Jakarta – Some 669 people have died in a widespread dengue fever outbreak in Indonesia in the first five months of this year and the disease still remains a dangerous threat, Health Minister Achmad Suyudi said Wednesday.

As of May 31, some 59,321 people had been infected with the mosquito-borne disease and 669 of them had died, he said.

Dengue fever is an annual rainy season hazard for Indonesians. But the number of infections so far this year is an 18 percent rise over the whole of last year, Suyudi said.

"Dengue fever still poses a dangerous threat to society but we have prepared public health service teams," he told reporters.

Samples taken from infected patients showed that most of them contracted the most dangerous type of the disease, Suyudi said.

He said the government is trying to bring the death rate below one percent but the public should continue to keep surroundings free from pools of water, where mosquitoes breed.

The ministry also warned that a malaria outbreak had hit three provinces, Riau and Aceh in Sumatra island and West Java, and killed 11 people.