Health authorities in Wallis and Futuna say 39 people contracted dengue in the first four months of this year.
The number of infections is higher than in all of last year when 30 cases were recorded.
Dengue type 1 had been present for several years but last year the territory recorded an outbreak of dengue type 2.
In November, Wallis and Futuna declared a dengue epidemic, raising concern it could reignite the disease in New Caledonia where the previous outbreak had affected 3800 people.
Air links between the two French territories have been suspended since mid-March in an effort to halt the spread of Covid-19.
Wallis and Futuna is the only French-run territory which has been spared the virus.
New Caledonia recorded 18 Covid-19 cases, the last of which more than a month ago.