As countries around the world ready themselves for the possibility of a global pandemic in the wake of increasing numbers of confirmed cases of people infected with a new strain of A/H1N1 influenza virus that is being described as swine flu, investigations digging deeper into the history and evidence surrounding the outbreak are coming up with more questions than answers. Is it swine flu? How did it start? How deadly is it?

The Food and Agriculture Organization of the United Nations is sending a team to Mexico to investigate the link between this virus and pigs. Until they report their findings, there is no evidence that this latest new strain is actually swine flu, and that it started in pigs. All we know is that it is the same type as that which normally occurs in pigs, A/H1N1.

Joseph Domenech, chief veterinarian of the Food and Agriculture Organization of the United Nations, said in an interview on BBC’s Radio 4’s The World Tonight yesterday that one of the goals the investigators will be pursuing will be to rule out the possibility that pigs were involved in the genesis of the new virus, and also to establish an appropriate response to the possibility that pigs may catch the virus from humans.

Domenech said that all we know is that the virus contains pieces of genes from “human, avian and pig origin”, and “this crisis should not have been named swine influenza”.

He explained there was no evidence so far (which is why they need to investigate further) that the virus started in pigs, because when H1N1 starts in pigs the virus is so virulent that it spreads fast in pigs and you soon get to know about it. But there have been no reports of large numbers of pigs getting swine flu, all we have is evidence of human to human infections.

None of the confirmed human cases has a history of being in recent contact with pigs, so the most likely explanation at the moment is that this is a new strain of H1N1. The reason it was called swine flu at the start of this crisis, he suggested, was because H1N1 is more commonly found in pigs, but to date there is no evidence that it did so in this case.

However, because the strain does have some element of pig flu genes in it, other experts are suggesting it might be too early to be sure it is not swine flu: for pig genes to get into the virus it must have circulated in pigs at some point in its genetic past.

Officially we don’t know the answer, because UN experts have only just started to investigate the origins of this particular new strain of influenza virus, however, news sources are reporting the curious case of 5-year-old Edgar Hernandez, a Mexican boy who is thought to be the first confirmed victim.

Edgar lives in La Gloria, a town of some 3,000 residents that lies 200 km to the east of Mexico City high in the mountains of the state of Veracruz, and which is now being reported as “ground zero” of the new strain of flu that is making its way around the world.

According to an Associated Press report yesterday, samples taken from 35 La Gloria residents who had flu recently were sent away for testing and only Edgar’s came back positive for the new A/H1N1 strain at the centre of the global controversy. Edgar, who has never travelled outside of the Perote valley, and whose family has no contact with Mexico City, and don’t keep or go near pigs in their everyday lives, was confirmed last week to be the first known case of the virus in Mexico. Edgar was sick over a month ago and is now fully recovered.

Local and federal health officials are downplaying suggestions that the epidemic started in La Gloria however, and insist that the other 34 cases came back positive for a completely different and common strain of flu, H2N3. Governor of Veracruz, Fidel Herrera, told the press there was not a single indicator that the epidemic started in La Gloria.

However, the townspeople are not convinced, especially since they suspect their water and air is contaminated by a pig farm that lies upwind in the Perote Valley less than 10 km away and is home to some 1 million intensively farmed pigs.

According to a report in the Los Angeles Times earlier today, Devlin Kuyek of GRAIN, an environmental organization, said there have reports over the last few months of the appalling conditions in the region surrounding the farm. Local people have been infested with flies, they complain of a fearful stench, and since last December, 60 per cent of the community has been ill with respiratory problems.

According to Kuyek most people were never tested and some samples have disappeared.

Another mystery about this new strain is that in Mexico it appears to be killing people, and yet outside Mexico it is not.

Experts have suggested a number of reasons: perhaps the deaths in Mexico were complicated by other medical problems and diseases, perhaps the number of cases outside Mexico are not yet high enough for the true statistical nature of the fatality rate to reveal itself (over 1,600 cases reported in Mexico, fewer than 100 elsewhere).

But, there is another possibility that is only just emerging, and that is that the deaths perhaps were not due to this virus after all. Speculation that this may be the case is gaining ground as Mexico’s health minister has now also announced that the previous number of confirmed deaths has gone down from 20 to 7.

So it is very difficult to say how deadly this new virus is. It depends on how good the surveillance is, because in order to say how deadly it is you have to count all the cases and all the deaths and divide one by the other. But how are the cases being counted? If the only way cases are counted are when people go to hospital, then if the virus is not highly virulent but more likely to be experienced by most people as a mild dose of flu, then who is going to report or count the mild cases to make sure they enter the equation?

Another problem is that countries differ in the way they conduct surveillance, so it will be some time yet before the story is “joined up” enough for us to be able to say how deadly this new strain is.

What we do know is that there is no vaccine against this virus, and it may take months to develop one. But it responds well to early treatment with conventional flu drugs, based on the cases reported so far.

Although they are not saying it out loud, one suspects that what many experts are thinking, is that we can be grateful that it is this strain, and not the highly fatal H5N1 bird flu strain that we are finding ourselves responding to around the planet. Hopefully this experience will help us rehearse and improve our responses to such a worst case scenario and not make us complacent about whether it will ever happen.

Sources: BBC, Los Angeles Times, Associated Press.