The first local case of dengue fever recorded for the first time in more than a year in Hong Kong indicates that undiagnosed imported cases could lead to an outbreak in the coming months, a health official has warned, while stressing that the risk was preventable.

The warning by Albert Au Ka-wing, head of the Centre for Health Protection’s communicable disease branch, came after one case was recorded in Tai Po last Thursday, in a patient with no travel history.

“The first local dengue fever case proved the existence of possibly undiagnosed cases in Hong Kong in which people were bitten by mosquitoes. They infected the mosquitoes, which then spread the virus, indicating a risk of local transmission,” Au said on a radio programme on Wednesday.

“The increase in temperature and arrival of the rainy season will create ideal breeding grounds for mosquitoes. With the mosquito-borne disease present in Southeast Asia and neighbouring areas … we cannot ignore the risk of an outbreak, but it is preventable and under control for now.”

Hong Kong has recorded 13 dengue fever cases so far this year, of which 12 were imported. The city recorded no local cases last year.

The recent case involved a 21-year-old man with no underlying health conditions, who developed a fever, headache, myalgia and a rash on April 12. He sought medical attention at Alice Ho Miu Ling Nethersole Hospital in Tai Po on April 16, according to the authorities.

The patient was admitted for treatment and is currently in stable condition. His blood sample tested positive for the dengue virus, and he reported being bitten by mosquitoes near his workplace, a road construction site near Long Yan Road in Penny’s Bay on Lantau Island.