MARCH 25, 2001

The Straits Times, Singapore
Blame it on the sun

A team of Canadian scientists who went through historical records says there is a link between heightened solar activity and flu outbreaks

By R. Senthilnathan

THERE may be a link between flu epidemics around the world and sun spots.

So say three scientists in an essay in the Canadian Journal of Infectious Diseases.

The team said it came to the conclusion after going through historical records of heightened solar activity, called solar maximum, and flu epidemics.

'When going through past records, one gets a four times increase in the likelihood of a flu pandemic around solar maximum,' said team member Ken Tapping.

A sign of heightened solar activity is the emergence of sunspots, dark patches appearing on the surface of the sun.

They occur when the strong magnetic field around the sun gets twisted and pokes up through its surface, reducing the temperatures in those spots.

Enormous amounts of energy can also be released during these activities.

Such solar activity goes through an 11-year cycle.

The number of sunspots and related solar activities reaches a peak during the 11th year, which is called the solar maximum.

The cycle then moves towards solar minimum, at which point the least number of sunspots occur.

The sun is at its brightest during the peak of the cycle, and its impact on earth is felt by trees and plankton, for example, which show growth increases during this time.

Scientists have noticed that flu epidemics also appear at intervals of between 11 and 42 years.

They usually begin in Asia where people and domestic animals live in close proximity.

The authors of the essay in the Canadian Journal of Infectious Diseases used records of solar activity that were available from 1700 as the starting point for their study.

'We concluded - by studying the solar activity and influenza records - that there is a significant probability that influenza epidemics are most likely during solar magnetic activity maximum,' they wrote.

The worst known epidemic was the so-called Spanish flu in 1918 - a sunspot year - when an estimated 40 million people died.

Initially, it was believed that only 20 million died, but the death toll keeps increasing as scientists come up with new evidence.

The last major flu outbreak occurred in 1968, another solar maximum year.

Health officials fear the next flu outbreak is due soon.

Their fear has been reinforced by minor flu outbreaks, such as the so-called bird flu in Hongkong in 1997-98.

Solar activity is at its peak currently.

Although the essay authors believe there is a link between solar activity and these epidemics, they say they do not know just what in the sun, or in its sunspots, causes the various flu viruses to be affected, or to mutate and spread the epidemic.

'We are unable to conclude what might be the reason for the epidemics during the solar maximum,' said Mr Tapping.

'We have some ideas we are discussing privately, but are at this point trying to think of suitable tests.'

They hope their colleagues in the scientific community would also begin studying the link.

If further research bears out their theory, the next time you have the flu, you can blame it on the sun.

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