THE RETURN OF INFECTIOUS DISEASES

With measles, plague and cholera all rearing their heads again, are we seeing an unprecedented level of disease re-emergence? And what would it take to start another pandemic?

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The first quarter of this year has heralded outbreaks of measles in the US and the UK; a global shortage of the cholera vaccine; and even a case of bubonic plague for the unlucky owner of an infected cat in Oregon. Infectious diseases we thought were long gone are resurfacing, thanks in part to global conflict, international travel and climate change. But how much disease re-emergence is normal?

To find out, we spoke to Paul Hunter, Professor in Medicine at University of East Anglia's Norwich Medical School.

HOW NORMAL IS IT FOR DISEASES THAT WE THINK ARE GONE TO COME BACK?

The issue is whether they've actually gone or not. A lot of infections that were common once and still spread within society can come back with force in the future. Globally, we typically see one or two significant emergences or re-emergences every year, on average.

For many of the classic infectious diseases that seem to re-emerge, they've probably been around pretty much the whole time. Re-emergence is usually more on a regional level, such as when cholera spreads into an area that it's not caused problems in for decades.

IS IT POSSIBLE TO FULLY WIPE A DISEASE FROM THE FACE OF THE PLANET?

We did it with smallpox. We thought we might do it with poliomyelitis too, although it's not looking good. So generally, no, we don't expect to eradicate most infections. Once the infection spreads, globally and through society, you can manage and control it, but they're almost impossible to eradicate.

With smallpox, the vaccine was highly effective. There was also a lot of will to get rid of the disease and we could diagnose it fairly easily so you could quickly tell whether it had spread. Nowadays, there are a few problems. Many infections are infectious before somebody gets sick.