Hospital admissions for infectious diseases have jumped dramatically over the past two decades, research shows.
An Otago University study has found admissions increased by 51% between 1989 and 2008.
Lead researcher Michael Baker says Maori and Pacific people are more than twice as likely as the European population to be admitted with a serious infectious disease.
Those living in poverty have three times the risk compared to people living in the most affluent areas of the country.
Mr Baker says he is surprised by the increase, and the country must tackle a "double burden" of rising rates of both infectious and chronic diseases.
He told Checkpoint most of the increase occured in the early 1990s when there were rising income inequalities, and New Zealand was going through a period of economic reform.
Prime Minister John Key says the Government is working to address poverty related heath issues as quickly as it can.
"We're a first world country and we don't expect New Zealanders to be contracting third world diseases," he says.
The study, based on the analysis of five million overnight admissions to hospitals, shows admissions for non-infectious diseases rose by only 7%.