The Centre for Health Protection was investigating a confirmed case of dengue fever on Saturday, which doctors say might be the first locally acquired case of the year. The patient, a 60 year-old woman, was diagnosed with the disease at a private hospital and is currently in a stable condition. Mosquito infestation in Hong Kong reaches ‘alert’ level, index shows, prompting fears of dengue and Zika virus transmission The patient lives on Caine Road and works in Central and visits the Zoological and Botanical Gardens regularly. She also recalled being bitten by a mosquito on a one-day visit to Guangzhou in July and at the botanical gardens, the Department of Health said in a statement. “As the patient had both a travel history and local movement during the incubation period, it cannot be ruled out at this stage that the case was locally acquired,” a spokesman said. “As a precautionary measure, we are working closely with the Food and Environmental Hygiene Department to assess and prevent any possible spread of infection.” Dengue fever, an acute mosquito-borne infection caused by the dengue virus, can result in sudden high fever, severe headaches and joint and muscle pain. In serious cases, the disease can be potentially fatal. It normally manifests itself four to six days after infection. Hong Kong hygiene authorities carry out anti-mosquito operation after insect tests positive for Japanese encephalitis People who have been in frequent contact with the patient have not shown any symptoms so far, but have been put under medical surveillance. There have been 69 reported dengue fever cases so far this year – all but one imported, according to official figures. Last year, there were 114 cases, including two local cases. Aedes albopictus, a mosquito species that transmits dengue fever, is the same mosquito that transmits the Zika virus. An index measuring the growth in the number of such mosquitoes reached a new high in Hong Kong in July. The department warned Hongkongers to remain vigilant, while intensive preventive and control exercises are to be conducted until October. People who have visited the botanical gardens or Caine Road and show symptoms of dengue fever should call the centre hotline on 2125 2266, which will be in operation from Sunday onwards.