WHO official Dr Jonathon King said that there had been a resurgence in the disease and it had been found in children.
Known in Samoan as mumu, filariasis is characterised by massive swelling of the legs.
Dr King said that because the disease is spread by mosquitoes, they aim to piggy back on vector control programme that are now being done in the territory to stop the spread of dengue, zika and other mosquito borne illnesses.
He said they were planning to have a mass treatment campaign similar to one carried out in American Samoa a number of years ago.
