Health research has found those in the lower socio-economic bracket are more susceptible to infectious diseases.

Research published in medical journal The Lancet by Dr Michael Baker of the University of Otago in Wellington, shows infectious diseases has increased by 51.3 percent, while admissions for non-infectious diseases increased by only 7.6 percent.

Dr Baker says what's concerning is who's being admitted to hospital with infectious diseases.

"Whereas people in the bottom of the heap, in the poorest neighbourhoods have had an almost 100 percent increase in their hospitalisation risk."

Dr Baker says rising levels of poverty and poor housing are key contributors.

"What this means in fact is that we're now seeing 17,000 more hospital admissions each year from infectious diseases than we would expect."

AUDIO: Dr Michael Baker talks to Larry Williams

The report also shows New Zealand is lagging behind the rest of the world when it comes to the health of the lower socio-economic group.

Dr Nikki Turner of the Immunisation Advisory Centre, says it's a concern New Zealand is chasing the rest of the world.

She says New Zealand has one of the fastest growing inequality gaps in the OECD and people are being left behind.