Analysis: World forced to play a waiting game with unpredictable virus

Published on Wednesday 29 April 2009 22:41

LITTLE laboratory or clinical information is available from Mexico at present. However, based upon the news from cases outside Mexico, this outbreak appears to be caused by a somewhat mild virus in terms of its effects on humans.

The cases outside Mexico reflect a moderate infection of the lung – and recovery seems to be quite quick, following the application of antiviral treatments.

To understand the true picture, we need to find out more about what is going on within Mexico itself. It may be that in an epidemic area there may be individuals who are more susceptible to the infection.

But we don't know what the broader picture in Mexico is – for example, how many people are naturally infected with the virus?

This information would allow us to understand the mortality rate.

Until we have these figures, we won't know what is going on, because it is still very early days. It should be remembered that, at present, only seven of the numerous deaths in Mexico have been confirmed from this virus.

In Edinburgh, we have been tracing the origins and the evolution of the present strain of virus, looking at the genome of the virus found in California. We have been mapping it through the Interdisciplinary Centre for Human and Avian Influenza Research.

This work helps to identify what is new in this virus and the consequences of that in humans.

This is a pig virus which has acquired a couple of genes from swine flu virus in other parts of the world

What we are dealing with is chiefly a pig virus with the ability to infect humans.

As you might expect, pig viruses normally tend to infect pigs. Occasionally, they can infect humans, and this is a severe example of how that is happening. This is a genuine case of a virus that has evolved, so now the virus can pass directly from human to human.

We are gradually increasing our knowledge of what we are dealing with, which means researchers, governments and health workers can plan the management of this outbreak and the possibility of preparing vaccines to stem its progress.

But the situation can change very quickly. These viruses are mutating all the time, and it is possible it could become more – or indeed less – virulent.

We are in unpredictable times, and we have to wait and see how things evolve.

&#149 Professor Tony Nash is director of the Centre for Infectious Diseases at Edinburgh University.