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
LONDON: Scientists trying to gauge the severity of the threat of a swine influenza pandemic face many important knowledge gaps.
Even the death toll from the outbreak, which is thought to have begun more than a month ago in Mexico, and has now spread to several continents, is open to question.
Some 150 people have died in Mexico but the number of cases, dead or alive, that have actually been confirmed in the laboratory is much lower at 26 – which means there is little data available for scientists attempting to assess the virus.
Sustained transmission
Similarly little is known about the epidemiology of the virus. On Monday the WHO increased its influenza pandemic alert level from phase three to phase four, indicating that they believe 'sustained' human-to-human transmission is occurring. But there is much more to learn about how the virus is transmitted.
"We don't really know the mortality rate, we don't really know which age groups are affected," says Sandra Mounier-Jack, lecturer in health policy and expert in pandemic preparedness at the London School of Hygiene and Tropical Medicine in England.
"We don't know the cause of death – I think that's really important, what are people dying of? Until we have more epidemiological information it's very difficult to make any kind of judgement [about pandemic potential]."
Jonathan Read, lecturer in infectious diseases at the University of Liverpool, also in England, said: "One of the key things from an epidemiological viewpoint would be how many cases we've actually got of this and how quickly they're building up or not. From that you can work out some key epidemiological parameters and get some estimate of whether a pandemic – or a large epidemic – is likely or not."
Incubation period
He said that there is a parameter known as R0, "which encapsulates how transmissible a disease can be between individuals. The higher that number is, the harder it is to control the disease." Finding out the R0 will help to assess how serious the threat from swine influenza is.
Keiji Fukuda, assistant director-general for Health Security and Environment at the WHO said at a press briefing on Monday that the WHO is working hard to document how transmissible the disease is, among other factors such as the virus's incubation period – how long symptoms appear after a person is infected. "We have a minimal amount of data about some of the factors," he said.
There is also conflicting data about the severity of the disease. No one outside Mexico has been confirmed dead – though there is a possible death in the U.S. – and most cases outside the country have been mild and treatable with antiviral drugs.
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.