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 flu (influenza)?
- Flu vs. cold
- Flu vs. food poisoning
- What are the causes of the flu (influenza)?
- When does flu season begin and end?
- What are flu (influenza) symptoms in adults and in children?
- Does a child's first flu infection help to determine the patient's lifelong risk to other viruses?
- What is the incubation period for the flu?
- How long is the flu contagious, and how long does the flu last?
- How do health-care professionals diagnose the flu (influenza)?
- How does flu spread?
- What is the key to flu (influenza) prevention?
- Are there any flu shot or nasal spray vaccine side effects in adults or in children?
- How effective is the flu vaccine?
- Why should the flu (influenza) vaccine be taken every year?
- What are some flu treatments an individual can do at home (home remedies)?
- What types of doctors treat the flu?
- What medications treat the flu?
- What can people eat when they have the flu?
- 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 for patients who get the flu? What are possible complications of the flu?
- Can the flu be deadly?
- 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 people 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 (influenza) 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, sometimes with facial flushing and/or sweating),
- respiratory symptoms such as
- cough (more often in adults),
- sore throat (more often in adults),
- runny or stuffy nose (congestion, especially in children),
- muscle aches (body aches), and
- fatigue, sometimes extreme.
Although appetite loss, 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, caused more nausea, vomiting, and diarrhea than the conventional (seasonal) flu viruses. Depending upon the severity of the infection, some patients can develop swollen lymph nodes, muscle pain, shortness of breath, severe headaches, chest pain or chest discomfort, dehydration, and even death.
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.
Does a child's first flu infection help to determine the patient's lifelong risk to other viruses?
Influenza A, as mentioned previously, has hemagglutinin on the viral surface. The viral hemagglutinins have at least 18 types, but these types are broken into two main influenza A categories. For example, one of the two main categories includes human H1, H2, and avian H5 viruses while the other major category includes human H3 and avian H7 viruses. Researchers in 2016 at UCLA and the University of. Arizona discovered that if you were exposed to one of these groups as a child, you had a much better chance of being protected against other viruses in that same group or category later in life. For example, if you are exposed to H2 as a child and then later in life to H2 or H5 viruses, you may have as high as a 75% chance of protection against those H2 and/or H5 strains, but if you are exposed to the other major category that included H3 or H7, you would be much more susceptible to these viral types. The reverse situation would be true if you were exposed as a child to H3 or H7 viruses. The researchers concluded that the immunological imprinting early in life helps determine the response (immune response) to these viral types or categories. Consequently, the first strain of flu that a person is exposed to in childhood likely determines that person's risk in the future for severity of the flu depending upon the exact category of the first viral strain that infects the child. The researchers hope to exploit these new findings in the development of new and more effective flu vaccines.
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