Several weeks ago I got a flu shot. Having rolled up my sleeve in the hope of preventing the flu, I was dismayed to awake with my throat so swollen that the simple tasks of swallowing or talking brought pain. I went to work and muddled miserably through the day. Once home, I tried to escape the curse of the microscopic rascal by drinking brandy — erroneously thinking the alcohol would kill the virus infecting my throat — and swallowing antihistamine and Tylenol. But alas, I awoke with my sinuses full and my concentration off. I struggled through an e-mail to coworkers announcing that I was home sick and faced the prospect of Dr. Phil and daytime television.
After running through endless tissues, cold medications and orange juice, I decided to write about the virus that triggered the immune system reaction that is partly responsible for the recent silence of this blog.
More than 200 viruses are known to cause the symptoms of the common cold, the most common infectious disease in the United States and the number-one reason children visit the doctor. The cold virus is responsible for keeping more people out of work and school than any other illness. Most adults will have two to four colds a year and children may have as many as eight to ten.
When I returned to work my coworkers asked me if I had the flu. I had to say that I had a common head cold. I should have said that I had a contagious case of rhinorrheaI, or a runny nose because although I felt tired and my head ached, the illness was centered in my nose.
Once infected with a cold, nasal secretions are teeming with cold viruses. We catch a cold by breathing in virus particles that are spread through the air by an infected person’s sneezes or coughs. Virus particles can travel up to 12 feet (3.7 meters) through the air when someone with a cold coughs or sneezes. Cold viruses are also spread when we touch our nose, eyes, or mouth after touching something contaminated by infected nasal secretions. Small doses of virus (1-30 particles) are sufficient to produce infection.
The cold virus is deposited into the front of nasal passages and then transported to the back of the nose where it attaches to a cell. Much smaller than the cell, the virus injects its genetic material into the cell and tricks it into producing virus. The infected nasal cell ruptures and dies, releasing newly made cold virus to infect other cells in the nose and start the process over again.
From the time a cold virus enters the nose, it takes 8-12 hours for the viral reproductive cycle to be completed and for new cold virus to be released in nasal secretions. Cold symptoms can begin shortly after virus is first produced in the nose. Colds are most contagious during the first 2 to 4 days after symptoms appear, and may be contagious for up to 3 weeks. Usually irritation in the nose or a scratchy feeling in the throat is the first sign of a cold, followed within hours by sneezing and a watery nasal discharge.
Many people use the term ‘flu’ to describe any kind of respiratory or winter illness they get, which is understandable because cold and flu share similar symptoms, and both come during cold and flu season. Although influenza viruses can cause symptoms of the common cold, flu is a more aggressive virus. You may hear a coworker say, I had the flu, but I came to work anyway. It is unlikely that person has influenza, because it is highly unlikely he or she would have been able to come to work. Chances are they really have a contagious case of rhinorrheaI, not the flu.
The symptoms we get during a viral illness are the body’s attempt to get rid of the virus. Sneezing ejects the virus from the nose, cough from the lungs and throat, vomiting from the stomach, and diarrhea from the intestines. Fever makes it difficult for the virus to reproduce.
The common cold is centered in the nose. Rhinoviruses, which mean “nose viruses”, are the most common cause of colds. Rhinoviruses grow best at temperatures of about 91 degrees Fahrenheit, the temperature inside the human nose. More than 110 different rhinovirus types can infiltrate the protective lining of the nose and throat causing headache, cough, postnasal drip, burning eyes, muscle aches, or a decreased appetite. The most prominent symptoms are in the nose.
With the flu, we are sick all over. A single family of viruses — the influenza viruses — cause the flu. Typically, the flu begins abruptly, with a fever in the 102 to 106 degree range (with adults on the lower end of the spectrum), chills, lack of energy, body aches and sometimes dizziness or vomiting. The fever usually lasts for a day or two, but can last five days.
Somewhere between day 2 and day 4 of the illness, the “whole body” symptoms begin to subside, and respiratory symptoms begin to increase. The virus can settle anywhere in the respiratory tract, producing symptoms of a cold, croup, sore throat, bronchiolitis, ear infection, and/or pneumonia. Sometimes there is a second wave of fever. The cough and tiredness usually lasts for weeks after the rest of the illness is over.
The 1918 worldwide flu epidemic infected over 500 million people, and killed 50 million. In the United States, more than 500,000 died. The 1918 flu epidemic killed more people in less time than any disease in modern history. It ranks with the Black Death of the 14th Century as one of the few events in recorded history to reduce the population of the earth by as much as one percent. Even today, more than 36,000 people in the United States die from the flu each year — primarily those who are weak from advanced age or a major illness.
The flu is preventable. In any given year, two or three different strains of influenza virus cause most of the flu around the world. Scientists gather extensive global data and formulate a vaccine for the strains anticipated to be the major problems in the coming winter. While the prediction is usually accurate, sometimes new, unanticipated strains arise.
Three strains including Influenza A H1N1 and H3N2 and Influenza B have been reported in 2006-2007. The names reflect the areas where the viruses were first identified. For example, a virus identified by the Baylor Flu Center in October 1991 was named A/Texas
While vaccines have progressed in flu prevention, the closest we’ve seen to a cure for the common cold is chicken soup and the love and hugs of family and friends.
Air that’s dry – indoors or out – can lower our resistance to infection by the viruses that cause colds. And so can smoking cigarettes or being around someone who’s smoking. There is no evidence that you can get a cold from exposure to cold weather or from getting chilled or overheated. There is also no evidence that your chances of getting a cold are related to factors such as exercise, diet, or enlarged tonsils or adenoids. Conversely, research suggests that psychological stress and allergic diseases affecting your nose or throat may have an impact on your chances of getting infected by cold viruses because with reduced immunity, dormant infections are more likely to develop into full-blown colds.
In the words of Atul Gawande, “So what does work for colds? Drinking plenty of liquids keeps mucus flowing out of the body and carrying viruses with it. Trials show that over-the-counter combination decongestant/antihistamines do help relieve nasal congestion and post-nasal drip. And when suffering from a bout of miracle-cure claims, try a healthy dose of skepticism.”
Cold and Flu Differences: http://www.drgreene.com/21_577.html
Chicken soup is medicine, U.S. scientists confirm. CNN.com: http://archives.cnn.com/2000/HEALTH/diet.fitness/10/17/chicken.soup.reut/
Common Cold. http://www.cnn.com/HEALTH/library/DS/00056.html
Common cold Index. National Institute of Allergy and Infection Diseases (2006): http://www3.niaid.nih.gov/healthscience/healthtopics/colds/default.htm
The Flu Goes to Work http://health.msn.com/guides/coldandflu/articlepage.aspx?cp-documentid=100118517
Flu FAQ 2006-2007 from Baylor college of Medicine (November 8, 2006) https://www.bcm.edu/news/item.cfm?NewsID=745
How Cold Virus Infection Occurs: http://www.commoncold.org/undrstn3.htm
Is it a Cold or the Flu? http://www.niaid.nih.gov/publications/cold/sick.pdf
Zinc may help your sniffles–but only because you really believe it will. Slate. Atul Gawande (1997): http://www.slate.com/id/2670/