Howell's right shoulder, which had an off-season operation, has not recovered sufficiently for the rigours of throwing at first-class level, and he has been replaced in the Northern team by Michael Parlane (Northern Districts). Howell has recently returned to club and cricket Max play.
Cairns has been also seeking to regain fitness after a knee overuse injury and aimed to be fit for the Conference competition which begins tomorrow. But he was stiff after bowling briefly for Canterbury in its Max match last Friday and missed the Sunday game.
New Zealand Cricket's operations manager John Reid said Cairns would continue on a graduated bowling programme in the coming days with the expectation of him being able to play in the remaining three games of the series.
``It's a bit disappointing, but we don't want to risk it. He probably could not have been able to bowl 20 overs in a day,'' Reid said.
Cairns's replacement in the Southern side is Otago batsman Mark Richardson with Reid saying the team had enough bowlers.
Joining Howell is Auckland's Aaron Barnes who sustained a back injury in last weekend's Max matches and cannot bowl for two weeks. He is replaced in the Northern team by Stephen Mather.
Aucklander Kerry Walmsley who pulled a hamstring last week and missed the Max games will join the Northern team.