By Tuesday morning the World Health Organisation had raised its pandemic alert level up to four out of a possible six as new cases emerged in Europe, America and Australia.
We need to be careful not to panic.
So far, this outbreak of swine flu has crossed the species barrier and it has spread quickly from human to human. It appears to have mixtures of human, bird and various swine subsets in its make-up. Most people who have caught it have only had mild cases of flu.
However, of the more than 1600 Mexicans who have caught it, more than 150 have died. What is alarming public health experts is that among those who have died are apparently healthy adults.
The difference between the Mexican and all other cases is a variable that has not yet been properly explained.
But it may be that the Mexicans were not as fit as others confirmed with the disease. It's a common pattern during a disease crisis; people in the majority world tend to be more vulnerable to more serious levels of illness and so die in higher numbers.
We fear the pandemic because of the Spanish flu of 1919. In that pandemic between 20 to 40 million people died worldwide, more than the number killed in the First World War. It was one of several times last century when swine flu crossed the species barrier, but it was the most serious.
Since then public health officials have been expecting another outbreak on the same scale. The more time passes without one, the more they worry that it is getting closer. Every time swine flu crosses the species barrier and turns up in humans, they become extremely nervous.
The consequences of an outbreak of swine flu in America, at Fort Dix, New Jersey, in 1976, are still discussed in medical journals. Out of fear of another horrendous pandemic, American health officials reacted quickly. Before long, a massive flu vaccine program was begun, with the goal of avoiding the scale of the 1919 losses.
The program was not abandoned until 25 per cent of the population had been vaccinated. Epidemiologists and others still discuss the futility of the exercise, observing that a pandemic was never likely. Instead, 500 people developed Gillian Barre syndrome, a nasty neurological disorder as a side effect, and 25 of these died.
There have been other outbreaks of swine flu and scientists have noticed that the pace of outbreaks is increasing, while more sub-types are emerging.
Swine flu is not the only disease to cause such anxiety. In 1997 in Hong Kong there was a serious outbreak of avian (bird) flu among humans. Even though only 18 people became ill, six died, suggesting this strain was particularly deadly. In response, all Hong Kong's poultry, about 1.5 million birds, were killed.
In 2003, the world braced itself for an avian flu pandemic, as reports of human deaths emerged from Europe and several South East Asian countries. This came hot on the heels of the severe acute respiratory syndrome (SARS) outbreak, which damaged many South East Asian economies as tourism and commercial travel dwindled.
According to an Asian Development Bank report prepared by Jean Pierre Verbiest and Charissa Castillo, three aggressive steps were put in place to suppress the outbreak of avian flu in Asia: massive culling of chickens on a widespread scale, monitoring of humans, and the introduction of disease prevention measures at airports.
The impact on South East Asian economies was immediate and devastating.
Of course not to do anything would have been unacceptable. But it was the poorer farmers of the South East Asian countries who were affected most dramatically. They had fewer financial reserves and fewer government subsidies to cushion the blow, as all their livestock and therefore their source of income was destroyed.
A paper by the South Asian Regional Centre for Graduate study and Research in Agriculture noted that, typically:
'In Vietnam, they experienced a 17.5 per cent loss in their total poultry production, equivalent to over 44 million birds. Citing the World Bank study, losses range from 0.3 to 1.8 per cent of Vietnam's Gross Domestic Product (GDP). Moreover, 29 million birds or 14.5 per cent of the country's poultry population died, resulting in a radical 1.5 per cent loss in their GDP.'
As it turned out, the consequences of the threat of avian flu turned out to be far greater than the disease itself. In the end, the pandemic did not eventuate. This was because of a combination of the dramatic bird cullings and an element of good luck. While avian flu crossed the species barrier from animals to humans, it moved from human to human only very slowly.
Rich countries stockpiled enough anti-virals during the avian flu scare to minimise the effect on their citizens if the swine flu hits. Poor countries have no such luxury. Rich countries are working on vaccines, which could be available in six months time. Once again, rich countries will be at a distinct advantage over poor countries.
Those countries which produce flu vaccines and anti-virals have had a little shot in the arm this week. Amid the general gloom of stock markets flattened by the global financial crisis, medical companies' stocks have risen since Monday, particularly those which produce ant-virals.
ABC TV's commentator Alan Kohler sagely noted on Monday night that an Australian company's share price had risen by 82 per cent because it produces one of the most promising modern anti-virals. Again, there are winners, but only in rich countries.
As the world holds our collective breath, hoping that this flu will peter out quickly, let's spare a thought for those poorest countries, which will take the losses the hardest.
Margaret Rice is a Sydney-based freelance journalist
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