A 3-year-old Canterbury girl is recovering in Starship Hospital after contracting a life-threatening disease while feeding a lamb.

The girl contracted an uncommon cause of infectious diarrhoea, Verocytotoxin-producing Escherichia coli (VTEC), from unpasteurised milk in a bottle she was feeding to the lamb.

The VTEC caused the girl to develop a life-threatening syndrome which affects the blood and kidneys, called haemolytic uraemic syndrome (HUS). One-fifth of children with the syndrome die.

The girl went into significant kidney failure, resulting in intensive medical care at Starship.

Canterbury Medical Officer of Health Dr Alistair Humphrey said she was now recovering well but was still expected to stay in hospital in Auckland for next few days.

"It is not clear in this case whether the child contracted VTEC E.coli as a result of drinking unpasteurised milk, or by simply touching the lamb. Fortunately, in this case the little girl is recovering."

Humphrey said the incident highlighted the need for caution around farm animals.

"Touching farm animals can be lethal. VTEC is one of several diseases carried by healthy animals," he said.

Up to 10 per cent of children with VTEC go on to develop HUS.

It was not uncommon for children to contract VTEC in spring. Humphrey said Community and Public Health were currently investigating two more possible cases.

"Spring is the time of year when stomach bugs are unfortunately most prevalent in Canterbury. Spring is a busy time on farms and in meatworks and people are in close contact with animals. Often this includes workers or visitors who don't usually deal with animals," he said.

To prevent the spread of VTEC and other infections it was important people only drank pasteurised milk and did not put their hands in their mouth after feeding or touching farm animals, Humphrey said.

"This requires parents to be very vigilant when young children are around farm animals."