Influenza C viruses cause only mild respiratory infections and are not thought to be responsible for epidemics. Influenza A viruses are the most harmful, as they can cause severe disease. Wild aquatic birds are often the hosts for a large variety of influenza A viruses.
Sometimes these viruses are transmitted from bird to human and can cause devastating outbreaks. Some of the subtypes of influenza A that have caused the largest number of known human deaths are: 14, Influenza B almost exclusively infects humans and is less common than influenza A.
This means washing hands , avoiding extended contact with infected individuals, disinfecting infected surfaces, etc. Beyond that, the most effective line of defense is the influenza vaccine flu shot.
There are two types. A trivalent vaccine protects against two influenza A strains H1N1 and H3N2 and one influenza B strain, while a quadrivalent vaccine prevents against those three plus one more type B strain.
Strains of influenza A H3N2 can mutate quickly, though, so health officials have to anticipate its evolution every year. As a result, the seasonal flu vaccine can be less effective in preventing type A infections if that prediction is off. Taking the same general precautions washing hands, avoiding sick individuals, etc.
The flu vaccine is typically a safe bet for influenza B, but it might not always be a perfect match for the annual strain. Getting a flu shot will not infect someone with influenza A or B. The vaccines contain dead viruses or a single influenza protein, or in the case of the nasal spray vaccine weakened live virus, none of which are enough to infect a human.
A majority of people will ride out the flu from home with only mild-to-moderate symptoms. A healthcare provider might also be necessary for individuals with severe or prolonged symptoms or other complications like difficulty breathing, chest pain, sudden dizziness, vomiting, neck stiffness, or loss of consciousness.
Influenza type A and type B are similar, but type A is overall more prevalent, sometimes more severe, and can cause flu epidemics and pandemics. Influenza A is a virus, although it may present with similar symptoms of common respiratory bacterial infections, like sinusitis.
Symptoms typically last five to seven days, although they can linger for up to two weeks. Getting a pre-emptive flu shot or taking antiviral medications can help shorten the duration. People with the flu are contagious one day before symptoms develop and five to seven days after that. In most cases, yes. Generally, it will run its course in seven to 10 days. High-risk individuals children, the elderly, those with pre-existing conditions, etc.
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Symptoms tend to develop 2 days after the illness starts, so a person may pass on the flu before they feel sick. For a person who is generally healthy, the flu is not typically dangerous.
However, it can severely affect certain groups of people, who should seek medical attention as soon as they suspect that they have flu symptoms. Those most at risk of developing flu complications include:. Many people believe that influenza A is more severe than influenza B. However, this is not always the case. A study concluded that adults hospitalized with influenza A or B tended to have similarly long hospital stays.
They also had similar rates of intensive care unit admission and death during hospitalization. A study found that the influenza B virus was more likely to cause death in hospitalized children aged 16 or younger. The researchers also concluded that children aged 10—16 years with this type of virus were more likely to be admitted to intensive care units, compared with those who had influenza A. Many people find that home remedies can help ease flu symptoms, but prescription antiviral medication may be a good idea for people with a high risk of complications or severe symptoms.
Antiviral medications are available by prescription only. They can shorten the duration of symptoms or prevent complications, such as pneumonia. Antivirals can especially benefit people with a greater risk of flu complications, including young children, older adults, pregnant women, and people with certain chronic illnesses. Antiviral medications work best when a person takes them within 1—2 days of symptoms starting. The best method of prevention is to receive a flu vaccination every year.
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