Health authorities have called for strengthened monitoring and epidemiologic research of dengue fever as south China\'s Guangdong and Yunnan provinces are seeing a spike in cases of the disease. Dengue is a mosquito-borne, potentially fatal disease that affects between 50 and 100 million people in tropical and subtropical regions every year, causing fever and muscle and joint aches. In a Friday statement, the National Health and Family Planning Commission urged local health administrations to eliminate mosquitos and their breeding places to prevent potential outbreaks while controlling existent cases from spreading. The number of confirmed dengue fever cases in a prefecture of southwest China\'s Yunnan Province had risen to 581 by Wednesday, although no deaths have been reported since the disease was first spotted there on Aug. 15. The cases include 14 originating from neighboring countries, including Myanmar, Laos and Thailand, local authorities said. The commission called on local health departments to cooperate with police, tourism and other departments in monitoring the health conditions of people returning from dengue-prevalent regions such as Southeast Asia, South America and Africa. It also called for more publicity of information on the disease to raise public awareness as well as more training for hospital staff in treating dengue fever. According to the commission, expert teams will be sent to guide epidemic prevention and control work on site immediately in case of an outbreak.