Three people died of dengue fever in Karachi and Abbottabad as another more patients tested positive for the deadly mosquito-borne disease in different hospitals of Karachi.

Two people died of dengue fever in Karachi while one became victim in Abbottabad as total of deaths reached to 17 in Pakistan.

Dengue fever, with no known treatment, is spreading fast in Asia, according to the World Health Organization (WHO).

The WHO has warned that 2.5 billion people are at risk from one of the world's fastest-emerging infections, which has "grown dramatically in recent decades."

Officials at the WHO say Asia, home to 70 percent of the at- risk population, has seen a rise in dengue mainly because of higher temperatures due to climate change, rising populations and greater international travel.