As many as 513 cases of dengue fever have been reported in the the capital city of Hanoi so far in 2013, a 20 percent increase year-on-year, according to the municipal Department of Health (DoH).

The department has formed supervision teams to work with local authorities helping citizens cope with the disease, said DoH Deputy Director Hoang Duc Hanh.

In Vietnam, dengue fever peaks in the hot rainy months of July and August. The dengue virus is most commonly transmitted by mosquitoes.-VNA