The Centre for Health Protection (CHP) is investigating four cases of dengue fever found in Hong Kong this month.
The four patients, aged between 17 and 84, remain in stable condition in hospital after their blood samples tested positive for the dengue virus. They did not travel outside Hong Kong during the incubation period of the virus, which lasts between three and 14 days.
These are the first local cases of dengue fever this year, with all four patients developing symptoms between August 2 and August 8.
Dengue fever is a virus spread by mosquito bites, and is potentially fatal. Symptoms include fever, headache, vomiting, muscle and joint pains, and rashes.
One case involves a 17-year-old teenager from Kwai Tsing district. He developed a fever, a sore throat, and joint and muscle pains around August 7, and was admitted to Hong Kong Baptist Hospital on August 12.
The teenager frequently visits the Sai Tso Wan Recreation Ground in Lam Tin to play baseball. He told officials that the site had lots of mosquitoes, but did not recall being bitten.
The other cases involve two men and one woman aged between 76 and 84, who all had pre-existing medical conditions. They live in Kwai Tsing, Wong Tai Sin, and on Cheung Chau.
The 78-year-old man from Kwai Tsing district frequently swam at Clear Water Bay Second Beach, and recalled being bitten by mosquitoes there. The 76-year-old woman from Wong Tai Sin goes hiking in Lion Rock Park and visits a market near Fung Wong San Tsuen daily, and did not remember being bitten by mosquitoes. The 84-year-old woman who lives on Cheung Chau mainly stays at home and did not recall getting any bites.
A CHP spokesperson said the centre was coordinating with various government departments to follow up with their investigations and step up measures to improve mosquito control.