December 01, 2009

Article at Cosmos Magazine

OPINION | Now for the Good News

We have grown blasé about infectious diseases. But fighting infections may once again deliver public health benefits not seen for a century.

By Wilson da Silva 

THERE WAS A TIME when working as a clinician or a researcher in the field of infectious diseases was both popular and prestigious. A time when governments invested in public health and communities were proud of their local hospitals.

These days, public health is seen as a cost rather than a benefit. That’s partly because there are so many more people living to a ripe old age and treatment at advanced ages requires more intervention, often using new and costly equipment, techniques and drugs. With the West facing falling birth rates and an ageing population, it’s becoming harder for governments – relying on working-age taxpayers – to fund these rising medical costs.

But we are also victims of our success. And we’ve grown arrogant. Thanks to the successful onslaught of weapons that science has made available to medicine – vaccines, improved nutrition and sanitation, and especially antibiotics – we have grown blasé about infectious diseases. Consequently, they have fallen out of favour with students and funding bodies; after all, sufferers these days mostly live in poor countries.

In 1850, infectious diseases accounted for 59% of all disease deaths in Britain; this was 13% by 1971. It’s worth noting that suppression of infectious diseases accounted for an estimated 80% of the rise in life expectancy since 1850. We got so cocky that the U.S. Surgeon-General William H. Stewart told the U.S. Congress in 1969 that “the war against infectious diseases has been won”.

Medicine in the West then turned its attention to chronic diseases such as cancer and heart disease – a mindset that has largely prevailed.

It’s ironic, then, that a growing body of evidence suggests that a whole range of chronic diseases may actually have an infectious origin. Up to 50% of people with heart disease have none of the conventional risk factors, such as high blood pressure or high cholesterol.

Could infection be the missing piece of the puzzle? Many scientists believe so. And groups around the world are hot on the trail of viral and bacterial agents that may play a role in everything from heart disease and cancer to diabetes and obesity.

When I mentioned this to a friend, she was aghast: “Great, now I get to worry about catching heart disease!” Actually, this is uniformly a good thing: if infections do play a role in a wide range of diseases, it opens the door to finding their viral or bacterial agents and – as we have done so admirably in the last century – suppress infections.

Which is great news. But if we are to make major advances, it’s clear we also need to understand the maddening complexity of the human immune system. In this, Mark Davis, a microbiologist and immunology researcher at Stanford University, thinks we are far too reliant on the ‘mouse model’ in the lab and need a Human Immunity Project to make advances clinically useful. 

What’s clear is that science is making major leaps forward in human medicine – thanks to genetics, computer modelling and advances in biochemistry and our fundamental understanding of biological systems. Even cancer is revealing its tricks, and there’s surprising new hope for allergy sufferers.

Like people a century ago, we may live to see exciting medical advances in the decades ahead; see scourges we once considered a death sentence fall away and be conquered. Let’s hope we don’t get too cocky this time.