The common cold is a viral infection of the upper respiratory system, including the nose, throat, sinuses, Eustachian tubes, trachea, larynx, and bronchial tubes. Although over 200 different viruses can cause a cold, 30–50% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications. Colds, sometimes called rhinovirus or coronavirus infections, are the most common illness to strike any part of the body. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although pre-school and grade school children catch them more frequently than adolescents and adults. Repeated exposure to viruses causing colds creates partial immunity.
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise to a multi-million dollar industry in over-the-counter medications. Cold season in Kashmir usually begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased susceptibility. These include:
• Fatigue and overwork.
• Emotional stress.
• Poor nutrition.
• Living or working in crowded conditions.
Colds make the upper respiratory system less resistant to bacterial infection. Secondary bacterial infection may lead to middle ear infection, bronchitis, pneumonia, sinus infection, or strep throat. People with chronic lung disease, asthma, diabetes, or a weakened immune system are more likely to develop these complications.
Causes and symptoms
Colds are caused by more than 200 different viruses. The most common groups are rhinoviruses and coronaviruses. Different groups of viruses are more infectious at different seasons of the year, but knowing the exact virus causing the cold is not important in treatment. People with colds are contagious during the first two to four days of the infection. Colds pass from person to person in several ways. When an infected person coughs, sneezes, or speaks, tiny fluid droplets containing the virus are expelled. If other people breathe these in, the virus may establish itself in their noses and airways.
Colds may also be passed through direct contact. If a person with a cold touches his runny nose or watery eyes, then shakes hands with another person some of the virus is transferred to the uninfected person. If that person then touches his mouth, nose, or eyes, the virus is transferred to an environment where it can reproduce and cause a cold.
Finally, cold viruses can be spread through inanimate objects (door knobs, telephones, toys) that become contaminated with the virus. This is a common method of transmission in childcare centers. If a child with a cold touches his runny nose, then plays with a toy, some of the virus may be transferred to the toy. When another child plays with the toy a short time later, he may pick up some of the virus on his hands. The second child then touches his contaminated hands to his eyes, nose, or mouth and transfers some of the cold virus to himself. Once acquired, the cold virus attaches itself to the lining of the nasal passages and sinuses. This causes the infected cells to release a chemical called histamine. Histamine increases the blood flow to the infected cells, causing swelling, congestion, and increased mucus production. Within one to three days the infected person begins to show cold symptoms.
The first cold symptoms are a tickle in the throat, runny nose, and sneezing. The initial discharge from the nose is clear and thin. Later it changes to a thick yellow or greenish discharge. Most adults do not develop a fever when they catch a cold. Young children may develop a low fever of up to 102°F (38.9°C). In addition to a runny nose and fever, signs of a cold include coughing, sneezing, nasal congestion, headache, muscle ache, chills, sore throat, hoarseness, watery eyes, tiredness, and lack of appetite. The cough that accompanies a cold is usually intermittent and dry.
Most people begin to feel better four to five days after their cold symptoms become noticeable. All symptoms are generally gone within ten days, except for a dry cough that may linger for up to three weeks. Colds make people more susceptible to bacterial infections such as strep throat, middle ear infections, and sinus infections. A person whose cold does not begin to improve within a week; or who experiences chest pain, fever for more than a few days, difficulty breathing, bluish lips or fingernails, a cough that brings up greenish-yellow or grayish sputum, skin rash, swollen glands, or whitish spots on the tonsils or throat should consult a doctor to see if they have acquired a secondary bacterial infection that needs to be treated with an antibiotic.
Colds are diagnosed by observing a person’s symptoms. There are no laboratory tests readily available to detect the cold virus. However, a doctor may do a throat culture or blood test to rule out a secondary infection. Influenza is sometimes confused with a cold, but flu causes much more severe symptoms and generally a fever. Allergies to molds or pollens also can make the nose run. Allergies are usually more persistent than the common cold. An allergist can do tests to determine if the cold-like symptoms are being caused by an allergic reaction. Also, some people get a runny nose when they go outside in winter and breathe cold air. This type of runny nose is not a symptom of a cold.
There are no medicines that will cure the common cold. Given time, the body’s immune system will make antibodies to fight the infection, and the cold will be resolved without any intervention. Antibiotics are useless against a cold. However, a great deal of money is spent by pharmaceutical companies promoting products designed to relieve cold symptoms. These products usually contain antihistamines, decongestants, and/or pain relievers. Antihistamines block the action of the chemical histamine that is produced when the cold virus invades the cells lining the nasal passages. Histamine increases blood flow and causes the cells to swell.
Antihistamines are taken to relieve the symptoms of sneezing, runny nose, itchy eyes, and congestion. Side effects are dry mouth and drowsiness, especially with the first few doses. People who are driving or operating dangerous equipment should not take antihistamines. Some people have allergic reactions to antihistamines.
Nasal sprays and nose drops are other products promoted for reducing nasal congestion. These usually contain a decongestant, but the decongestant can act more quickly and strongly than ones found in pills or liquids because it is applied directly in the nose. Congestion returns after a few hours. People can become dependent on nasal sprays and nose drops. If used for a long time, users may suffer withdrawal symptoms when these products are discontinued. Nasal sprays and nose drops should not be used for more than a few days.
People react differently to different cold medications and may find some more helpful than others. A medication may be effective initially, and then lose some of its effectiveness. Children sometimes react differently than adults. Over-the-counter cold remedies should not be given to infants without consulting a doctor first.
In addition to the optional use of over the counter cold remedies, there are some self-care steps that people can take to ease their discomfort. These include:
• Drinking plenty of fluids, but avoiding acidic juices, which may irritate the throat.
• Gargling with warm salt water for a sore throat.
• Not smoking.
• Getting plenty of rest.
• Using a cool-mist room humidifier to ease congestion and sore throat.
• Rubbing Vaseline or other lubricant under the nose to prevent irritation.
Given time, the body will make antibodies to cure itself of a cold. Most colds last a week to 10 days. Most people start feeling better within four or five days. Occasionally a cold will lead to a secondary bacterial infection that causes strep throat, bronchitis, pneumonia, sinus infection, or a middle ear infection. These conditions usually clear up rapidly when treated with an antibiotic.
It is not possible to prevent colds because the viruses that cause colds are common and highly infectious. However, there are some steps individuals can take to reduce their spread. These include:
• Washing hands well and frequently, especially after touching the nose or before handling food.
• Covering the mouth and nose when sneezing.
• Disposing of used tissues properly.
• Avoiding close contact with someone who has a cold during the first two to four days of his or her infection.
• Not sharing food, eating utensils, or cups with anyone.
• Avoiding crowded places where cold germs can spread.
• Eating a healthy diet and getting adequate sleep.
(Author is a Medical Practitioner)