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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

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

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

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

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.

By Matt Ridley | Tagged:  rational-optimist