The Philippines has issued a nationwide dengue fever alert after recording more than 4,000 cases in the second week of September, the health department said Wednesday.
It said it had recorded 24,689 cases of the mosquito-borne disease in all since January with 283 deaths.
The head of the National Epidemiology Center, Eric Tayag, said in the statement that he expected a sharp increase in the number of cases in September and October.
"It's during this period that we expect the disease to proliferate due to the wet weather," he said.
Public health officials earlier this year warned of a possible epidemic of dengue fever in Asia this year.
The World Health Organisation (WHO) said in July that 2007 could be on a par with 1998, when nearly 1,500 people died in Asia of the disease.
There is no known cure or vaccine to fight dengue fever, which is transmitted by a bite of the white-spotted mosquito known as Aedes aegypti.
Most of those killed tend to be children and old people who have a weak resistance to the virus, and die as a result of internal bleeding.
The early arrival of the rainy season in much of Asia has been blamed for the upsurge in outbreaks this year, experts say.