Public health doctors want a dangerous form of Strep A added to the list of diseases that have to be formally reported to health officials.
The Public Health Communication Centre said New Zealand was lagging behind other developed countries because invasive group A streptococcus was not a notifiable disease here.
Strep A is a common bacteria carried by many people but when it turns into its invasive form, it can become deadly, causing blood poisoning, pneumonia or nectrotising fasciitis.
Public health research fellow Julie Bennett said they suspected there were about 500 cases a year of invasive group A strep here but did not know for sure.
Making it a notifiable disease would mean they could keep better track of it, including genetic sequencing to identify the strains circulating.
It would also save lives, she said.
"We can identify people who are sick to make sure they get the treatment they need but we can also identify any close contacts so they can have the management that they require," she said.
That was because it would allow contact tracing measures to be put in place and close contacts could be treated if need be.
The disease was increasing around the world and many other developed countries made it compulsory to notify incidents of it, she said.