Flu a bigger threat than Aids?
2004-01-27 19:22
Paris - World health officials have a store of evidence to back their warning on Tuesday that if bird flu mutated into a more contagious form it could kill millions of people.
That assertion may seem overblown to those for whom influenza is just a cold with attitude - a bad case of the snuffles with fever, headache, coughing and muscular aches thrown in for good measure.
But the truth, say researchers, is quite darker.
Flu is a changeling, a survivor, a stealthy assailant which, in its most pathogenic strain, could rip around the world.
Indeed, the 1918-19 strain of so-called Spanish flu killed an estimated 40-50 million people: around twice the number of people who have died from Aids, a disease that is now in its 23rd year.
Invariably, of course, flu circulates in a far milder form.
Even so, it can still endanger the young and elderly and people with chronic heart or lung problems or a pre-existing condition such as diabetes or kidney disease. The biggest risk is pneumonia, a common effect of flu infection.
Each year, "several hundred thousand people" die from flu, says World Health Organisation (WHO) spokesperson Iain Simpson, the agency which sounded the alarm on Tuesday about the killer potential if Asia's bird flu merged with human influenza.
Indeed, flu is such a problem that the WHO classifies it as a pandemic. It is a permanent health hazard that shifts from the northern hemisphere to the south and back again, in line with the respective winter there.
Rivals in the league of nasty diseases may grab the headlines for the lurid way they kill, but the real champion could be flu.
Unlike plague, cholera and malaria, this disease does not need poor hygiene or a tropic insect host to spread.
Unlike the Aids virus, it does not need sexual intercourse, blood transfusion or shared use of drug syringes to be transmitted. Breathing in airborne, virus-laden droplets, coughed or sneezed by someone in proximity, is enough.
That means it can spread swiftly around the world, because air travellers can take the disease to another country without even knowing they have it.
But flu's most feared characteristic is its ability to change.
Small shifts in its DNA code, called mutations, occur frequently in a viral strain. Usually, though, the change is so small that the new strain is not much different from the strain that circulated the previous year.
More troubling is a bigger change, involving a swapping of genes with other viruses.
This is why a mixture of bird flu and a common human influenza virus is so feared.
Bird flu (strain H5N1) is only transmitted from poultry to humans, but not from humans to humans.