Of the patients, 274 were critical, compared to 31 last year, according to the HCMC Center for Disease Control (HCDC).

Within one week from June 10 and 16, the city had recorded 136 new dengue hotspots, up 13 from the previous week, the HCDC announced Sunday.

Until now, cases have been recorded in all 21 districts and Thu Duc City.

Wards and communes with the strongest increase in the number of new patients compared to a month ago are Tan Hung and Thanh Loc in District 12, Linh Xuan in Thu Duc City, Binh Chanh in Binh Chanh District, and Trung Chanh in Hoc Mon District.

HCMC authorities raised warnings about complicated development of dengue fever in late April.

The HCDC said with the southern region entering the rainy season, it is now the peak of dengue fever. It warned people to avoid being bitten by mosquitoes.

Vietnam has been trying to find an effective way to tackle dengue, one of the biggest killers of its 28 common infectious diseases. The only vaccine for it available globally is not recommended for people who have not had dengue before.

The World Health Organization says vector control is the key strategy to prevent transmission of the dengue virus.