You don't have to look at a calendar to know that it is cold season. Just listen to the hacking coughs, sneezes and the hoarse, husky voices that have dropped an octave as upper-respiratory tract infections take a toll in offices, schools and homes.

The common cold is the most frequent illness known to man. But sufferers can feel uncommonly bad to have blocked nasal passages, watery eyes and head-snapping sneezes.

And, in an era of heart transplants, in vitro fertilisation and human genome mapping, there is still no treatment for this malady that accounts for around mately 500 million infections annually in the US alone.

And the costs? An estimated $40 billion (Dh146 billion) each year, according to a 2003 economic analysis by the University of Michigan, for both direct and indirect costs for medical treatment and lost work time. As the researchers noted, that is a higher economic burden than what some morellserious conditions impose.

This eagerness to be rid of cold symptoms can sometimes exact a human toll. In January, the federal Centres for Disease Control and Prevention in the US linked infant deaths to overuse of cold remedies and advised parents and caregivers not to give children who are two or younger cold medicines without a doctor's approval.

Flu or cold?

Cold sufferers complain that their flu shots did not protect them against the common cold. (The shots are not for that purpose. Influenza is caused by different viruses.)

Nor can most people tell the difference between the flu and a cold. Both cause respiratory symptoms, but influenza is a far more severe infection that comes with a fever, headache and muscle aches as well as a gut-wrenching cough. And, unlike the common cold, influenza can be treated with antiviral medicines, provided they are started immediately after the symptoms appear.

Scientists have not yet been able to get their heads around this infection and its many symptoms. But a Spanish fisherman recently helped researchers identify what they believe is the sneeze control region of the brain. While fishing, the man suddenly sneezed violently about 20 times, then became dizzy, disoriented, and could not walk.

Medula clue

At the hospital in Villagarcia de Arosa, neurologist Manuel Seijo-Martinez diagnosed a stroke. Tests showed that it had affected a region close to where the spinal cord meets the brain.

Seijo-Martinez tested the man's sneezing reflexes by touching the inside of each nostril with a cotton-tipped stick.

"What really shocked me,'' says SeijollMartinez, "is that if you touched the right nostril, he would not sneeze.'' But tickling his left nostril produced a sneeze. (And the man recovered otherwise.)

From that information, Seijo-Martinez concluded in a paper published last year in the Journal of Neurology, Neurosurgery and Psychiatry that the sneeze control in the brain appears to be in the medulla.

That is one step towards understanding the mysteries of colds and their many symptoms ll and, perhaps, controlling them better.

By Sally Squires, Los Angeles Times-Washington Post News Service

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