Labour Party leader Jacinda Ardern says she will set a target to eliminate rheumatic fever if elected into government.
Ms Ardern told a crowd of about 100 at the Otara Market that rheumatic fever has become the disease of South Auckland because of poverty and over-crowded housing.
She said visiting doctors were shocked the disease existed in New Zealand.
While the government set a target in 2011 to eliminate the autoimmune disease, it failed because is has not tackled the issue of housing, Ms Ardern said.
Ms Ardern said the disease spreads when people were "huddled together, because it's warmer to sleep that way".
Ms Ardern said nine out of 10 cases are either Māori or Pasifika children - with 25 cases in Counties Manukau in the last six months.
"We have a plan to build more houses, to insulate all the rentals in New Zealand by making it a requirement that they be warm and dry."
Landowners would receive a $2000 subsidy to insulate homes and put in a source of heating, she said.
Ms Ardern told the crowd that under Labour, those on tight incomes or government support would receive a $700 grant over winter to keep their house warm.
Tax was also on the agenda, with Ms Ardern repeating her pledge to say no to tax cuts and not increase income tax.
"We'll deliver a families package that means 70 percent of our low income workers will be better off under Labour."