Common Cold

Common cold

PKGhatak, MD

The common cold is really very common. It is said that every adult gets 2 attacks and every child 6 attacks of the common cold every year. The common cold is the number one viral disease of humans.

There are about 200 different viruses responsible for the common cold including three groups of coronaviruses, however, Rhinovirus is responsible for 50 % of the common cold. The common cold is also called Head Cold and Viral URI (viral upper respiratory infection)

Rhinovirus is an RNA virus. It thrives in the nose because the virus prefers 89 degrees F and the nose temperature is very close to it, as opposed to the core body temperature of 98.6 degrees F. It is also true that exposure to cold makes a person susceptible to rhinovirus infection.

Covid-19 pandemic made people aware of viral infections. The mode of the viral spread and symptoms of illness are understood by most people. Public health officials repeatedly advised people how to protect themselves from this respiratory viral infection and to minimize the spread of the virus to others.

People have learned that viruses are inert particles, like darts until the virus gets a foothold in a living individual. The virus then enters inside the cell and directs the cell DNA /RNA to copy virus particles. In the end, the cell walls are broken open and viruses are released, newly released viruses infect more healthy cells. The rhinovirus uses ICAM receptors to attach to the nasal epithelium and then enter inside the cell.

Covid pandemic has produced havoc in the way we live, work, socialize, and carry out other activities. Most of these are detrimental to human society except for one benefit - during the period of social distancing and hand washing the common cold has almost disappeared.

In early human history, the common cold viruses found humans an easy target to attack, infect, multiply and live in perpetuity. The human immune system is unable to maintain a good defense against the common cold viruses. A vaccine, for the same reason, has not been effective. Recently, MedUnite of Vienna found that the human immune system produces antibodies against the RNA genome of rhinovirus but not against the capsid protein which is necessary to kill the rhinovirus. That is responsible for repeated rhinovirus infections.

Children are nursery going age, young adults on college campuses, military recruits, people in cruise ships, sailors in submarines and other ocean-going vessels and institutional residents are prone to repeated common colds.

Infants and young children suffer the most because their airways are narrow and they are not able to cough sputum up. Elderly and disabled nursing home patients develop complications more often than any other group and also die in a higher proportion.

The diagnosis.

Viral URI is diagnosed by eliminating bacterial URI.  The most common bacteria causing URI is GAS (group A streptococcus). The textbook lists certain signs like - a temperature of 104 degrees F or higher, swollen red tonsils, strawberry tongue, petechiae on the hard palate and cervical lymph node enlargement are usually findings in bacterial URI; but physicians depend on the Rapid Strep Test (RST). The RST detects a GAS antigen, taken from the throat by a swab and mixing it with known GAS antibodies; and at times blood WBC count is necessary.

Complications.

A middle ear infection is common in children, and difficulty in breathing may require hospitalization. Elderly people may develop viral pneumonia, and at times viral URI makes them susceptible to bacterial pneumonia.

Prevention.

A molecule, SETD3 (set domain protein 3) has shown promise in blocking rhinovirus replication by interfering with the methyltransferase of rhinovirus.

If you read this article hoping to get answers to one or two questions you wanted to know about the common cold; I hope you got them here.

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