The fever may subside once during the course of the illness as if the flu had run its course, only to reappear half a day to a day later.
The condition begins with a sudden high fever and then strong systemic symptoms such as sore throat, headache, joint pain, and malaise. 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.
Humans infected with variant influenza viruses have a clinical presentation similar to human influenza virus infections. Reported human infections with avian influenza A H5N1 or A H7N9 viruses often have severe pneumonia or respiratory failure and a high case-fatality ratio. Influenza can be difficult to distinguish from respiratory illnesses caused by other pathogens on the basis of signs and symptoms alone.
Diagnostic tests available for influenza include viral culture, rapid influenza diagnostic tests RIDTs , immunofluorescence assays, and nucleic acid—based assays, such as RT-PCR www. Most patients with clinical illness consistent with uncomplicated influenza in an area where influenza viruses are circulating do not require diagnostic testing for clinical management. Patients who should be considered for influenza diagnostic testing include the following:. 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.
Our service is free and we are here to help you. Flu Symptoms, Causes, and Risk Factors. Section Menu. What Are the Symptoms of Influenza? Symptoms of influenza can include: Sudden onset of high fever Headache, muscle aches and joint pain Cough usually dry Chills Sore throat Nasal congestion and runny nose Fatigue Stomach symptoms such as nausea, vomiting or diarrhea may occur but are more common in children than adults. Flu symptoms in children Flu symptoms in school-age children and adolescents are similar to those in adults.
What Causes the Flu? Flu Risk Factors Influenza is a very serious illness for anyone at high risk. Certain diseases that place people at high risk include: chronic lung diseases such as asthma , COPD , bronchiectasis , or cystic fibrosis heart disease chronic kidney disease diabetes or other chronic metabolic disorder morbid obesity severe anemia including sickle cell anemia diseases HIV, AIDS or treatments steroids, chemotherapy that suppress immunity liver disorders children and adolescents who are receiving long-term aspirin therapy.
Learn more. When to See Your Doctor For your yearly flu shot. See a doctor if you: Have difficulty breathing; Experience chest pain as a result of coughing; or Are coughing up yellow, green or bloody phlegm.
Previous: Learn About Flu. Next: Diagnosing and Treating Flu. Make a Donation Your tax-deductible donation funds lung disease and lung cancer research, new treatments, lung health education, and more. What CDC Does. To receive weekly email updates about Seasonal Flu, enter your email address: Email Address. What's this? Links with this icon indicate that you are leaving the CDC website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
You will be subject to the destination website's privacy policy when you follow the link.
0コメント