Over 21,000 people are suffering from Dengue fever in China, making this the worst outbreak in over a decade.

Dengue fever comes in four different strains, all of which are transmitted by mosquitoes, according to Medical News Today. There are no vaccines for Dengue, however, there are some remedies for people who have a mild form of the virus.

The severity of the current outbreak is being attributed to the exceptionally hot weather and an increase of travel by the Chinese to Southeast Asia where Dengue is more commonly found by authorities  in worst-affected Guangdong province, according to The Associated Press.

While the disease isn't usually fatal, but the flu-like symptoms can be especially severe for younger victims, reports AP. 

So far there are six reported deaths in this outbreak.

Dengue fever was a huge epidemic in China for three decades from 1978-2008, cites "Dengue Fever in Mainland China" by Jin-Ya Wu, Zhao-Rong Lun, Anthony A. James, and Xiao-Guang Chen. During that time there were 655,324 reported cases and 610 deaths.