Table of Contents
The Common Cold
The common cold (medically known as infectious nasopharyngitis) is the most common upper respiratory tract infection. More than 200 different viruses can cause colds. The most common cause is the rhinovirus, which is responsible for about half of all colds. Symptoms usually develop 1 - 3 days after being exposed to the virus.
A cold usually progresses in the following manner:
- It nearly always starts rapidly with throat irritation and stuffiness in the nose.
- Within hours, full-blown cold symptoms usually develop, which can include sneezing, mild sore throat, fever, minor headaches, muscle aches, and coughing.
- Fever is low-grade or absent. In small children, however, fever may be as high as 103 °F for 1 or 2 days. The fever should go down after that time, and be back to normal by the 5th day.
- Nasal discharge is usually clear and runny the first 1 - 3 days. It then thickens and becomes yellow to greenish.
- The sore throat is usually mild and lasts only about a day. A runny nose usually lasts 2 - 7 days, although coughing and nasal discharge can persist for more than 2 weeks.
The adenovirus family causes upper respiratory infections (it is one of the many viruses that cause the common cold). It also causes pneumonia, conjunctivitis, and several other diseases. A newer strain of adenovirus has resulted in several deaths.
Influenza ("The Flu")
Every year, influenza strikes millions of people worldwide. Influenza epidemics are most serious when they involve a new strain, against which most people around the world are not immune. Such global epidemics (pandemics) can rapidly infect more than one fourth of the world's population. For example, the Spanish flu in 1918 and 1919 killed an estimated 20 million people in the U.S. and Europe and 17 million people in India. With modern society's dependence on air travel, an influenza pandemic could potentially inflict catastrophic damage on human lives, and disrupt the global economy.
More recently, the new H1N1 ("Swine Flu") that emerged in Mexico in the spring of 2009 quickly became a pandemic, though it is far less severe or deadly than the Spanish flu of 1918. As of December 23, 2009, the World Health Organization estimated the total deaths from the H1N1 pandemic at 11,516 people. It is likely the actual total is somewhat larger, because not all victims are tested for H1N1 influenza. The H1N1 pandemic was declared over by the World Health Organization in August 2010. This particular influenza strain became one of the seasonal influenza viruses circulating world-wide during the 2010-2011 flu season.
Symptoms of influenza. Patients usually feel sick 1 - 2 days after exposure to the influenza (flu) virus. The flu usually involves:
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Review Date: 01/29/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine,
Harvard Medical School; Physician, Massachusetts General Hospital.
Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M.,
Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
