WHAT IS INFLUENZA AND SYMPTOMS OF INFLUENZA HOW IT SPREADS AND THE SEASON

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The symptoms of influenza illness include the abrupt onset of constitutional and respiratory signs and symptoms such as fever, muscle aches, headache, malaise, nonproductive cough, sore throat, and runny nose. Among children symptoms of influenza can also be ear infection, nausea, and vomiting. The Influenza viruses are spread from person to person primarily through large-particle respiratory droplet transmission as when an infected person coughs or sneezes near a susceptible person

H1N1 Flu and Being Old




Influenza A and B are the two types of influenza viruses that cause epidemics in people. Transmission via large-particle influenza droplets requires close contact between source and recipient persons, because droplets do not remain suspended in the air and generally travel only a short distance through the air. Contact with respiratory-droplet contaminated surfaces is another possible source of transmission. Airborne transmission also is thought to be possible.



The typical incubation period for influenza is 1–4 days (average 2 days). Adults can be infectious from the day before symptoms begin through approximately 5 days after illness onset. Young children also might shed virus several days before illness onset, and children can be infectious for 10 days or more after onset of symptoms. Severely immuno-compromised persons can shed virus for weeks or months.



In the United States, annual epidemics of influenza typically occur during the fall or winter months, but the peak of influenza activity can occur as late as April or May . Uncomplicated influenza illness typically resolves after 3–7 days for the majority of persons, although cough and malaise can persist for more than 2 weeks.



However, influenza virus infections can cause primary influenza viral pneumonia; exacerbate underlying medical conditions (e.g., lung or heart disease); lead to secondary bacterial pneumonia, sinusitis, or ear infection; or contribute to coinfections with other viruses or bacteria. Young children with influenza virus infection might have initial symptoms mimicking bacterial blood infection with high fevers, and febrile seizures have been reported in 6% to 20% of children hospitalized with influenza virus infection.



Respiratory illnesses caused by influenza virus infection are difficult to distinguish from illnesses caused by other respiratory germs on the basis of signs and symptoms alone.



Annual vaccination against influenza is recommended for:

all persons, including school-aged children, who want to reduce the risk of becoming ill with influenza or of transmitting influenza to others

all children aged 6–59 months (i.e., 6 months to 4 years)

all persons aged 50 years and older

children and adolescents aged 6 months to 18 years receiving long-term aspirin therapy who therefore might be at risk for experiencing Reye syndrome after influenza virus infection

women who will be pregnant during the influenza season

adults and children who have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological or metabolic disorders including diabetes mellitus

adults and children who have immunosuppression including immunosuppression caused by medications or by human immunodeficiency virus

adults and children who have any condition (e.g., cognitive dysfunction, spinal cord injuries, seizure disorders, or other neuromuscular disorders) that can compromise respiratory function or the handling of respiratory secretions or that can increase the risk for aspiration

residents of nursing homes and other chronic-care facilities

health-care personnel

healthy household contacts (including children) and caregivers of children aged less 5 years and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged less than 6 months

healthy household contacts (including children) and caregivers of persons with medical conditions that put them at higher risk for severe complications from influenza.

Seasonal Flu




Although yearly vaccination with the flu vaccine is the primary strategy for preventing complications of influenza virus infections, antiviral medications with activity against influenza viruses can be effective for the prevention and treatment of influenza. Two licensed influenza antiviral agents are recommended for use in the United States during the 2007-08 influenza season: oseltamivir and zanamivir. These are chemically related antiviral medications known as neuraminidase inhibitors that have activity against both influenza A and B viruses.

Oseltamivir (Tamiflu) is approved for treatment of persons aged 1 year and older and is licensed for use as chemoprophylaxis in persons aged 1 year and older.

Zanamivir (Relenza) is approved for treatment of persons aged 7 years and older and is licensed for use as chemoprophylaxis in persons aged 5 years and older.

Recommended Antiviral Agents for Seasonal Influenza for 2007-2008