vaccine and circulating strains, or during an outbreak in a closed setting regardless of vaccination history. infection control hand hygiene is important in reducing the spread of influenza. this includes frequent hand washing with soap and water, using alcohol-based hand sanitizers, and not touching one's eyes, nose, and mouth with one's hands. covering one's nose and mouth when coughing or sneezing is important. other methods to limit influenza transmission include staying home when sick, avoiding contact with others until one day after symptoms end, and disinfecting surfaces likely to be contaminated by the virus, such as doorknobs. health education through media and posters is often used to remind people of the aforementioned etiquette and hygiene. there is uncertainty about the use of masks since research thus far has not shown a significant reduction in seasonal influenza with mask usage. likewise, the effectiveness of screening at points of entry into countries is not well researched. social distancing measures such as school closures, avoiding contact with infected people via isolation or quarantine, and limiting mass gatherings may reduce transmission, but these measures are often expensive, unpopular, and difficult to implement. consequently, the commonly recommended methods of infection control are respiratory etiquette, hand hygiene, and mask wearing, which are inexpensive and easy to perform. pharmaceutical measures are effective but may not be available in the early stages of an outbreak. in health care settings, infected individuals may be cohorted or assigned to individual rooms. protective clothing such as masks, gloves, and gowns is recommended when coming into contact with infected individuals if there is a risk of exposure to infected bodily fluids. keeping patients in negative pressure rooms and avoiding aerosol-producing activities may help, but special air handling and ventilation systems are not considered necessary to prevent the spread of influenza in the air. in residential homes, new admissions may need to be closed until the spread of influenza is controlled. when discharging patients to care homes, it is important to take care if there is a known influenza outbreak. since influenza viruses circulate in animals such as birds and pigs, prevention of transmission from these animals is important. water treatment, indoor raising of animals, quarantining sick animals, vaccination, and biosecurity are the primary measures used. placing poultry houses and piggeries on high ground away from high-density farms, backyard farms, live poultry markets, and bodies of water helps to minimize contact with wild birds. closure of live poultry markets appears to the most effective measure and has shown to be effective at controlling the spread of h5n1, h7n9, and h9n2. other biosecurity measures include cleaning and disinfecting facilities and vehicles, banning visits to poultry farms, not bringing birds intended for slaughter back to farms, changing clothes, disinfecting foot baths, and treating food and water. if live poultry markets are not closed, then "clean days" when unsold poultry is removed and facilities are disinfected and "no carry-over" policies to eliminate infectious material before new poultry arrive can be used to reduce the spread of influenza viruses. if a novel influenza viruses has breached the aforementioned biosecurity measures, then rapid detection to stamp it out via quarantining, decontamination, and culling may be necessary to prevent the virus from becoming endemic. vaccines exist for avian h5, h7, and h9 subtypes that are used in some countries. in china, for example, vaccination of domestic birds against h7n9 successfully limited its spread, indicating that vaccination may be an effective strategy if used in combination with other measures to limit transmission. in pigs and horses, management of influenza is dependent on vaccination with biosecurity. diagnosis x-ray of 29-year-old person with h1n1 diagnosis based on symptoms is fairly accurate in otherwise healthy people during seasonal epidemics and should be suspected in cases of pneumonia, acute respiratory distress syndrome (ards), sepsis, or if encephalitis, myocarditis, or breaking down of muscle tissue occur. because influenza is similar to other viral respiratory tract illnesses, laboratory diagnosis is necessary for confirmation. common ways of collecting samples for testing include nasal and throat swabs. samples may be taken from the lower respiratory tract if infection has cleared the upper but not lower respiratory tract. influenza testing is recommended for anyone hospitalized with symptoms resembling influenza during flu season or who is connected to an influenza case. for severe cases, earlier diagnosis improves patient outcome. diagnostic methods that can identify influenza include viral cultures, antibody- and antigen-detecting tests, and nucleic acid-based tests. viruses can be grown in a culture of mammalian cells or embryonated eggs for 3–10 days to monitor cytopathic effect. final confirmation can then be done via antibody staining, hemadsorption using red blood cells, or immunofluorescence microscopy. shell vial cultures, which can identify infection via immunostaining before a cytopathic effect appears, are more sensitive than traditional cultures with results in 1–3 days. cultures can be used to characterize novel viruses, observe sensitivity to antiviral drugs, and monitor antigenic drift, but they are relatively slow and require specialized skills and equipment. serological assays can be used to detect an antibody response to influenza after natural infection or vaccination. common serological assays include hemagglutination inhibition assays that detect ha-specific antibodies, virus neutralization assays that check whether antibodies have neutralized the virus, and enzyme-linked immunoabsorbant assays. these methods tend to be relatively inexpensive and fast but are less reliable than nucleic-acid based tests. direct fluorescent or immunofluorescent antibody (dfa/ifa) tests involve staining respiratory epithelial cells in samples with fluorescently-labeled influenza-specific antibodies, followed by examination under a fluorescent microscope. they can differentiate between iav and ibv but can't subtype iav. rapid influenza diagnostic tests (ridts) are a simple way of obtaining assay results, are low cost, and produce results quickly, at less than 30 minutes, so they are commonly used, but they can't distinguish between iav and ibv or between iav subtypes and are not as sensitive as nucleic-acid based tests. nucleic acid-based tests (nats) amplify and detect viral nucleic acid. most of these tests take a few hours, but rapid molecular assays are as fast as ridts. among nats, reverse transcription polymerase chain reaction (rt-pcr) is the most traditional and considered the gold standard for diagnosing influenza because it is fast and can subtype iav, but it is relatively expensive and more prone to false-positives than cultures. other nats that have been used include loop-mediated isothermal amplification-based assays, simple amplification-based assays, and nucleic acid sequence-based amplification. nucleic acid sequencing methods can identify infection by obtaining the nucleic acid sequence of viral samples to identify the virus and antiviral drug resistance. the traditional method is sanger sequencing, but it has been largely replaced by next-generation methods that have greater sequencing speed and throughput. treatment main article: influenza treatment treatment of influenza in cases of mild or moderate illness is supportive and includes anti-fever medications such as acetaminophen and ibuprofen, adequate fluid intake to avoid dehydration, and resting at home. cough drops and throat sprays may be beneficial for sore throat. it is recommended to avoid alcohol and tobacco use while sick with the flu. aspirin is not recommended to treat influenza in children due to an elevated risk of developing reye syndrome. corticosteroids likewise are not recommended except when treating septic shock or an underlying medical condition, such as chronic obstructive pulmonary disease or asthma exacerbation, since they are associated with increased mortality. if a secondary bacterial infection occurs, then treatment with antibiotics may be necessary. antivirals antiviral drugs drugroute of administrationapproved age of use oseltamiviroralat least two weeks old zanamivirinhalationat least five years old peramivirintravenous injectionat least 18 years old laninamivirinhalation40 milligrams (mg) dose for people at least 10 years old, 20 mg for those under 10 baloxavir marboxiloralat least 12 years old antiviral drugs are primarily used to treat severely ill patients, especially those with compromised immune systems. antivirals are most effective when started in the first 48 hours after symptoms appear. later administration may still be beneficial for those who have underlying immune defects, those with more severe symptoms, or those who have a higher risk of developing complications if these individuals are still shedding the virus. antiviral treatment is also recommended if a person is hospitalized with suspected influenza instead of waiting for test results to return and if symptoms are worsening. most antiviral drugs against influenza fall into two categories: neuraminidase (na) inhibitors and m2 inhibitors. baloxavir marboxil is a notable exception, which targets the endonuclease activity of the viral rna polymerase and can be used as an alternative to na and m2 inhibitors for iav and ibv. na inhibitors target the enzymatic activity of na receptors, mimicking the binding of sialic acid in the active site of na on iav and ibv virions so that viral release from infected cells and the rate of viral replication are impaired. na inhibitors include oseltamivir, which is consumed orally in a prodrug form and converted to its active form in the liver, and zanamivir, which is a powder that is inhaled nasally. oseltamivir and zanamivir are effective for prophylaxis and post-exposure prophylaxis, and research overall indicates that na inhibitors are effective at reducing rates of complications, hospitalization, and mortality and the duration of illness. additionally, the earlier na inhibitors are provided, the better the outcome, though late administration can still be beneficial in severe cases. other na inhibitors include laninamivir and peramivir, the latter of which can be used as an alternative to oseltamivir for people who cannot tolerate or absorb it. the adamantanes amantadine and rimantadine are orally administered drugs that block the influenza virus's m2 ion channel, preventing viral uncoating. these drugs are only functional against iav but are no longer recommended for use because of widespread resistance to them among iavs. adamantane resistance first emerged in h3n2 in 2003, becoming worldwide by 2008. oseltamivir resistance is no longer widespread because the 2009 pandemic h1n1 strain (h1n1 pdm09), which is resistant to adamantanes, seemingly replaced resistant strains in circulation. since the 2009 pandemic, oseltamivir resistance has mainly been observed in patients undergoing therapy, especially the immunocompromised and young children. oseltamivir resistance is usually reported in h1n1, but has been reported in h3n2 and ibvs less commonly. because of this, oseltamivir is recommended as the first drug of choice for immunocompetent people, whereas for the immunocompromised, oseltamivir is recommended against h3n2 and ibv and zanamivir against h1n1 pdm09. zanamivir resistance is observed less frequently, and resistance to peramivir and baloxavir marboxil is possible. prognosis in healthy individuals, influenza infection is usually self-limiting and rarely fatal. symptoms usually last for 2–8 days. influenza can cause people to miss work or school, and it is associated with decreased job performance and, in older adults, reduced independence. fatigue and malaise may last for several weeks after recovery, and healthy adults may experience pulmonary abnormalities that can take several weeks to resolve. complications and mortality primarily occur in high-risk populations and those who are hospitalized. severe disease and mortality are usually attributable to pneumonia from the primary viral infection or a secondary bacterial infection, which can progress to ards. other respiratory complications that may occur include sinusitis, bronchitis, bronchiolitis, excess fluid buildup in the lungs, and exacerbation of chronic bronchitis and asthma. middle ear infection and croup may occur, most commonly in children. secondary s. aureus infection has been observed, primarily in children, to cause toxic shock syndrome after influenza, with hypotension, fever, and reddening and peeling of the skin. complications affecting the cardiovascular system are rare and include pericarditis, fulminant myocarditis with a fast, slow, or irregular heartbeat, and exacerbation of pre-existing cardiovascular disease. inflammation or swelling of muscles accompanied by muscle tissue breaking down occurs rarely, usually in children, which presents as extreme tenderness and muscle pain in the legs and a reluctance to walk for 2–3 days. influenza can affect pregnancy, including causing smaller neonatal size, increased risk of premature birth, and an increased risk of child death shortly before or after birth. neurological complications have been associated with influenza on rare occasions, including aseptic meningitis, encephalitis, disseminated encephalomyelitis, transverse myelitis, and guillain–barré syndrome. additionally, febrile seizures and reye syndrome can occur, most commonly in children. influenza-associated encephalopathy can occur directly from central nervous system infection from the presence of the virus in blood and presents as suddent onset of fever with convulsions, followed by rapid progression to coma. an atypical form of