Causes for the Common Cold

There are many different types of viruses that can cause cold symptoms; and among these viruses, there are approximately 200 different variations (serotypes). Viruses that can cause cold symptoms include:

• Rhinoviruses (account for 30%-50% of colds)
• Coronaviruses (account for 10-20% of colds)
• Respiratory Syncytial Virus (RSV)
• Adenoviruses
• Parainfluenza viruses
• Enteroviruses

Some viruses that cause the common cold can also cause other illnesses. For instance the respiratory syncytial virus (RSV) and parainfluenza virus are also leading causes of lower respiratory tract infections (pneumonia, bronchitis, and bronchiolitis).

Colds are spread when people come into direct contact with the virus, which can be found in nasal secretions and saliva. It is believed that the virus most often enters the body through touching the eyes, nose or mouth with unwashed hands that have come in contact with secretions. Viral contact may come through:

• Direct contact with the person (i.e. cuddling a sick infant or child, kissing)
• Contact with secretions on environmental surfaces (i.e. countertops, shared drinking cups or utensils, door knobs, shopping cart handles, crib rails etc)
• Contact with mucous particles in the air (sneezing and coughing)

Colds can be experienced at any time during the year but are more frequent when the climate is cooler. Possible reasons for an increase in colds during the cold season include:

• Some cold viruses may survive best in cooler temperatures and low humidity.
• Large numbers of students attend schools during the cold season and the close contact makes it easier for viruses to spread.
• More people frequent indoor places during cooler temperatures, (i.e. homes, malls, movie theatres, classrooms et.) making it easier for colds to be passed from person to person.