Not abiding by the constraints of species

On the cover this month you’ll find staring back at you a killer of truly grotesque stature. Responsible for nearly 30 million deaths, HIV can, at the very least, be regarded as a very successful pathogen.

But that sobering stat isn’t quite the full picture – for it only considers human deaths. While humanity has only been under attack from this immuno-assassin for around 80 years, simian immunodeficiency virus – the viral ‘originator’ of HIV – has been cutting its deadly swathe for some 32,000 years. Consequently the devastation to simian populations is orders of magnitude higher.

But should we even consider this in the same breath as the human cost? Well, yes I think we should. When it comes to the onslaught of pathogens on humankind, we cannot afford to abide by the constraints of species. We can’t sit neatly in our elevated evolutionary position resting on the crutches of modern medicine – for a virus cares not for such arbitrary constructs – if it can infect, it will infect. And as humans, we are the ultimate prize for a pathogen and its ability to spread effectively; we travel, we are social and we are very numerous.

This has been seen time and time again, most notably in recent years is the ability of avian influenza viruses to hop across the species barrier to humans. The latest of which is H7N9 which appears to have to mutated from a strain infecting wild duck species native to China.

The burning question now becomes: “Will this turn into another pandemic?” Certainly the wider public health community are worried ­– a few weeks ago more than 30 international experts gathered at the Food and Agriculture Organisation of the United Nations in Rome to discuss this very possibility. At the time of writing, more than 80 people in China have fallen ill and Chinese officials were investigating the possibility that the virus has spread from human to human.

If H7N9 proves to be successful at human infection – what then, can we do? Well the response will centre around animal health expertise, and much will be asked of the scientists in this field. It is far from easy to devise effective ways to sample birds and animals for testing in a country with some 6 billion domestic birds. Especially, say flu experts, as domestic poultry do not seem to have fallen very ill from the latest H7N9 infections, which could lead to a "silent" outbreak in China.

So then, the challenge then is set – but are animal health scientists up to the job? See All Creatures Great and Small to find out how advances in technology have armed them very well for the task in hand…