Dengue fever cases in Thailand have nearly doubled over last year, with 70 deaths so far, the health ministry said on Monday.

Health Minister Jurin Laksanavisit instructed local health officials to eliminate mosquito larvae and encourage people in high—risk areas to wear mosquito repellent, the ministry said in a statement.

Dengue is endemic in Southeast Asia and a chronic problem during the rainy season, when storms leave puddles of stagnant water where the insects breed.

The ministry’s statement said 57,940 dengue cases were recorded from January through Aug. 20, an increase of 93.8 percent from the same period last year.

“The dengue situation is still worrying,” the statement said. It urged anyone with dengue symptoms to immediately seek medical attention.

Dengue typically causes high fever, blistering headaches and intense joint pain. The most serious form can cause internal bleeding, liver enlargement and circulatory shutdown.

Earlier this month, the health ministry called on young women not to wear fashionable black leggings because dark clothing attracts mosquitoes.

Thailand’s rainy season runs roughly from June through October. Scientists fear rising temperatures and longer rainy seasons will allow more vector—borne diseases such as dengue and malaria to flourish.

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