Vietnamese health officials have expressed worries that dengue fever could spread and cause more fatalities as the weather favors breeding among the dengue-carrying mosquitoes.

Officials from the Preventive Medicine Department of the Health Ministry said Friday that dengue fever has already killed 20 people in Vietnam this year and the situation could worsen in the following months.

“We have seen more dengue fever patients this year than in previous years due to changes in the weather,” Nguyen Huy Nga, deputy director of the department, said.

More than 20,000 people have been infected this year in southern Vietnam. Most of them are under 15. The number of cases is already 14 percent higher than the total number of cases registered in 2006. Last year, ten people died of dengue fever in Vietnam.

As there is no vaccine for preventing the infectious disease, Nga said the best way to avoid infection is to kill mosquitoes and keep children from being bitten.

“There has been a lot of rain in the south recently, followed by sunny days, the perfect conditions for mosquitoes to breed,” Nga said. “The whole community must join hands to kill mosquitoes.”

This is just the beginning of dengue fever season and Nga said health authorities feared more casualties would appear by September, the season’s high.