- diseases - health - INFLUENZA A (H1N1) - Mexico - USA
AFP - The World Health Organisation on Thursday said that in a pandemic situation it was "reasonable" to estimate that a third of the world's population would catch the swine flu virus.
"If you look at past pandemics, it would be a reasonable estimate that a third of the population would be infected" if the current swine flu outbreak became a pandemic, said Keiji Fukuda, acting assistant director general of the UN health agency.
Fukuda had made the point in response to mounting concerns that the WHO may have over reacted given that most swine flu cases have turned out to be mild.
The WHO had raised its pandemic alert level to five out of six last week, signaling that a pandemic was "imminent" after the flu appeared to be spreading locally not just in Mexico but also in the United States.
The move prompted countries to activate their pandemic alertness plans.
Fukuda said when considering how to deal with such outbreaks, the WHO has to take into account the fact that in a full-blown pandemic, even if only a small percentage of people were to develop serious illness or die from the disease, it would translate into a large absolute number of people.
Fukuda stressed however that his estimate was based on past pandemics and that "we live in a different world."
He added that "very premature" to forecast how many could die from a pandemic as it remained unclear what proportion of infected people were getting seriously ill or dying from the influenza A(H1N1) virus.
The UN health agency had estimated in a background document before this outbreak was known that a pandemic could lead to the deaths of between two to 7.4 million people around the world.
Fukuda said the situation surrounding the disease was still "evolving."
The virus could yet mutate into more dangerous forms.
"One of the absolute statements that you can make about influenza viruses is that they change," he said.
With the southern hemisphere heading into winter, it was also uncertain if the virus would take hold in that region where there were more developing countries than richer countries as in the northern hemisphere, he added.
"We also have a population which are more vulnerable... this may be because of malnourishment, this may be because of war, this may be because of conditions like HIV infections," he said.
He noted that in past instances, such flu outbreaks may turn out to have a "relatively mild" impact on the developed world, but turn out to have a "quite severe" impact on the developing world.
Earlier Thursday, Fukuda told 13 Asian nations meeting in Bangkok to remain vigilant against the disease even if it now appears to be milder than what caused earlier pandemics such as the 1918 Spanish flu which killed at least 40 million people.
The WHO said 2,099 people have been confirmed to have contracted influenza A(H1N1), with 44 having died from the disease.