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.
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.
In this Article
- Flu (influenza, conventional, H1N1, H3N2, and bird flu [H5N1]) facts
- What is influenza?
- What are the causes of the flu?
- What are flu symptoms in adults and in children?
- How is the flu diagnosed?
- What is the key to flu prevention?
- Are there any flu shot or nasal spray vaccine side effects in adults or in children?
- Why should the influenza vaccine be taken every year?
- What are some flu treatments an individual can do at home?
- When should a person go to the emergency department for the flu?
- Who should receive the flu vaccine, and who has the highest risk factors? When should someone get the flu shot?
- What is the prognosis (outlook) and complications for patients who get the flu?
- What is the bird (avian) flu?
- Do antiviral agents protect people from the flu?
- Is it safe to get a flu shot that contains thimerosal?
- Where can I find additional information about the flu?
- Slideshow: Finding Relief for Your Cough
- Pictures of Natural Cold & Flu Remedies - Slideshow
- Pictures of 10 Foods to Eat When You Have the Flu - Slideshow
What are flu symptoms in adults and in children?
Typical clinical features of influenza may include
- fever (usually 100 F-103 F in adults and often even higher in children),
- respiratory symptoms such as
- cough (more often in adults),
- sore throat (more often in adults),
- runny or stuffy nose (especially in children),
- muscle aches,
- fatigue, sometimes extreme.
Although nausea, vomiting, and diarrhea can sometimes accompany influenza infection, especially in children, gastrointestinal symptoms are rarely prominent. The term "stomach flu" is a misnomer that is sometimes used to describe gastrointestinal illnesses caused by other microorganisms. H1N1 infections, however, have caused more nausea, vomiting, and diarrhea than the conventional (seasonal) flu viruses.
Most individuals who contract influenza recover in a week or two, however, others develop potentially life-threatening complications like pneumonia. In an average year, influenza is associated with about 36,000 deaths nationwide and many more hospitalizations. Flu-related complications can occur at any age; however, the elderly and people with chronic health problems are much more likely to develop serious complications after the conventional influenza infections than are younger, healthier people.
Unfortunately, people may be contagious about 24-48 hours before symptoms appear and, for those who spontaneously recover, they may shed contagious viruses for about a week.
How is the flu diagnosed?
The flu is presumptively diagnosed clinically by the patient's history of association with people known to have the disease and their symptoms listed above. Usually, a quick test (for example, nasopharyngeal swab sample) is done to see if the patient is infected with influenza A or B virus. Most of the tests can distinguish between A and B types. The test can be negative (no flu infection) or positive for types A or B. If it is positive for type A, the person could have a conventional flu strain or a potentially more aggressive strain such as H1N1. However, a new test developed by the CDC and a commercial company reportedly can detect H1N1 reliably in about one hour; the test was formerly only available to the military. In 2010, the FDA approved a commercially available test that could detect H1N1 within four hours. Most of the rapid tests are based on PCR technology that identified the genetic material of the virus.
Swine flu (H1N1) and other influenza strains like bird flu or H3N2 are definitively diagnosed by identifying the particular antigens associated with the virus strain. In general, this testing is done in a specialized laboratory and is not done by many doctors' offices or hospital laboratories unless they have purchased the newest test systems. However, doctors' offices are able to send specimens to specialized laboratories if necessary.
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