The wet season and erratic weather changes are raising the likelihood of outbreaks of dengue fever, a disease spread by mosquitoes, said the General Department of Preventive Medicine.
The department said outbreaks may become serious as the wet season has arrived early, providing ideal conditions for mosquitoes to breed.
According to department reports, dengue is rapidly spreading over southern cities and provinces, with more than 1,000 dengue cases recorded per week, infecting nearly 15,000 people and killing 11 during the first seven months of this year.
The number of people to catch dengue fever during this period is 4.4 percent higher than the same period last year.
The area at greatest threat is HCM City, followed by Dong Nai and Khanh Hoa provinces and Can Tho city. Although many other areas in the south and central regions also face high threats of outbreaks.
HCM City's Pasteur Institute said that during the last few weeks, the city saw 131 dengue patients, raising the total number of cases in the city so far this year to 3,323.
Meanwhile, nearly 3,000 dengue cases have been reported in southern Dong Nai province alone, and five patients died due to the disease.
An Giang's preventive medicine centre said that the province had nearly 3,000 dengue cases, one and a half times as many as last year.
Dengue cases in Cho Moi and Phu Tan Districts and Long Xuyen city are by far the highest across the province.
Khanh Hoa Province is said to have by far the highest number of dengue cases, with 2,200 reported in the province's central region.
Southern Can Tho Province has reported nearly 500 dengue cases, which is 10 percent higher than last year's figure.
Doctor Tran Hung, director of the Preventive medicine Centre in HCM City, said that people must act to minimise conditions that help mosquitoes breed.
He said the city has spent billions of dong each year in implementing campaigns to paevent dengue outbreaks, but residents and local authorities have not taken enough action, consequently, contributing to an increase of dengue cases.
"It is more important to raise peoples' awareness on health care," said Director Cao Trong Nguong from Dong Nai's Preventive medicine Centre.