Auckland Regional Public Health Service (ARPHS) said an 11th confirmed case had been identified and the person was in hospital.
All cases are linked and are among members of a Pacific church community in Auckland, said Dr Julia Peters, the regional health service's clinical director.
Health officials first issued an alert on Friday saying 10 people were in hospital.
Auckland gets around 30 cases of typhoid a year but are usually individual cases where someone has been infected overseas.
So far the source of the latest case has not been indentified.
