The infection rate of the mosquito-borne disease in the northern province is 499.09 per 100,000 people, Dr Supachai Boon-Amphan, a Mae Hong Son health chief, said on Wednesday.
The highest number of cases was in the 10-14 age group, followed by the group aged 15-24. Most of those infected were students and farmers. Mae Sariang is the worst-affected district with 863 cases.
Dengue fever cases in Mae Hong Son this year have more than quadrupled (4.28 times) compared to last year.
Health officials have blamed the rise on heavy monsoon rains and waterlogged conditions that are ideal breeding grounds for mosquitoes that carry the disease.