Common cold
The common cold is a common viral infectious disease of the nose and throat, the upper respiratory system. Its symptoms are sneezing, sniffing, scratchy throat, coughing and headache; they typically last for 4 to 11 days.
The common cold is the most common of several upper respiratory tract infections; it is different from influenza, which is a more severe viral infectious disease that shows the additional symptoms of rapidly rising fever, chills, and body and muscle aches.
Pathology
The common cold is caused by several viruses (mainly rhinoviruses, coronaviruses and also certain echoviruses and coxsackieviruses). These are transmitted from person to person by droplets resulting from coughs or sneezes. The droplets are either inhaled directly, or, more commonly, transmitted from hand to hand via handshakes or door knobs, and then ingested when the hand touches the face.
The term "cold" is misleading, as the temperature does not appear to play a role, nor are any other factors known which affect the probability of infection. Colds are somewhat more common in winter since during that time of the year people spend more time indoors in close proximity of others, increasing the infection risk. Furthermore, the drier air in winter causes the mucus of the nose to dry out, which may allow for easier entry of the virus. Some factors influence the severity of symptoms, for instance psychological stress and position in the menstrual cycle. Also, weak health in general, or other pre-existing conditions such as allergies can be aggravated due to infection.
The virus enters the cells of the lining of the nose and throat, and multiplies inside them. The symptoms are a result of the body's defense mechanisms: sneezes, runny nose and coughs to expel the invader, and inflammation to attract and activate immune cells. The virus takes advantage of sneezes and coughs to infect the next person just in time before it is killed by the immune system.
Prevention and treatment
Treatment for the common cold is designed to relieve the symptoms rather than attack the cause. Common treatments include analgesics such as paracetamol (acetaminophen) as well as localised versions targeting the throat (often delivered in lozenge form), nasal decongestants (which work to reduce the inflammation in the nasal passages) and cough suppressants (which work like a narcotic to suppress the cough reflex of the brain).
A warm and humid environment and drinking lots of fluids, especially hot liquids, alleviate symptoms somewhat. Common home remedies include camomile tea, chicken soup, nebulized medicinal mixtures, hot compresses, mustard plasters, hot toddies, vitamin C, and Echinacea.
For most people, even without these remedies, colds are relatively minor inconveniences and they can go on with their daily activities with a little discomfort.
Antibiotics are ineffective against the common cold and all other viral infections.
To prevent infection, frequent hand washing is helpful, especially if infected people are around. In some countries, people with the common cold wear surgical masks out of courtesy. Because of the large variety of viruses causing the common cold, vaccination is impractical.
Societal Impact
Common colds interfere with school attendence and can cause lost days on the job, resulting in considerable costs to the economy. In addition, much money is spent on over-the-counter and home remedies.
Research
In Britain, the Common Cold Unit (CCU) was set up by the civilian Medical Research Council in 1946. It continually recruited volunteers for research into the common cold until its closure in 1989.
See also
