He claimed the title after winning at the Oceania Pacific Islands Triathlon Championships in Fiji on Sunday.
Curteis was a last-minute replacement for a team member who pulled out within days of leaving for Fiji.
Curteis attends Westlake Boys' High School in Auckland where he is a top runner for the school.
Fiji's Nikotimasi Croker and Christian Rokoua finished second and third to round up the men's podium.
In the women's race, Guam's Manaima Iijima was too good for the rest of the field showing her extensive experience at racing at a high level.