How We Actually Catch Cold and Flu Viruses

When someone has a cold, the nasal secretions are teeming with cold viruses. Coughing, drooling, and talking are all unlikely ways to pass a cold. But sneezing, nose-blowing, and nose-wiping are the means by which the virus spreads. You can catch a cold by inhaling the virus if you are sitting close to a sneeze, or by touching your nose, eyes, or mouth after you have touched something contaminated by infected nasal secretions.

Once you have "caught" a cold, the symptoms begin in 1 to 5 days. Usually irritation in the nose or a scratchy feeling in the throat is the first sign, followed within hours by sneezing and a watery nasal discharge.

Inhaling droplets from coughs or sneezes is the most common way to catch the flu. Symptoms appear 1 to 7 days later (usually 2-3 days). The flu is airborne and quite contagious, and with its short incubation period it often slams into a community all at once, creating a noticeable cluster of school and work absences. The flu usually arrives in the winter months. Within 2 or 3 weeks of its arrival, most of the classroom has had it.

Looks Like Mom Might Have Right All Along

Mothers and grandmothers have long warned that chilling the surface of the body, through wet clothes, feet and hair, causes common cold symptoms to develop.

But much previous research has dismissed any link between chilling and viral infection as having no scientific basis.

Now researchers in Cardiff, Wales, say they can prove drops in temperature to the body really can cause a cold to develop. (Watch what they did to 'chill' people in the study -- 3:24)

Claire Johnson and Professor Ron Eccles, from Cardiff University's Common Cold Center, recruited 180 volunteers, half of whom they got to immerse their feet in ice and cold water for 20 minutes.

The other 90 in tests during the common cold "season" sat with their feet in an empty bowl.

During the next four or five days, almost a third (29 percent) of the chilled volunteers developed cold symptoms -- compared to just 9 percent in the control group, the scientists said.

Professor Eccles said there was a simple explanation as to why chilly feet could lead to the development of cold virus symptoms.

"When colds are circulating in the community many people are mildly infected but show no symptoms," he said, according to the UK's Press Association.

"If they become chilled this causes a pronounced constriction of the blood vessels in the nose and shuts off the warm blood that supplies the white cells that fight infection.

"The reduced defences in the nose allow the virus to get stronger and common cold symptoms develop.

"Although the chilled subject believes they have `caught a cold' what has in fact happened is that the dormant infection has taken hold."

The researchers, writing in the UK medical journal Family Practice, said that common colds were more prevalent in the winter than the summer, and this could be related to an increased incidence of chilling causing more clinical colds.

But they also suggested that another explanation could be that our noses are colder in the winter.

Professor Eccles added: "A cold nose may be one of the major factors that causes common colds to be seasonal.

"When the cold weather comes we wrap ourselves up in winter coats to keep warm but our nose is directly exposed to the cold air.

"Cooling of the nose slows down clearance of viruses from the nose and slows down the white cells that fight infection.

"Mothers can now be confident in their advice to children to wrap up well in winter."

Cardiff's Common Cold Center says it is the world's only center dedicated to researching and testing new medicines for the treatment of flu and the common cold.

Source: CNN