The dengue outbreak began in November last year.
According to the Ministry of Health, there were 290 cases from January to June, with the majority occurring in the capital.
Last month there were 106 cases alone.
Nearly half the dengue victims are people aged between 10 and 29 years, with more males affected than females.
The state government is undertaking an aggressive cleanup of Koror, aiming to remove breeding sites for mosquitoes.