Like many places around the world, the Pacific islands have long been plagued with the mosquito-born disease lymphatic filariasis, also known as elephantiasis. Now (as of end July 2017) the World Health Organization has declared Tonga free of it. The Marshall Islands were declared free a few months earlier, in March.
The disfiguring and sometimes fatal disease was noted by the late eighteenth century explorer James Cook in his travels in the South Seas, but it has a much longer history. It was known in Goa since at least the sixteenth century and thought to have been present in the Middle East thousands of years before.
Filariasis was present in Tahiti (French Polynesia) in 1954 when the writer H E Bates visited there (at the suggestion of the filmmaker David Lean). In the third volume of his autobiography ("The World In Ripeness", 1972), Bates tells (p. 136) how a fellow passenger in the plane that took him there was an American doctor carrying a box of giant mosquitoes that he hoped would eat the smaller local ones that are a vector for the disease. Sadly, it's still a risk there, but of the 22 Western Pacific countries and territories in the WHO's eradication programme (see p. 18 here), 4 (Cook Islands, Marshall Islands, Niue and Vanuatu) have succeeded and the work goes on.