Common Cold

I

Introduction

Common Cold, acute infectious disease of the upper respiratory tract, caused by more than a hundred kinds of virus. The infection affects the mucous membranes of the nose and throat, causing such symptoms as nasal congestion and discharge, sore throat, and coughing. These symptoms are also typical of respiratory infections caused by bacteria, and of allergic conditions such as hay fever and asthma. Influenza may also produce the same symptoms as a cold but with a higher fever and more pronounced malaise, headaches, and aches in the joints. Nasal congestion and headaches may indicate rhinitis or sinusitis.

II

Symptoms

Normally, a cold runs a mild course, without fever, and subsides spontaneously in about seven days. Its medical significance lies in the possible complications that may ensue. Various diseases, such as bronchitis, pneumonia, and sinus or middle-ear infections, may arise from a cold. Research indicates that there are several strains of each type of virus with varying degrees of virulence. Infection with one strain confers only a brief immunity to reinfection by the same strain, and gives no immunity against the other strains.

Study of the antibody binding sites on the viral coat reveals a very high degree of antigenic variability, suggesting that production of a vaccine to protect people from the common cold may never be practical.

III

Causes

The common cold was formerly thought to result from exposure to cold weather, a belief probably traceable to the fact that people tend to crowd together indoors at this time, causing a more efficient transmission of virus from person to person. Cold viruses are spread via the nose, not the mouth, in droplets produced by sneezing; but almost three quarters are from hand-to-hand contact, followed by touching the nose or eyes, or touching a telephone or other objects already handled by a sufferer. Chilling, also believed to cause a cold, may contribute to infection, but some studies suggest that it is not of major importance. Some 40 per cent of colds are caught in the summer. Some studies have been conducted into the influence of stress on the immune system and on a person's susceptibility to colds and their severity. In Britain the Common Cold Research Centre used to carry out such studies.

IV

Treatment

No cure is known for the common cold and no preventive drug has yet been found. Various antihistamine drugs were formerly claimed to be effective in the prevention of colds if taken at the onset, but are now discredited; most doctors believe that such drugs cannot affect the progress of the true, virus-caused cold. The American chemist and Nobel laureate Linus Pauling proposed that large doses of vitamin C can shorten the duration of a cold and alleviate its symptoms, but several studies have failed to substantiate his claim. However, vitamin C is thought to boost the immune system and to reduce inflammation.

Present-day methods of treating a cold are directed towards the relief of symptoms through over-the-counter preparations, particularly those containing aspirin. An assortment of remedies exists which may soothe cold symptoms but do not shorten its duration. Bed rest is commonly recommended to avoid complications, even when the cold itself is not incapacitating and it is important to drink plenty of fluids. Antibiotics should not be administered as a preventive measure, as colds are caused by viruses, not bacteria. Such overuse of antibiotics only serves to enhance resistance to these drugs. They are only advisable when the person has developed a secondary bacterial infection, or has a primary throat infection caused by streptococci bacteria, such as tonsillitis. Research is being conducted into the role of prostaglandins released by the body during a cold and thought to be the cause of pain in chest congestion and sore throats.