The number of dengue fever cases in China’s southern Guangdong province has more than doubled to 219 in the past week, half of whom are still in hospital, Xinhua news agency said late on Monday.

Of the 219 people infected, mostly since June, 192 were in the provincial capital Guangzhou, a city of 10 million, Xinhua said. “They are in stable conditions and there have been no fatalities,” the provincial health bureau said of the patients, according to Xinhua.

The cases involved the least dangerous form of the virus, which is endemic to the tropics.

Dengue is carried by the Aedes Aegypti mosquito, which transmits the virus that causes fever, severe headache, joint and muscular pains, vomiting and rashes.

Chinese experts have blamed the recent hot and humid weather and inadequate anti-mosquito efforts for the outbreak.

Authorities have launched an anti-mosquito and city-cleaning campaign in the densely-populated Guangzhou.

A bigger outbreak sickened more than 1,000 people in Guangzhou in 2002 but none of those cases was fatal, local media said.

Small-scale outbreaks of dengue fever have been reported occasionally in Guangdong and the southeastern province of Fujian since the 1990s, Xinhua said.