Influenza (2009 H1N1)

By Clarke, Rachael

What is 2009 H1N1 influenza?

The 2009 H1N1 influenza virus (or flu) is a contagious viral respiratory tract infection. 2009 H1N1 flu is characterized by the abrupt onset of symptoms similar to seasonal flu, such as fever, muscle aches, and sore throat.

This virus was originally referred to as swine flu, because many of its genes resemble a virus that normally occurs in pigs. Additional research has shown, however, that 2009 H1N1 flu is made up of swine flu genes as well as avian and human flu genes.

The World Health Organization (WHO) declared 2009 H1N1 flu a global pandemic in June 2009. As of September 20, 2009, the WHO estimated that 2009 H1N1 is widespread in the U.S., Canada, Mexico, parts of South America, Ireland, New Zealand, Thailand, Australia, and Cambodia. The virus also has spread regionally throughout Brazil, India, and Indonesia, and locally throughout Europe.

Although the virus has spread globally, most individuals in the U.S. who have contracted the virus have fully recovered without medical treatment.

Facts about 2009 H1N1 influenza:

  • Unlike seasonal influenza, 2009 H1N1 infections have occurred mainly in younger people. Research suggests that older adults may have some degree of resistance to the virus, potentially due to previous exposure to a related influenza A H1N1 virus that circulated before 1957.

  • Like seasonal flu, 2009 H1N1 flu can range from mild to severe, and can be deadly in some cases. Those with chronic medical conditions are at higher risk for complications and death from H1N1. Researchers believe that some people at high risk for seasonal flu complications are also at higher risk for complications from 2009 H1N1 flu.

What causes 2009 H1N1 influenza?

As with seasonal flu, 2009 H1N1 flu is generally passed from person to person by airborne transmission (for example, sneezing or coughing). But, the virus can also live for a short time on objects--such as doorknobs, pens, pencils, keyboards, telephone receivers, and eating or drinking utensils. Therefore, it may also be spread by touching something that has been handled by someone infected with the virus and then touching your own mouth, nose, or eyes.

People who have 2009 H1N1 flu are considered contagious starting one day before they show symptoms and for up to seven or more days after the illness starts. Children and individuals with weakened a immune system may be contagious for an even longer period of time. 2009 H1N1 flu is not spread through food. Eating well-cooked pork and pork products does not pose any risk for infection from this virus.

What are the symptoms of 2009 H1N1 influenza?

2009 H1N1 flu symptoms are similar to the most common symptoms of the seasonal flu. However, each individual may experience symptoms differently. Influenza is called a respiratory disease, but the whole body seems to suffer when a person is infected. People who contract 2009 H1N1 flu usually become acutely ill with several, or all, of the following symptoms:

  • Fever

  • Headache

  • Runny or stuffy nose

  • Cough

  • Aches and pains

  • Fatigue

  • Sore throat

  • Chills

Some people may also experience diarrhea and vomiting. Children do not always display these symptoms, and may experience difficulty breathing and be less active than normal.

If you experience one or more of the following symptoms, seek emergency medical care immediately:

  • Difficulty breathing

  • Pressure or pain in the stomach or chest

  • Persistent or severe vomiting

  • Confusion

  • Dizziness

  • Flu symptoms that improve and later return with fever and worse cough

Treatment for 2009 H1N1 influenza:

Specific treatment for influenza can vary, and will be determined by your physician based on:

  • Your age, overall health, and medical history

  • Extent of the virus

  • Severity of symptoms

  • Tolerance for specific medications

  • Expectations for the course of the disease

  • Your opinion or preference

The goal of treatment for 2009 H1N1 influenza is to help prevent or decrease the severity of symptoms. Talk with your doctor about what actions are best for you to take.

At this time, the Centers for Disease Control and Prevention (CDC) recommends the antiviral drugs oseltamivir (brand name Tamiflu) or zanamivir (brand name Relenza) to treat people who are hospitalized for 2009 H1N1 or seasonal flu, those who also have more severe symptoms such as a lower respiratory tract infection, or people who are at high risk for complications.

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