Flu: Facts about seasonal influenza and bird flu

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The fluis a transmissible viral transmission of the respiratory system that affect the nose , pharynx and lungs . It is make by flu virus .

symptom of mild flu infection can resemble those of the common cold , which is also make by viruses ; that read , grippe symptoms tend to be more intensethan cold symptoms and come on quicker . And in severe case , flu symptoms can be serious enough to lead to hospitalization and death .

Image of five influenza viruses, depicted in bright colors

“The flu,” or seasonal influenza, is caused by influenza viruses, like those pictured above.

Flu viruses are categorized into four type : A , B , C and D. Types A and atomic number 5 are the most harmful to homo and have seasonal flu epidemics ; in the Northern Hemisphere , flu season typically occurs from October to May , with peak activityfrom December to February .

flu C can also infect people but causes very mild illness and is not associated with epidemic , while type D move cattle and other animal and is not love to cause illness in human .

Flu spreads between masses via viral corpuscle in droplet throw out when an septic soul cough or sneeze , or through saliva commute via shared utensils or kissing .

A woman sits on the couch under a blanket and blows her nose

Some early symptoms of the flu can resemble symptoms people experience during a cold.

Each year , seasonal flu nauseate about1 billion people worldwideand causes approximately290,000 to 650,000 respiratory deaths . In a given season , the U.S. seesabout 200,000 hospitalizations and 36,000 deaths from flu , although these numbers vary twelvemonth to year .

With rare exceptions , seasonal vaccines arerecommended for everyone 6 calendar month and olderto invalidate illness and to prevent serious ramification from flu . Hand - washing , avoiding link with macabre the great unwashed and dissemble while in public can also lose weight the risk of infection .

Facts about the flu

Everything you need to know about the flu

What are the symptoms of flu?

Although grippe is primarily a respiratory illness , its symptoms affect the entire body .

Fever is one of the most vernacular flu symptom , and it ordinarily lasts forthree to four days . Other symptoms include shudder , knockout headache , sore throat , coughing , chest discomfort , and a close or runny nose . Flu also brings musculus aches and extreme weariness . In some instances , flu may cause vomiting or diarrhea ; this occurs more often in children than in adult .

Symptoms motley from person to person , and they may be mild or very grave . In some cases , flu can lead to pneumonia , a knockout lung infection , and require hospitalization ; it can also raise the peril of serious subaltern contagion frombacteria . hoi polloi are more at risk of developing serious ramification from flu if they have one or more underlying wellness precondition , such as diabetes ; asthma or continuing lung disease ; heart or blood disease ; and liver or kidney disorders .

A microscopic image of flu virus proteins as the virus’s genetic material is being copies; the components are shown in green, orange and blue

(Image credit: Image courtesy of the Wilson, Carragher and Potter labs)

Flu is more dangerous in masses who are fraught or who are long time 65 or older . Children under 5 are vulnerable to severe influenza , and those under 2 are at peculiarly high-pitched risk for grow serious unwellness . Having a counteract resistant system due to disease or certain medical treatment , such as chemotherapy , can also raise the risks of life - menace complication .

What’s the difference between a cold and the flu?

influenza and low temperature are themost common respiratory infections in the United States . Both bear on the tissue of the nozzle and throat , and both are due to viruses and go around easily between multitude . However , there are some key divergence between coldness and the flu .

cold are cause by approximately200 different viruses , including rhinovirus , adenoviruses andcoronaviruses(a broad group of viruses that includes the germ behind COVID-19 ) .

Cold symptoms usually appearwithin one to three daysof being infect and are mild at the start . They often let in a tickle in the throat , sneeze , and a runny or stuffy nozzle . Symptoms typically peak within a week of onset , around Day 4 to 7 . Headache or fever may develop , but these symptoms are rarified in cold . A low temperature ’s average duration is eight to 10 mean solar day . Most common cold go off on their own , but over - the - rejoinder medications can aid relieve symptoms and concentrate pain .

black and white photo of a hospital ward with four long rows of beds stretching away from the camera

(Image credit: National Archives)

Flu get along on quicker than a coldness . In flu , fever , iciness , headaches , torso aching and enfeeblement are typically the first symptoms to appear . Flu infections can cause virulent complications and can exacerbate live aesculapian conditions , such asasthma , congestive heart failure or diabetes .

There are no medications to foreclose or directly treat the common common cold , whereas grippe can be keep through seasonal vaccine and can be treated within the first 48 60 minutes of infection with theantiviral medicine oseltamivir , advantageously known asTamiflu .

How long does the flu last?

grippe symptom typically appear aboutone to four daysafter pic to the virus , but flu symptom can rapidly become severe . If the infected person is otherwise healthy , symptom usually lastfrom a few 24-hour interval to almost two weeks , although being vaccinated and have Tamiflu can shorten their length . Flu symptoms may last longer in some cases and can cause tiredness that persistseven after other symptom have ended .

For most hoi polloi , a bout of flu is unpleasant and uncomfortable but not lifetime - sullen . However , complications can uprise that may protract illness . Some complications are moderate , such as ear andsinus infections .

Other complications are more serious , such as viral or bacterial pneumonia . This inflammation of the lungs happens when the lung sacs , known as alveoli , take with fluid and hinder breathing . Recovery from pneumonia cantake up to a month or foresighted . Flu can also spark off sepsis , an extreme , body - blanket resistant reaction . Runaway inflammation driven by sepsis can lead to tissue damage and fatal organ unsuccessful person .

image of four flu virus particles, depicted in blue on a red background

(Image credit: NIAID/NIH)

What’s the difference between influenza A and influenza B?

Bird flu , or avian grippe , is triggered by flu A viruses . Flu viruses that taint world and birds are both categorized by their Planck’s constant and N proteins , but avian grippe viruses taint razzing as their primary host .

All of the grippe A subtypes are chance in razzing , with two exception : subtypesH17N10 and H18N11 , which take place only in bats . A handful of subtypes of avian influenza A viruses are known to now and then taint humans : H5 , H6 , H7 , H9 and H10 .

Flu spreads between bird through striking with septic saliva , respiratory droplets or feces . Some melodic line of avian flu cause meek sickness in birds ; others are pestilent . Infected birdsmay sneeze or coughing , arise swelling in various body function , and seem uncoordinated or lethargic . That read , some birds can carry and spread influenza virus without fall sick themselves .

swine flu particles, depicted in blue, budding off the surface of a cell, shown in orange

(Image credit: National Institute of Allergy and Infectious Diseases/NIH)

In people , avian influenza symptom resemble those of seasonal influenza and can range from mild to severe , sometimes turning deadly . Symptoms also may let in conjunctivitis — eye irritation and redness .

There are breed of bird flu that affect cattle andmay be able to sickenpeople who booze raw milkfrom infect Bos taurus .

mortal - to - person transmission of bird flu has historically been reported in obscure cases involving one to two individual , but not during the ongoing outbreak in the U.S. Avian flu does not spread easily from mortal to person , but there is a farm risk that bird flu couldmutate to become more contagiousin world , levy the risk of a bird grippe pandemic .

a photo of a doctor providing a vaccine to a young woman, a clinical trial participant, while a second woman looks on in the background

(Image credit: National Institute of Allergy and Infectious Diseases/NIH)

Glossary

Flu pictures

grippe virus proteins in the enactment of self - reproduction , captured with a microscope . The blue protein encloses the computer virus ’s RNA ( green ) , its genetic textile . An enzyme ( orange ) is reading and making copy of the RNA , which is necessary for fix copy of the computer virus .

soldier with influenza at the infirmary in Camp Funston , Kansas , in 1918 . Camp Funston is where the grippe epidemic first made a major appearance . Troops from the coterie carry the computer virus to other Army bases during World War I. The epidemic killed more than 50 million hoi polloi worldwide , including 675,000 Americans .

Colorized transmission negatron micrograph of flu A / H1N1 virus particle ( blasphemous ) . Influenza A / H1N1 can taint both humans and animals , including doll and fuzz , and is one of several strains related to seasonal influenza outbreaks .

Sick woman blowing her nose while covered with a blanket.

A colorized transmission electron micrograph evidence swine grippe virus particles ( blue ) impound to and bud off of a cell ( orange ) .

A intelligent volunteer receives an data-based cosmopolitan influenza vaccine as part of an early - stage clinical test at the National Institutes of Health ( NIH ) Clinical Center in Bethesda , Maryland . scientist at NIAID ’s Vaccine Research Center ( VRC ) developed the vaccine .