From Paul Murphy
I always find it amusing when scientists express how predictable something is
after the event. Perhaps we should invent a new word: “A team of scientists has
just postdicted a raging foot and mouth epidemic.”
However, David Tilman’s statement, “Epidemic losses of livestock are . . . a
predictable outcome of high animal densities and low genetic diversity”, is a
salient one
(21 April, p 11).
It is one we should keep in mind when a genetic
engineering company inevitably announces a new engineered sheep breed that is
resistant to foot and mouth and suggests it be the base stock of our national
sheep population.
The introduction of such a breed would offer a selection pressure that would
favour any virus that could thrive in such a consistent genetic
environment—perhaps a new strain of foot and mouth. Not only would our new
sheep have no resistance to it, but the new strain would also be one that our
already flagging vaccines could not stop.
newsci@zencore.co.uk
