BEIJING, Sept. 23 -- The Chinese Center for Disease Control and Prevention (CDC) on Monday warned the public to stay alert about dengue exposure during the week-long National Day holiday that begins on Oct. 1.

A total of 12,336 dengue fever cases have been reported in China, with four deaths since May. South China's Guangdong Province has been hit hardest by the virus, with 11,867 cases reported as of Monday, according to the CDC.

A growing number of cases contracted abroad, especially in Southeast Asia and Africa, and rainy weather this year have contributed to the dengue outbreak, said Yin Wenwu, researcher with the CDC.

Figures from the center show that, due to high temperatures and rainy weather in Guangdong, the mosquito population is five times the normal level.

Yin suggested that those who plan to travel to south China and Southeast Asia during the holiday take precautions to guard against mosquitos and seek early medical treatment.