The center for disease control and prevention in Guangzhou, capital of Guangdong province, has called on all residents to participate in preventing and controlling the spread of dengue fever in the southern metropolis.

In a statement released this week, the center required hospitals and medical institutions, especially those in areas being hardest hit by dengue, to increase the number of outpatient prescreenings and triage, as well as improve their monitoring of fever and rash cases.

Timely testing and investigations of the dengue virus NS1 antigen should be carried out to facilitate early diagnoses, reporting, isolation and treatment when suspected dengue fever cases are discovered, it said.

This year, dengue fever cases have been reported in all 11 districts of the city, which has a population of more than 17 million.

To combat the virus, local departments, property management companies, parks and environmental management units have been required to strengthen sanitation management to mitigate the conditions for mosquito and insect habitation and breeding.

Mosquito eradication work should be carried out regularly, the statement said.

Meanwhile, concrete measures should also be introduced to prevent the spread of imported cases in the coming months, it added.

Liu Wenhui, a doctor with the local CDC, said the number of dengue fever cases has risen worldwide since the beginning of this year, and the cumulative number of cases in South America and Southeast Asia has more than doubled year-on-year.

Because Guangdong has frequent foreign economic and trade exchanges and cooperation events, there is a significant risk of imported cases in the province, Liu said.

Many cities near Guangzhou have also reported dengue fever cases this year, he said.

In addition, there has been more rainfall this year, which has led to a higher mosquito vector density than in previous years.

"The city reported its first case of dengue fever on May 2 this year, one month earlier than usual," Liu said.

According to a statement released by the Guangdong Provincial Center for Disease Control and Prevention on Monday, the province reported 775 dengue fever cases from Sept 9 to 15, 73 more than the previous week.

Most of the patients were detected in Foshan (296), Guangzhou (148), Zhongshan (87), Jiangmen (44), Shenzhen (17) and Dongguan (16).

The subtropical province diagnosed 1,220 dengue fever patients in August, 987 more than in July, according to the statement.

Zhao Wei, an emergency management expert in Guangzhou and professor at the School of Public Health and Tropical Medicine at Southern Medical University, said dengue fever spreads mainly via mosquitoes. The recent rainstorms in Guangzhou have been conducive to the growth and reproduction of Aedes mosquito species, which carry the dengue virus.

"From a historical perspective, summer and autumn are usually a high-risk period for dengue fever in Guangzhou," Zhao said.

In addition to high fever, the virus usually causes severe flu-like symptoms, including headaches, rashes, lethargy and joint and bone pain. It can develop into a potentially deadly hemorrhagic fever.

Children, seniors and those with underlying chronic diseases are high-risk groups, he said.