Demystifying the Common Cold

Tahsin Tabassum

Sophomore

School of Life Sciences

Independent University, Bangladesh

June 1st, 2017

The common cold needs no introduction. We are all intimately acquainted with its symptoms and spread. But for a disease that occurs at an average of two to three times in adults and six times in children every year, its exact causes are not particularly well understood by the general population, and to a lesser extent, even by scientists. Broadly speaking, it is a viral infection that can be caused by more than 200 different types of viruses. The viruses mostly infect the upper respiratory tract including the throat and nose. The most common types of cold viruses that infect the body are rhinoviruses, corona viruses, respiratory syncytial virus (RSV) and parainfluenza virus. Rhinoviruses, the most common causative agents, cause up to 40% of all cases, and tend to be active during early autumn, spring and summer. Unknown viruses cause 20-30% of the infections, which is an endless source of consternation for scientists trying to develop vaccines against the disease.

A cold begins when viruses attach to cells in the lining of the nose and upper respiratory tract. Upon infection, the immune system (the body’s defense mechanism against germs) sends immune cells to attack these foreign cells. The immune cells release chemicals called cytokines in response to the infection. One of these cytokines, IL-6, is responsible for raising the body temperature, alongside causing inflammation. A raised temperature reduces the ability of the pathogens to reproduce effectively and cause damage. Meanwhile, the body overproduces mucus in the airways. Mucus is a sticky substance that lines the respiratory tract in order to trap dust and microbes that we breathe in with air. Beating cells called cilia constantly move mucus that has trapped particles up the respiratory tract; we subsequently swallow the mucus, and the viruses are destroyed by the acid present in our stomachs. Overproduction of mucus occurs as a result of the body trying to clear the virus. Symptoms of the disease are thus often caused by the body’s response against the cold virus. The virus takes advantage of many such symptoms, such as sneezing and cough, to spread to other individuals.

A poster from Great Britain during the Second World War. © IWM (Art.IWM PST 14140)

Symptoms vary in range and severity among individuals, but generally begin to disappear around a week after infection. The frequency of the disease decreases with age as children build up immunity or protection against many of the viruses they have already been infected by. It is easy to be dismissive of this relatively mild disease, but the common cold has significant economic costs through its effects on productivity in the workforce. How many sick days have you taken after you have come down with a bad cold?

Despite being such a commonly experienced ailment, various myths and misunderstandings persist about the common cold. Contrary to popular belief, being wet for too long or consuming cold things such as ice-cream in cold climates do not cause infection on their own. People also tend to often avoid dairy products when they have a cold because of the prevalent myth that these products increase mucus production. This is not true, and dairy products are actually recommended to help soothe sore throat. Symptoms of the common cold are also often confused with other conditions such as the flu as well as certain allergies as they have some similar symptoms such as runny nose and sore throat. However, it is important to distinguish between them in order to be able to decide on the course of treatment. The flu is caused by the influenza virus, for which specific drugs exist, while allergies occur as a result of an unregulated immune response to otherwise harmless substances found in our food and the environment, and are treated very differently from viral infections.

As for the common cold, there are no specific prevention or cure strategies. As a large number of different viruses are responsible for the common cold, it has not been possible so far to create a vaccine to protect against it, although a few are in the process of being developed. When infected, alongside the commonly observed strategies of rest, regular fluid intake to thin out the mucus, and taking decongestants to relieve nasal congestion and other symptomatic treatments, one should also take care to minimize contact with other individuals in order to limit spread.  If around infected individuals, maintaining good personal hygiene and wearing a face mask can go a long way to reduce risk of infection. 

Tahsin is a scientist-to-be with incredibly insane ideas and a soul full of ambitious dreams.