Everything You Need to Know About the Common Cold

By John Rindfleisch, Clinton FD Chief

 He’s baaaaaaaaaaaack. He’s going around town, sneaking into everyone’s home leaving behind something we do not want. He’s that little green slimy mucus guy you see on the TV commercials. You’re catching him from your spouse, kids, or the neighbor. How do we keep him out? What can you do if he’s already there? Let’s go over some things that will keep him out or make him move on faster. First, here is how he makes his way past your immune system. The nose contains shelf-like structures called turbinates, which help trap particles entering the nasal passages. Inhaled particles are deposited in the nose, and then transported to the back of the throat in 10-15 minutes. Cold viruses are believed to be carried to the back of the throat where they are deposited near the adenoid. The adenoid is a lymph gland structure that contains cells to which cold viruses attach.

A common cold is an illness caused by a virus infection located in the nose. Colds also involve the sinuses, ears, and bronchial tubes. The symptoms of a common cold include sneezing, runny nose, nasal obstruction, sore or scratchy throat, cough, hoarseness, and mild general symptoms like headache, feverishness, chilliness, and not feeling well in general.

Colds last on average for one week. Mild colds may last only two or three days while severe colds may last for up to two weeks. A cold is a milder illness than influenza. Influenza typically causes fever, muscle aches, and a more severe cough. However, mild cases of influenza are similar to colds. Adults average two to three colds per year and children six to ten, depending on their age and exposure. Children’s noses are the major source of cold viruses. There are over 100 different cold viruses. Rhinoviruses are the most important and cause at least one-half of colds.

Cold viruses can only multiply when they are inside of living cells. When on an environmental surface, cold viruses cannot multiply. However, they are still infectious if they are transported from an environmental site into the nose.

Cold viruses live only in the noses of humans and not in animals except chimpanzees and other higher primates. A cold virus is deposited into the front of the nasal passages by contaminated fingers or by droplets from coughs and sneezes.

Small doses of a virus are sufficient to produce an infection. The virus is then transported to the back of the nose and onto the adenoid area by the nose itself! The virus then attaches to a receptor, which is located on the surface of nasal cells.

The receptor fits into a docking port on the surface of the virus. Large amounts of virus receptors are present on cells of the adenoid. After attachment to the receptor, a virus is taken into the cell where it starts an infection. New virus particles are produced in the infected cell. The infected cell eventually dies and ruptures, releasing newly made cold viruses to infect other cells in the nose and start the process over again. The virus is much smaller than the cell. Small doses of a virus, when introduced into the nose are sufficient to reliably produce infection. From the time a cold virus enters the nose, it takes 8-12 hours for the viral reproductive cycle to be completed and for a new cold virus to be released in the nasal secretions. This interval is called the incubation period. Cold symptoms can also begin shortly after a virus is first produced in the nose.

The time from the beginning of the infection to the peak of symptoms is typically 36-72 hours. Cold viruses infect only a relatively small portion of the cells lining the nose. Cold symptoms are due mainly to the body’s response to the infection.

When a nasal cell is infected by a cold virus, the body responds by activating parts of the immune system and some nervous system reflexes. The immune system contains a variety of natural substances called inflammatory mediators. Inflammatory mediators help protect the body from infection and other harmful events. Some inflammatory mediators are released when a cold virus infects nasal cells. The names of some inflammatory mediators involved in colds include histamine, kinins, interleukins, and the prostaglandins. When activated by a cold virus infection, inflammatory mediators cause dilatation and leakage of blood vessels and mucus gland secretion. Inflammatory mediators also activate sneeze and cough reflexes and stimulate pain nerve fibers.

These events are what lead to the symptoms of a cold. The activity of the inflammatory mediators is not necessary for recovery from a cold virus infection. Twenty-five percent of people who acquire a cold virus infection do not develop symptoms. People without cold symptoms recover from the infection as well as those who have symptoms.

The individual symptoms of a cold are caused by the action of particular inflammatory mediators, although there is some overlapping. This has important implications for developing and selecting effective cold treatments.

So now that we know all the scientific stuff about how and why we get colds, what can we do to prevent them? Even if they haven’t found a cure for colds, researchers have learned plenty about how cold viruses spread. Coughing and sneezing are still the top ways of giving someone else your cold. People can breathe in the germs from your cough or sneeze. Rhinoviruses can also be spread by touching contaminated surfaces, shaking hands, and other personal contact. If you get cold viruses on your fingers, you might touch your nose or eyes — the two places the virus can most easily enter your body. Rhinoviruses can survive on doorknobs, table tops, shopping cart handles, and other surfaces for 24 hours or more. The most obvious way to prevent picking up a cold, then, is keeping your fingers out of your eyes and nose. Most of us rub our eyes or touch our noses often without thinking. Number one for prevention is to wash your hands frequently. Rub your hands together with soap and water, scrubbing the fronts and backs and in between your fingers while singing “Happy Birthday” twice. That should send those nasty germs swirling down the drain. Hand sanitizer with at least 60% alcohol is a great backup plan if soap and water aren’t available. Remember that hand sanitizers have an expiration date on them and should be replaced to get maximum protection. Regularly cleaning and disinfecting surfaces that are touched a lot can also help slow the spread of germs. Use a household disinfectant to clean countertops, desks, doorknobs, handles, phones, and toys. There are many over the counter items to buy once you are infected. You need to talk to your doctor since many of these products have side effects that your doc can give you advice on.

Until next week, wash your hands and stay safe