The number of dengue fever cases has soared in many localities in Vietnam, the health ministry has warned.

In Hanoi, about 1,537 patients were recorded from early this year to September 6, or 3.5 times the count of the same period last year, according to Dr. Nguyen Nhat Cam, director of the Hanoi Preventive Health Center.

Such a situation has made the capital one of the six localities hit the hardest by the disease so far, Dr. Cam said.

Of the total number of patients, 633, or 49.4 percent, were recorded in August alone, the doctor said.

The disease has now spread to 29 out of 30 districts and towns of the capital city, he said, adding that high numbers of patients have been recorded in such districts as Thanh Tri, Hoang Mai, Hai Ba Trung, Ha Dong, Dong Da, Ba Dinh, Thanh Xuan, and Hoai Duc.

In Ho Chi Minh City, 8,157 people were hospitalized for dengue treatment in the January-August period, 61 percent higher than the same period last year.

The number of patients has risen sharply since the beginning of September, the municipal Preventive Health Center said.

Both Children’s Hospitals 1 and 2 have reported increased numbers of dengue patients over the past several months.

In the southern province of An Giang, the number of patients hit 1,350 at the end of last month, up 88 percent year on year.

Another southern province, Tien Giang, also saw the number of dengue patients surge 60 percent in the January-August period compared to a year earlier.

Meanwhile, health authorities in Can Tho City, located in the Mekong Delta, reported a year-on-year increase of 28 percent in the number of patients during the same period.

Dengue fever cases are increasing in five districts, including Co Do, Phong Dien, O Mon, Ninh Kieu, and Thot Not.

Dr. Cam, director of the Hanoi Preventive Health Center, forecast that the dengue epidemic might worsen in the capital in the remaining months of this year, as 2015 is the peak of a four-or-five-year cycle of dengue fever.

It is hotter and rainier this year than previous years, facilitating the reproduction of disease-causing mosquitoes, the doctor said.

There are no specific vaccines against dengue fever, he added.