Tainan City in southern Taiwan has seen 2,152 cases of dengue fever this summer, the highest concentration of dengue cases in Taiwan.
The first confirmed case was on May 16. Four people, who were all over 70, have died, according to the city government on Wednesday.
Tainan has seen 80 percent of the island's cases of dengue, while Taipei had the highest number of people with dengue that had caught it else where, authorities said.
Dengue fever is transmitted by mosquitoes. It causes headache, fever, exhaustion, severe muscle and joint pain, swollen glands, vomiting and rash.
Residents have been urged to clear waste water in or near their homes, rooftops and construction sites, and to take precaution when traveling abroad.
