An infectious disease expert wants an end to the ban on New Zealanders donating blood because they lived in the UK at the time of mad cow disease epidemic.

The illness caused Creutzfeldt-Jakob disease (vCJD) in humans who could potentially pass the infection on through blood transfusions.

New Zealand excludes potential blood donors who lived in the United Kingdom, France or the Republic of Ireland for six months or more between 1980 and 1996.

Massey University infectious disease ecologist David Hayman says there are currently no known cases in the world.

"There's a large cohort of people in New Zealand who could potentially give blood but are excluded."

The study estimated 10 per cent of New Zealand's active blood donors are excluded, contributing to periodic shortages of some blood products.

"So given, we've got issues around blood supply and this would make more people eligible to give blood," says Hayman.

The estimated risk associated with the group donating blood was extremely low, he says.

"We estimated around one in a billion."

Cases of vCJD peaked 23 years ago in 2000 and have since declined, with no new cases since 2019.

Only three confirmed cases were ever linked to a blood transfusion.

Australia and America lifted their deferrals in July and November 2022 respectively.

The NZ Blood Service says it's aiming to follow suit, however, a number of steps need to be undertaken before the criteria could be changed.

-Krystal Gibbens/RNZ.