Claire Fraser, of Ilam School, asks :-

How do people get colds?

Mel Brieseman, the Medical Officer of Health for Canterbury, responded.

From someone else who has a cold. A 'cold' is the name we use to describe symptoms of an infection of smallgerms (virus) inside the nose. While lots of different viruses can cause these symptoms the main viruses are a type called rhinovirus. These viruses enter the nose and cause irritation which produces a runny nose, sneezing and a sore throat, etc. The viruses are spread either through the air by tiny drops or by contact with items which have on them the discharges from the nose, including the hands.

Following the virus infection, larger germs called bacteria may invade the lining of the nose. This causes the change from the initial clear runny discharge to a thick yellow discharge a few days later. Bacterial infection may spread to other parts of the respiratory (breathing) system, such as the sinuses or lungs and bronchi (breathing tubes) as complications of the original cold.

Colds are more common in winter because in winter people spend more time indoors to avoid the cold weather. This results in more contact and makes passing the virus on easier. Also in cold weather the nose is moister which provides a better breeding ground for any viruses which may gain entrance.

There are lots of other causes of runny noses, such as an allergy (like hayfever), which may get called a 'cold', but which are not in fact virus infections and are not caught from another person.