Alarmed public health experts are calling for pregnant women to be tested twice for syphilis as cases in newborns and unborn babies increase.
The Public Health Communication Centre said it used to be very rare to see congenital syphilis - passed on from a mother to her unborn baby - but in the past five years there had been 25 infections.
Infectious diseases paediatrician Emma Best said most people were screened for the sexually transmitted disease in the first trimester of their pregnancy but some were contracting it after that.
"We think a second syphilis test in the third trimester would be helpful to detect cases and let us treat newborn babies if we know about it - or mums, even better," she said.
The disease could be treated by antibiotics during pregnancy and that could prevent it being spread to babies, she said.
Congenital syphilis could cause stillbirth, premature birth and babies could be born with syphilis symptoms like fever, an enlarged liver or a rash.
Later, babies without symptoms at birth could become deaf, or develop seizures or intellectual disabilities.
Best said it was a disease that the country should never see because it was treatable, but a rise in the number of cases in adults has now meant babies are more at risk.
Auckland, Northland, Waikato and parts of the central North Island already had third trimester testing, the centre said.
Best said Māori and Pacific woman were disproportionately missing out on screening and that needed to change.
That was partly because they were less likely to have a lead maternity carer by their first trimester so would not even get a first test.
RNZ
