2009 H1N1 influenza virus

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The 2009 H1N1 influenza virus, commonly referred to as swine flu, is an influenza A virus first discovered in April 2009, which contains human, porcine and avian genes.[1] Those infected with the H1N1 virus report symptoms similar to those observed in most influenza A viral infections, namely fever, cough, sore throat, body aches, headache, chills and fatigue, and a significant fraction of those afflicted report diarrhea and vomiting. It may cause severe illness and death. Although seasonal influenza normally differentially affects certain populations, including young children, people over 65 years of age, pregnant women, and the chronically ill, population related risks are yet to be determined for this virus. The virus is contagious so common health care precautions should be taken to avoid contracting this flu.

Epidemiology

The 2009 H1N1 influenza virus is a novel H1N1 strain.[2] Although in the prior 2007-2008 season, H1N1 was about a third of all cases[3], starting in April 2009 a H1N1 strain emerged that was initially untypeable. The 2009 novel H1N1 influenza virus contains genes normally found in North American swine as well as two genes found in European and Asian swine and has been called a triple-reassortant of genes.[2][4]

Prevention

General good health practices should be taken to avoid this and other illnesses. Most importantly, wash your hands often, and avoid sick persons and unnecessarily touching surfaces. Stay fit by eating a well-balanced, nutritious diet, drink plenty of water, get sufficient sleep each day, and exercise. The use of antibacterial soaps are no better than regular soaps at removing this virus from your hands.

Once infected, one may reduce the spread of the flu in a number of simple ways.

Hygiene

  • Do not cough or sneeze into your hands directly, but cover your nose and mouth with a tissue (or shirt sleeve - the current suggestion is, in the absence of a tissue, cough or sneeze into the crux of your elbow rather than your hands).
  • Throw the tissue away directly, without setting it on other surfaces, such as desk tops or kitchen counters.
  • Wash your hands often with soap and water, especially after you cough or sneeze.
  • Avoid touching your eyes, nose or mouth, and wash your hands afterwards.
  • Stay home for 7 days after symptoms begin or you have been symptom free for 24 hours.
  • Avoid close contact with sick people.
  • Avoid shopping after becoming ill. Buy at least a one week supply of medications, tissues, soaps, and so on.

Medications and Infectivity

The antiviral drugs oseltamivir and/or zanamivir are recommended by the Centers for Disease Control for the treatment and/or prevention of 2009 H1N1. These antiviral drugs inhibit the reproductive cycle of the virus, thereby ameliorating the severity and length of illness. Although the period of infectivity for a person with H1N1 has yet to be determined, persons with influenza are typically contagious beginning 1 day before the onset of symptoms and 7 days after symptom onset. Childrem may be contagious for a longer time period.

Food, Water and Recreation

One can not become infected by the swine flu from eating properly cooked pork products. Based on previous studies of the H5N1 avian flu, it is expected that chlorine levels used in municipal water supplies should be sufficient to kill the H1N1 virus. Likewise, properly treated water at swimming pools, spas, water parks, interactive fountains, and other treated recreational water venues should be free of the virus. The virus is contagious so common health care precautions should be taken to avoid contracting this flu.

Seeking Medical Attention

One should seek immediate medical attention when patients experience any of the following warning signs:

In Adults or Children:

  • difficult or rapid breathing,
  • Chest/Abdominal pain or pressure
  • Sudden dizziness or confusion
  • Severe or persistent vomiting

Additional warning signs in children:

  • Bluish or gray skin color
  • Insufficient fluid intact
  • Not waking up or interacting
  • Being so irritable that the child does not want to be held
  • Flu-like symptoms improve but then return with fever and worse cough
  • Fever with a rash

Treatment

Peramivir is an investigational intravenous neuraminidase inhibitor that can be used.[5]

Complications

Various pulmonary complications may occur including pulmonary embolism.[6]

References

  1. NCBI list of deposited sequences for 2009 H1N1
  2. 2.0 2.1 Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team. Dawood FS, Jain S, Finelli L, Shaw MW, Lindstrom S et al. (2009). "Emergence of a novel swine-origin influenza A (H1N1) virus in humans.". N Engl J Med 360 (25): 2605-15. DOI:10.1056/NEJMoa0903810. PMID 19423869. Research Blogging.
  3. 2007-08 U.S. INFLUENZA SEASON SUMMARY, Centers for Disease Control and Prevention
  4. Swine Flu & You
  5. Birnkrant D, Cox E (2009). "The Emergency Use Authorization of Peramivir for Treatment of 2009 H1N1 Influenza.". N Engl J Med. DOI:10.1056/NEJMp0910479. PMID 19884645. Research Blogging.
  6. Agarwal PP et al (2009) Chest Radiographic and CT Findings in Novel Swine-Origin Influenza A (H1N1) Virus (S-OIV) Infection American Journal of Radiology