Cambodia registered 502 dengue fever cases in the first four months of 2015, a 67 percent rise from 300 cases over the same period last year, a health official said in a statement on Saturday.

"The incident rate is 3.1 cases out of 100,000 people," Huy Rekol, director of the National Center for Parasitology, Entomology and Malaria Control, said in the statement.

Despite the increase in cases, the mosquito-borne disease killed only one kid during the January-April period this year -- the same number as last year. The official attributed the decline in fatal rate to the improvement of treatment quality at public hospitals.

"This result shows that Cambodian people are well-aware of how to prevent themselves from dengue fever and timely send their sick children to hospitals for medical treatments," he said.

Dengue fever is a viral disease transmitted by Aedes mosquitoes. The disease causes an acute illness of sudden onset that usually follows symptoms such as headache, fever, exhaustion, muscle pain, swollen glands, vomiting and rash.

In Cambodia, the outbreak of dengue fever usually begins at the onset of the rainy season in May and lasts until October.