Race to research: To study the virus, scientist Isabell Wendel infects chicken embryos in their eggs with it at the Virology Institute of the Marburg University, in Germany.
Credit: AFP
"There's no good explanation [for why people are dying in Mexico and not anywhere else] although there are very few confirmed cases outside of Mexico yet so we need to be cautious about extrapolating that," says Read.
It could be that there simply aren't enough cases outside Mexico for the virus' ability to kill people to have been manifested.
Another possibility put forward by scientists is that, in Mexico, victims are dying of secondary infections because the healthcare system is not reaching them in time and there is widespread antibiotic resistance.
Genetic similarity
It is even possible that the virus is gradually adapting to its human hosts and becoming less dangerous as it passes from person to person. Fukuda, however, has rejected this theory on the basis that all samples of the virus examined so far have been very similar.
"What we need to know is why we're seeing a different disease spectrum in Mexico than we're seeing [in the United States]. As we continue to look I expect that we will see additional cases and I expect that the spectrum of disease will expand," Richard Besser, the acting head of the U.S. Centres for Disease Control and Prevention (CDC), told a press briefing..
There are also reports that most of the deaths in Mexico have been in young to middle-aged adults – all of those who have died were aged between 20 and 50, Health Minister Jose Angel Cordova told the BBC.
Immune overdrive
This is a hallmark of the 1918 flu pandemic, says Read. "The thinking is that if you've got a fit, active immune system it goes over the top in trying to fight the disease and that's what causes most of the disease symptoms and causes a build-up of too much fluid in the lungs."
Even the genetic makeup of the virus is under debate. Scientists agree that it is a H1N1 virus – named because of the types of haemagglutinin and neuraminidase proteins that it possesses. According to some analyses it is made up of an assortment of human, swine and avian influenza genetic material, while the WHO is saying it is made up of largely swine influenza genes.
"By and large when you analyse this virus it is a swine influenza virus," said Fukuda. "I appreciate the difficulty of keeping all of this straight but these are new viruses — they're new for pigs and they're new for people."
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mutated swine virus
One theorie as to why there is more deaths in mexico is that there is two different strains of this virus out there.The strain in mexico may have mutated again and current vaccines and medications are useless.The virus may mutate to create a virus that is either fully airbourne or it could change the incubation period for the virus.If the incubation period changed from 5 days to two weeks that would be a total disaster.People may contract the disease and may not show the first signs for 10 days to two weeks.Again how many times have this virus mutated and if it will mutate in the furture.Some medications that don't kill ther virus may in fact help the virus to mutate to another strain.