1. Swine Flu (H1N1) FAQ Slideshow Pictures
2. Strep or Sore Throat Slideshow Pictures
3. Flu Fighter Foods Slideshow Pictures

Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• Swine flu (H1N1 influenza virus) facts
• What is the swine flu (novel H1N1 influenza A swine flu)?
• What causes swine flu (H1N1)?
• Why is swine flu (H1N1) now infecting humans?
• What are the symptoms of swine flu (H1N1)?
• How is swine flu (H1N1) diagnosed?
• What is the treatment for swine flu (H1N1)?
• What is the history of swine flu (H1N1)?
• What are the risk factors for swine flu (H1N1)?
• Can novel H1N1 swine flu be prevented with a vaccine?
• Can H1N1 be prevented if the H1N1 flu vaccine (or other flu strain vaccine) is not readily available?
• Is swine flu (H1N1) a cause of an epidemic or pandemic in the 2009-2010 flu season?
• What is the prognosis (outlook) and complications for patients who get swine flu (H1N1)?
• Where can I find more information about swine flu (H1N1)?
• Swine Flu (H1N1) FAQ Slideshow Pictures
• Pictures of Strep or Sore Throat - Slideshow
• Flu Fighter Foods Slideshow Pictures
• Patient Comments: Swine Flu - Symptoms and Signs
• Patient Comments: Swine Flu - Concerns
• Swine Flu Index

Yes. An epidemic is defined as an outbreak of a contagious disease that is rapid and widespread, affecting many individuals at the same time. The swine flu outbreak in Mexico fit this definition. A pandemic is an epidemic that becomes so widespread that it affects a region, continent, or the world. As of June 11, 2009, WHO officials determined that H1N1 2009 influenza A swine flu reached WHO level 6 criteria (person-to-person transmission in two separate WHO-determined world regions) and declared the first flu pandemic in 41 years. The H1N1 flu reached over 200 different countries on every continent except Antarctica in the 2009-2010 flu season; fortunately, the severity of the disease has not increased.

In general, the majority (about 90%-95%) of people who get the disease feel terrible (see symptoms) but recover with no problems, as seen in patients in both Mexico, the U.S., and many other countries.

People with suppressed immune systems historically have worse outcomes than uncompromised individuals; investigators suspect that as swine flu (H1N1) spreads, the mortality rates may rise and be high in this population. Current data suggest that pregnant individuals, children under 2 years of age, young adults, and individuals with any immune compromise or debilitation are likely to have a worse prognosis. Complications of H1N1 may resemble severe viral pneumonia or the SARS (severe acute respiratory syndrome caused by a coronavirus strain) outbreak in 2002-2003 in which the disease spread to about 10 countries with over 7,000 cases, caused over 700 deaths, and had a 10% mortality rate. At the beginning of the pandemic, the numbers of people with flu-like illness were higher than usual and the illness initially affected a much younger population than the conventional flu. As the pandemic progressed, more young children became infected than usual, but the mortality statistics became more similar to the conventional flu mortality rate, with an older population (especially ages 50-64) having the highest death rate. The best news about the H1N1 swine flu is that the majority of people worldwide who have caught the H1N1 flu recover without medical treatment and have an excellent prognosis.