The effects of New Zealand's social inequality on health has been laid bare in a major study which shows the number of hospital admissions for infectious diseases has risen more than 50 per cent in 20 years.

Researchers at the University of Otago in Wellington were taken aback by the alarming increase in serious infections, which were associated with a widening wealth gap and its social effects.

Their analysis of five million hospital admissions between 1989 and 2008 found that Maori, Pacific Islanders and the poor were disproportionately represented in hospital admissions for diseases such as abscesses, cellulitis and pneumonia.

Lead author Michael Baker said the findings were surprising because infectious diseases usually fell as countries became wealthier, while non-communicable diseases (diabetes, cancer) increased.


"Instead, we found infectious diseases had risen far faster than chronic diseases. New Zealand now has the double burden of rising rates of both infectious and chronic diseases."

Dr Baker noted that while rheumatic fever had almost disappeared among Western European and North American children, it was still a serious, sometimes fatal risk to Maori and Pacific children.

Health experts responding to the paper's findings said a $24 million government initiative was now addressing rheumatic fever in schools, but its introduction was belated.

The researchers found that New Zealanders living in deprived neighbourhoods were three times more likely to suffer infection compared with those living in the most affluent areas. Those under 5 and older than 65 made up the bulk of the admissions.

Co-author Philippa Howden-Chapman said interventions needed to be developed to address the major causes of poor health, in particular reducing poverty, lowering household crowding and improving access to immunisations and other health services.

Dr Baker has suggested that a council-run warrant of fitness programme for homes could resolve some of these health issues, by addressing risk factors such as mouldy rooms.

The authors noted that the Ministry of Health presented a strategic plan to reduce the burden of infectious disease in 2001. "Our findings show a need to revisit these strategies."

The research was published yesterday in the high-profile journal The Lancet.