As night falls, Adriana de Morais patrols the clubs and bars of Natal, one of Brazil’s World Cup host cities, looking for underage prostitutes and trying to get them off the streets.

As she and her team weave between revellers in this tropical city known for its nightlife, their black polo shirts, emblazoned with the emblem of the local child protection unit, stand out amid the tight mini-skirts and colorful clothing of the crowds.

An estimated 600,000 foreigners are about to descend on Brazil for the World Cup, which opens 12 June, and the authorities worry the influx will bring an increase in sex tourism and child prostitution.

“It’s a singular event that brings many people from outside, and we really worry about sexual tourism,” Morais told AFP.

No official statistics on underage prostitutes exist in Brazil. The only figure available comes from the government’s anonymous child-abuse hotline, which received…