The sickness now affects less than one percent of Tonga's population, which is the benchmark for ruling out a disease as a public health problem.
RNZI reports Tonga was cited as one of the worst-affected countries in the world in the 1970s, when a study revealed 45 percent of Tonga's population was infected.
The WHO launched a global program to eliminate the disease in 2000, but the organisation has advised Tonga to remain cautious with post-elimination monitoring over the next decade in case the disease is reintroduced.