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Johns Hopkins Symptoms and Remedies

Johns Hopkins Medicine

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Influenza

What is it?

Influenza, commonly known as the flu, is a highly contagious viral infection of the respiratory tract. Often occurring as an epidemic, the flu results from three kinds of Orthomyxoviruses: influenzae types A, B, and C. Type A viruses tend to be the most virulent, and constantly mutate into new strains, making permanent immunization against them difficult. Type A influenza is most often responsible for large epidemics. The type B virus, generally a less severe variety, mutates occasionally, causing smaller, more localized outbreaks. Type C, which causes only mild illness resembling a common cold, is a very stable virus. During an initial bout with a type C infection, the body produces antibodies that confer immunity against future infections. Symptoms of all types of influenza usually appear following an incubation period of one to four days after initial exposure, and run their course over a period of seven to 10 days. The elderly, the very young, and the chronically ill are at increased risk of potentially serious complications such as bacterial bronchitis and pneumonia.

What Causes It?

  • The virus is spread by infected people coughing or sneezing. Most often, outbreaks occur in winter, when people tend to remain inside and are in close proximity to one another.

Prevention

  • A yearly flu vaccination is recommended for people at high risk of developing complications, including those with chronic heart or kidney disease; chronic lung disease (including asthma, emphysema, chronic bronchitis, tuberculosis, or cystic fibrosis); diabetes mellitus or other chronic metabolic disorders; severe anemia; and depressed immunity due to diseases (such as AIDS) or medical treatments (such as chemotherapy for cancer).Women who will be in the 2nd or 3rd trimester of pregnancy during influenza season, health-care workers, and people over age 50 or who live in a nursing facility are also at heightened risk. The vaccine should be administered before the start of flu season, between October 1 and the middle of November.
  • Avoid close contact with those who are infected.
  • Amantadine or rimantadine may be prescribed by a physician during local influenza epidemics, to be taken daily if high-risk patients have not been immunized for that year.

Diagnosis

  • Diagnosis is usually self-evident from symptoms; however, rapid diagnostic tests as well as a viral culture can be very useful.

How to Treat It

  • Get plenty of bed rest, preferably in a warm, well-ventilated room.
  • Take over-the-counter pain relievers to ease aches and reduce fever. (Give acetaminophen, not aspirin, to children.)
  • Drink plenty of fluids to keep mucus secretions thin and easy to expel.
  • Drink warm liquids or gargle with salt water to alleviate a sore throat.
  • A cool-mist humidifier may help to thin mucus.
  • For the elderly or those with a serious chronic illness, the antiviral drugs amantadine or rimantadine may help reduce the severity of symptoms from type A infections, if administered within 24 hours of onset. Zanamivir or oseltamivir can be used to treat type A and type B infections.

When to Call a Doctor

  • See a doctor if flu symptoms do not improve after a week to 10 days.
  • Those with any of the conditions that carry a high risk of complications (see Prevention) should consult a doctor immediately if flu exacerbates an underlying illness.