Tuesday, August 25, 2015
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Matt Ridley is the author of provocative books on evolution, genetics and society. His books have sold over a million copies, been translated into thirty languages, and have won several awards.

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Why health panics are so often wrong

Antibiotics, flu and evolution

Let nobody accuse professional healthcare officials of being unproductive. They diligently produce what they are good at producing -- dire warnings of disaster.

There have been Ebola virus, Lassa fever, swine flu, bird flu, swine flu again, SARS, the human form of mad cow disease, and many more such scares. Every single one proved exaggerated -- greatly, vastly so.

To add insult to injury, when each scare fails to materialise, officials close ranks and congratulate themselves on averting it. The latest example is Britain's insulting official review of the swine flu fiasco, as described by Michael Fitzpatrick in Spiked:

The independent review of the UK response to the 2009 pandemic carried out by the former Welsh chief medical officer, Dame Deirdre Hine, concludes that 'overall the UK response was highly satisfactory': 'The planning for the pandemic was well developed, the personnel involved were fully prepared, the scientific advice provided was expert, communication was excellent, the NHS and public health services right across the UK and their suppliers responded splendidly and the public response was calm and collaborative.' Splendid!

Remember this was after spending an estimated £1.2 billion of your and my money on something that lost of us thought would prove a non-event from the start. Such complacency is infuriating.

The latest scare is an antibiotic resistant strain of bacterium called `New Delhi Metallo-beta-lactamase 1-positive'. It is said to be spreading among 'medical tourists' travelling to India for cosmetic surgery, and it presages the end of civilisation, according to Tim Walsh in Lancet Infectious Diseases last week:

In many ways, this is it. This is potentially the end. There are no antibiotics in the pipeline that have activity against NDM 1-producing Enterobacteriaceae.

Antibiotic resistant strains of bacteria have been a threat for decades and these apocalyptic cries of wolf are getting tiresome. Resistance is an evolutionary phenomenon. We expose billions of bacteria to intensely strong selection pressure in a tempting environment (hospitals, with a procession of patients with open wounds in shared rooms) and -- behold -- we select for strains that thrive on our antibiotics. So we invent new antibioitics and the arms race continues.

Cvilisation does not end, for three reasons. First, we keep inventing new antibiotics. Second, we get better at hygiene. Remember, it was antiseptic practice that first made hospitals safe place to be ill, not drugs. So even if the supply of new antibioitcs does dry up, as we have been told for decades it will, we need not be back to medieval levels of disease, just early 20th century levels. Third -- and here is a fact no journalist ever, ever remembers to pass on to readers -- antibiotic resistance goes away if you stop using the antibiotic.

When you take the selection pressure that selected for a trait away, the trait gradually vanishes -- especially if the trait is energetically expensive, as antibiotic resistance is for bacetria. For example, here's a report from the literature:

Precipitous declines first in the numbers of isolates with high-level resistance (from 31% to 4%) and then in those with low-level resistance (from 26% to 10%) accompanied prescription control.

and here's the title of a paper published last month:

The Decline of Pneumococcal Resistance after Cessation of Mass Antibiotic Distributions for Trachoma

If you stop using an antibiotics, resistance will gradually decline. Surely we can recruit evolution to our cause in our arms race. That is to say, we can accelerate the decline by ingeniously setting up the selection pressure so that resistant strains die out. I don't know how -- we need to somehow reward bacteria for being susceptible. Have a secure place in each hospital where we breed the darned things and let them out to compete with their resistant conspecifics? Sounds weird, I admit, but we need more health professionals to start understanding evolution so they can think their way to solutions.

If health officials learned just a little about evolution they might also be less panicky and financially profligate when confronted with flu scares. In normal times and normal societies, flu strains MUST evolve towards low virulence, because in victims who are still leading normal lives, they will encounter more new victims. That is true of all casual contact diseases (hence the mildness of all colds), though not of insect-borne, sexually transmitted or water-borne diseases -- which often thrive when their victims are immobilised and moribund. The peculiar conditions of first-world-war field hospitals, with nurses moving between the injured and huge fresh supplies of injured people, undoubtedly selected for an unusually virulent strain on flu. In a strain spreading in normal society, that will not happen.