The fever will subside two or three days after symptoms develop, but then respiratory symptoms such as a runny nose and cough will develop. Having weaker immune systems, elderly people who catch the flu and more likely to become seriously ill, and may develop secondary infections such as bacterial pneumonia. In particular, in patients with underlying disorders of the heart or lungs, the flu can lead to hospitalization or death.
If you have these symptoms, you should go to a hospital for an examination as soon as possible. It is a link for moving within the page. Section Navigation. Facebook Twitter LinkedIn Syndicate. Understanding Flu Viruses. Minus Related Pages. More Information about Flu Viruses. Types of Flu Viruses Flu A and B viruses are responsible for seasonal flu epidemics more commonly known as the flu season.
Estimating influenza-related excess mortality and reproduction numbers for seasonal influenza in Norway, — ; Epidemiol Infect. Comparative community burden and severity of seasonal and pandemic influenza: results of the Flu Watch cohort study. Lancet Respir Med. Jefferson T, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses: systematic review.
BMJ ; Routes of influenza transmission. Influenza Other Respir Viruses. Use of oseltamivir in 12 European countries between and — lack of association with the appearance of oseltamivir-resistant influenza A H1N1 viruses. Euro Surveill. Treatment with neuraminidase inhibitors for critically ill patients with influenza A H1N1 pdm Clin Infect Dis.
Face mask use and control of respiratory virus transmission in households. Oseltamivir-resistant influenza A H1N1 virus, Europe, —08 season. Moscona A Oseltamivir resistance — disabling our influenza defences. NEJM ; Influenza-related deaths — available methods for estimating numbers and detecting patterns for seasonal and pandemic influenza in Europe.
Early estimates of the excess mortality associated with the influenza season in Portugal. The burden of influenza-associated critical illness hospitalizations. Crit Care Med. Influenza activity in Europe during eight seasons : an evaluation of the indicators used to measure activity and an assessment of the timing, length and spread across Europe. BMC Infectious Diseases. Mortality associated with influenza and respiratory syncytial virus in the United States.
Textbook of Influenza. Hospitalizations associated with influenza and respiratory syncytial virus in the United States, Influenza-associated excess mortality in Germany, Emerg Themes Epidemiol. The information contained in this factsheet is intended for the purpose of general information and should not be used as a substitute for the individual expertise and judgement of healthcare professionals when it comes to patient care.
Microbiology and laboratory reports; External quality assessments, Influenza virus characterisations. Vaccination is the most effective form of influenza prevention.
Apart from vaccination and antiviral treatment the public health management includes personal protective measures. Seasonal influenza is a vaccine-preventable disease and annual influenza vaccination is the most effective way to prevent influenza. ECDC continues to emphasise that all Europeans who are recommended to have the influenza vaccine should get vaccinated.
Vaccination is especially important for people at higher risk of serious influenza complications: Individuals with specific chronic medical conditions, pregnant women, and children aged months, the elderly and healthcare workers. Although vaccination is the preferred option for preventing influenza, antivirals can be useful when the vaccine fails.
Partners and networks working with influenza prevention and control. The network combines epidemiological and virological surveillance of influenza. Factsheet Questions and answers on seasonal influenza Key messages. Factsheet about seasonal influenza Factsheet. Twitter Facebook Linked In Mail. The pathogen Influenza viruses are RNA viruses from the family Orthomyxoviridae , and have a worldwide distribution.
Influenza A viruses are further divided into subtypes. Antibodies against these glycoproteins are associated with immunity against influenza. Type B viruses cause somewhat less severe disease and tend to cause fewer complications than some type A viruses. Type B does not have subtypes but two antigenically distinct lineages: Victoria and Yamagata.
Type C viruses cause some human disease but only comparatively few outbreaks. Clinical features and sequelae Uncomplicated seasonal influenza disease Uncomplicated seasonal influenza disease presents as rapid onset of the following combination of systemic and respiratory symptoms: fever or feverishness; headache; muscle pain; general feeling of ill-health; runny nose; sore throat; non-productive cough. Severe influenza In some cases the disease becomes more severe due to the influenza virus infection or a secondary, usually bacterial, infection e.
Furthermore, exacerbations of underlying disease, e. Apart from the age-related increased risk, the risk of complications is increased for people of any age with particular chronic medical conditions: metabolic diseases e.
Epidemiology Influenza A and B Type A viruses are responsible for the highest burden of disease during seasonal epidemics, although both influenza A and B types are able to cause epidemics, significant disease and deaths. Type B infections are less common and usually milder than influenza A H3N2. RIDTs cannot distinguish between seasonal influenza A virus infections and animal-origin influenza A virus infections, and their sensitivity to detect these animal-origin influenza viruses, including avian or variant influenza viruses, can vary by test type and virus subtype.
Therefore, a negative RIDT result does not rule out influenza virus infection, and health care providers should not rely on a negative RIDT result to make decisions about treatment. Nucleic acid assays are the most sensitive diagnostic assays. However, no commercially available influenza diagnostic assay can specifically diagnose influenza variant virus or avian virus infection. Thus, if infection with these viruses is suspected, the state health department or CDC should be contacted.
The decision to start antiviral treatment should not be delayed while waiting for results of confirmatory laboratory testing. Early antiviral treatment can shorten the duration of fever and other symptoms and reduce the risk of complications from influenza. Antiviral treatment is recommended as early as possible for any patient with confirmed or suspected influenza who is hospitalized; has severe, complicated, or progressive illness; or is at a higher risk for influenza-associated complications www.
Antiviral treatment can also be considered for any previously healthy patient with confirmed or suspected influenza not at high risk of complications. Treatment is most effective if it can be initiated within 48 hours of illness onset. Four FDA-approved antiviral agents are recommended for the treatment and prophylaxis of influenza: oral oseltamivir available as generic or Tamiflu, Genentech , inhaled zanamivir Relenza, GlaxoSmithKline , intravenous IV peramivir Rapivab, BioCryst Pharmaceuticals , and oral baloxavir Xofluza, Genentech.
Three of the antiviral medications are neuraminidase inhibitors that have activity against both influenza A and B viruses; baloxavir is an endonuclease inhibitor that also has activity against both influenza A and B viruses. Oseltamivir is recommended for treatment for all ages and is the preferred agent to treat patients with severe or complicated influenza illness who are able to tolerate oral medications. Inhaled zanamivir is not recommended for use in people with underlying chronic respiratory disease.
Baloxavir is indicated to treat acute uncomplicated influenza in patients 12 years of age or older who have been symptomatic for no more than 48 hours Table Two other FDA-approved anti-influenza medications, amantadine and rimantadine, are not recommended for treatment or prophylaxis of influenza because of widespread viral resistance among circulating influenza A viruses.
Amantadine and rimantadine are not active against influenza B viruses. People at increased risk for complications of influenza should discuss antiviral treatment with their health care provider before travel to areas where influenza activity is occurring.
Antiviral drugs can also be used for prophylaxis, to prevent infection after close contact with a confirmed case; however, CDC does not recommend routine use of antiviral medications for prophylaxis except as one of multiple interventions to control institutional influenza outbreaks.
Postexposure prophylaxis should be initiated within 48 hours of exposure and never later than 48 hours, because of the risk of treating infection with a subtherapeutic dose. CDC recommendations for antiviral use for variant virus infections are similar to seasonal influenza virus infection www. Recommendations for exposure prophylaxis of close contacts of confirmed human infections of avian influenza A H5N1 and A H7N9 viruses are available at www.
However, prophylaxis can be considered based on clinical judgment, with consideration given to the type of exposure and to whether the exposed person is at high risk for complications from influenza. If antiviral prophylaxis is initiated, twice daily treatment dosing for oseltamivir or zanamivir is recommended instead of once daily prophylaxis dosing www.
Several influenza vaccines are approved for use in the United States www. For updates and the following season recommendations, providers should access www. For people for whom more than one type of vaccine is indicated, there is no preference for any particular category.
IIV can be administered by intramuscular injection, transdermally via needle-free jet injector, or intradermal injection depending on the product. LAIV is administered as a nasal spray and is labeled for use in people aged 2—49 years. Influenza vaccine composition can be trivalent, protecting against 3 different influenza viruses 2 influenza subtype A and 1 type influenza B , or quadrivalent, with protection against 4 different influenza viruses 2 influenza A subtypes and 2 influenza type B lineages.
Quadrivalent vaccine includes a representative strain from 2 antigenically distinct influenza B lineages, B-Yamagata and B-Victoria. No information is available about the benefits of revaccinating people before summer travel who were vaccinated during the preceding fall, and revaccination is not recommended. People at higher risk for influenza complications should consult with their health care provider to discuss the risk for influenza or other travel-related diseases before traveling during the summer.
Seasonal influenza vaccines are not expected to provide protection against human infection with animal-origin influenza viruses, including avian influenza A H5N1 and H7N9 viruses. No commercially available influenza vaccines are available to protect against avian or swine influenza viruses.
The most frequent side effects of vaccination with intramuscular and intradermal IIV in adults are soreness and redness at the vaccination site. These local injection-site reactions are slightly more common with vaccine administered intradermally, with needle-free jet injection and with high-dose IIV.
They generally are mild and rarely interfere with the ability to conduct usual activities.
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