Palau and Wallis and Futuna have eliminated lymphatic filariasis as a public health problem.
Also known as elephantiasis, the mosquito-borne disease can lead to permanent disfigurement and disability.
The World Health Organisation said the elimination came after nearly four decades of mass treatment and monitoring programmes.
The director of Wallis and Futuna's health agency, Etienne Morel, said it was an enormous achievement, as half the territory's population was affected by the disease a century ago.
Lymphatic filariasis remains endemic in American Samoa, Fiji, French Polynesia, Kiribati, Federated States of Micronesia, New Caledonia, Papua New Guinea, Samoa and Tuvalu.
American Samoa is in the midst of a mass medication campaign to eradiciate the disease.
Authorities are trying to get 80 percent of the population - or about 46,000 people - to take the annual dose of medicine, which clears the parasite from the bloodstream.
Two weeks in, 10-thousand people have been vaccinated.
The US Centers for Disease Control and Prevention's Kim Won said it was important for people to get involved.
"These types of programmes are going on in more than 70 countries worldwide and more than a billion people are treated with these same medicines," Dr Won said.
"So I think that we have a real opportunity to prevent this disease from impacting the lives of all the people in American Samoa."