This is his recommendation following the recent cases of E. coli infections in young children who have visited petting farms (i.e. farms where touching and stroking the animals is allowed). E. coli is a very nasty infection, especially in young children, some of whom have had to be hospitalised. Kidney damage is one of the serious consequences of this illness.
Extract from the BBC report: "Nine children are among those with Godstone Farm-linked infections; one is due to be allowed home later on Saturday, with the others remaining in a stable condition, according to the Health Protection Agency (HPA).
Earlier this week, the HPA apologised for delays in its handling of the Godstone Farm outbreak and announced that an external investigation would be carried out."