influenza in birds and some mammals, and is the only species of the genus Alphainfluenzavirus of the virus family Orthomyxoviridae.

Soldiers march in front of the Pomona College Carnegie Library during the Spanish flu pandemic in 1918, all garbed in uniforms and face masks.

Influenza A virus subtype H1N1

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Subtype of Influenza A virus.

Subtype of Influenza A virus.

Soldiers march in front of the Pomona College Carnegie Library during the Spanish flu pandemic in 1918, all garbed in uniforms and face masks.
Illustration of influenza antigenic shift

Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza, for instance in 2004–2005.

Influenza A virus structure

Orthomyxoviridae

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Family of negative-sense RNA viruses.

Family of negative-sense RNA viruses.

Influenza A virus structure
Influenzavirus genomes. Segments translate to polymerase (PB1, PB2, and PA), hemagglutinin (HA), neuramindase (NA), nucleoprotein (NP), membrane protein (M), and non-structural protein (NS).
Infection and replication of the influenza virus. The steps in this process are discussed in the text.
Transcription of mRNAs initiated by viral polymerase using cap snatching
Diagram of influenza nomenclature
Host range of influenza viruses
Targets of anti-influenza agents that are licensed or under investigation

The first four genera contain viruses that cause influenza in birds (see also avian influenza) and mammals, including humans.

Soldiers sick with Spanish flu at a hospital ward, Camp Funston, Fort Riley, Kansas

Spanish flu

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Exceptionally deadly global influenza pandemic caused by the H1N1 influenza A virus.

Exceptionally deadly global influenza pandemic caused by the H1N1 influenza A virus.

Soldiers sick with Spanish flu at a hospital ward, Camp Funston, Fort Riley, Kansas
Public health recommendations from the 1918 Illustrated Current News, New Haven, CT
Front page of El Sol (Madrid), 28 May 1918: "The three-day fever. 80,000 infected in Madrid. H.M. the king is sick."
The Times (London) front page 25 June 1918: "The Spanish Influenza"
Advertisement in The Times 28 June 1918 for Formamint tablets to prevent 'Spanish influenza'
"Spanish influenza," "three-day fever," "the flu." by Rupert Blue, U.S. Surgeon General, 28 September 1918
Seattle policemen wearing white cloth face masks during the Spanish flu pandemic, December 1918
American Expeditionary Force victims of the Spanish flu at U.S. Army Camp Hospital no. 45 in Aix-les-Bains, France, in 1918
American Red Cross nurses tend to flu patients in temporary wards set up inside Oakland Municipal Auditorium, 1918.
Edvard Munch (1863–1944), Self-Portrait with the Spanish Flu (1919)
Egon Schiele (1880–1918), Die Familie (The Family), painted a few days before his death, just after that of his wife Edith.
As U.S. troops deployed en masse for the war effort in Europe, they carried the Spanish flu with them.
US Army symptomology of the flu
Coughs and sneezes spread diseases. U.S. Public Health ad on dangers of Spanish Flu epidemic during World War I.
Difference between the influenza mortality age-distributions of the 1918 epidemic and normal epidemics – deaths per 100,000 persons in each age group, United States, for the interpandemic years 1911–1917 (dashed line) and the pandemic year 1918 (solid line)
Three pandemic waves: weekly combined influenza and pneumonia mortality, United Kingdom, 1918–1919
A chart of deaths from all causes in major cities, showing a peak in October and November 1918
Japanese women wear white gauze face masks during the Spanish flu pandemic in Tokyo, Japan, 1919
A nurse wears a cloth mask while treating a patient in Washington, DC
Alberta's provincial board of health poster
1918 influenza epidemic burial site in Auckland, New Zealand
An electron micrograph showing recreated 1918 influenza virions
At the Centers for Disease Control and Prevention, Terrence Tumpey examines a reconstructed version of the Spanish flu.

The virus was particularly deadly because it triggered a cytokine storm, ravaging the stronger immune system of young adults, although the viral infection was apparently no more aggressive than previous influenza strains.

Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)

Pneumonia

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Inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.

Inflammatory condition of the lung primarily affecting the small air sacs known as alveoli.

Chest X-ray of a pneumonia caused by influenza and Haemophilus influenzae, with patchy consolidations, mainly in the right upper lobe (arrow)
Main symptoms of infectious pneumonia
The bacterium Streptococcus pneumoniae, a common cause of pneumonia, imaged by an electron microscope
Cavitating pneumonia due to MRSA as seen on a CT scan
A chest x-ray of a patient with severe viral pneumonia due to SARS
Pneumonia fills the lung's alveoli with fluid, hindering oxygenation. The alveolus on the left is normal, whereas the one on the right is full of fluid from pneumonia.
A chest X-ray showing a very prominent wedge-shaped area of airspace consolidation in the right lung characteristic of acute bacterial lobar pneumonia
CT of the chest demonstrating right-sided pneumonia (left side of the image)
A pleural effusion: as seen on chest X-ray. The A arrow indicates fluid layering in the right chest. The B arrow indicates the width of the right lung. The volume of the lung is reduced because of the collection of fluid around the lung.
Deaths from lower respiratory infections per million persons in 2012
WPA poster, 1936/1937
Pneumonia seen by ultrasound
Right middle lobe pneumonia in a child as seen on plain X-ray
Disability-adjusted life year for lower respiratory infections per 100,000 inhabitants in 2004 
no data
less than 100
100–700
700–1,400
1,400–2,100
2,100–2,800
2,800–3,500
3,500–4,200
4,200–4,900
4,900–5,600
5,600–6,300
6,300–7,000
more than 7,000

Vaccines to prevent certain types of pneumonia (such as those caused by Streptococcus pneumoniae bacteria, linked to influenza, or linked to COVID-19) are available.

The different sites of infection (shown in red) of seasonal H1N1 versus avian H5N1 influences their lethality and ability to spread.

Influenza A virus subtype H5N1

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Subtype of the influenza A virus which can cause illness in humans and many other animal species.

Subtype of the influenza A virus which can cause illness in humans and many other animal species.

The different sites of infection (shown in red) of seasonal H1N1 versus avian H5N1 influences their lethality and ability to spread.
The H in H5N1 stands for "hemagglutinin", as depicted in this molecular model
The N in H5N1 stands for "Neuraminidase", the protein depicted in this ribbon diagram
Transmission electron micrograph (TEM) of negatively stained Influenza A virus particles (small and white) attached to host cells (large and irregular) (late passage). (Source: Dr. Erskine Palmer, Centers for Disease Control and Prevention Public Health Image Library)
Highly pathogenic H5N1
Countries with humans, poultry and wild birds killed by H5N1
Countries with poultry or wild birds killed by H5N1 and has reported human cases of H5N1
Countries with poultry or wild birds killed by H5N1

In general, humans who catch a humanized influenza A virus (a human flu virus of type A) usually have symptoms that include fever, cough, sore throat, muscle aches, conjunctivitis, and, in severe cases, breathing problems and pneumonia that may be fatal.

Influenza C virus

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Influenza C virus is the only species in the genus Gammainfluenzavirus, in the virus family Orthomyxoviridae, which like other influenza viruses, causes influenza.

An oseltamivir capsule

Oseltamivir

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An oseltamivir capsule
A package of capsules
Plate from François-Pierre Chaumeton's 1833 "Flore Medicale"
Marketing display used at festivals features a person living in a hermetically sealed environment

Oseltamivir, sold under the brand name Tamiflu, is an antiviral medication used to treat and prevent influenza A and influenza B, the viruses that cause the flu.

Mexican soldiers distributing protective masks to citizens

2009 swine flu pandemic

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Third recent flu pandemic involving the H1N1 virus (the first being the 1918–1920 Spanish flu pandemic and the second being the 1977 Russian flu).

Third recent flu pandemic involving the H1N1 virus (the first being the 1918–1920 Spanish flu pandemic and the second being the 1977 Russian flu).

Mexican soldiers distributing protective masks to citizens
President Barack Obama being vaccinated against H1N1 flu on 20 December 2009
Flu inspection on a flight arriving in China
Thermal imaging camera and screen, photographed in an airport terminal in Greece. Thermal imaging can detect elevated body temperature, one of the signs of swine flu.
Mexico City Metro
Osaka Loop Line, Japan
President Obama at Homeland Security Council meeting in Cabinet Room to discuss the H1N1 flu on 1 May 2009

The symptoms of H1N1 flu are similar to those of other influenzas, and may include fever, cough (typically a "dry cough"), headache, muscle or joint pain, sore throat, chills, fatigue, and runny nose.

Pigs can harbor influenza viruses adapted to humans and others that are adapted to birds, allowing the viruses to exchange genes and create a pandemic strain.

Influenza A virus subtype H3N2

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Pigs can harbor influenza viruses adapted to humans and others that are adapted to birds, allowing the viruses to exchange genes and create a pandemic strain.
The influenza viruses that caused Hong Kong flu (magnified about 100,000 times)
Diagram of influenza virus nomenclature

Influenza A virus subtype H3N2 (A/H3N2) is a subtype of viruses that causes influenza (flu).