The Centre for Health Protection (CHP) of the Department of Health (DH) was yesterday (August 29) investigating a local case of dengue fever (DF), and hence again urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.

     "Further to the first DF case suspected to be locally acquired this year reported on August 6, we are conducting extensive investigations with the Food and Environmental Hygiene Department (FEHD) to ascertain if both cases are linked with a view to controlling the possible spread," a spokesman for the CHP said.

     The female patient, aged 79 with underlying illnesses, developed skin rash about two weeks ago, followed by malaise . She attended Queen Mary Hospital (QMH) and was admitted on August 25 and discharged on August 27. She has all along been in stable condition.

     Testing of her blood specimen by the CHP's Public Health Laboratory Services Branch yesterday night confirmed dengue virus infection and she was then readmitted to QMH for management.

     Initial enquiries revealed that the patient lives in Shelley Street, Central and often visited the Hong Kong Zoological and Botanical Gardens. She had no recent travel history.

     Her home contacts have remained asymptomatic so far and have been put under medical surveillance.

     "The CHP immediately commenced epidemiological investigations and promptly informed the FEHD for vector investigation and mosquito control. Investigations and health education in vicinities where the patient frequented are proceeding," the spokesman said.

     Officers of the CHP will conduct site visit and field investigations by questionnaire surveys at the patient's residence for active case finding and arranging blood tests.

     Persons who have been to the vicinity of Shelley Street and the Hong Kong Zoological and Botanical Gardens with DF symptoms should call the CHP's hotline (2125 2266) for laboratory investigation or referral as appropriate. The hotline will operate from 9am to 6pm between Monday and Friday to receive enquires.

     To date, 81 DF cases have been confirmed in 2016, including 79 imported cases, one under investigations and this local case. In 2015, there were 114 cases, comprising two local, 110 imported and two unclassified cases. In 2014, there were 112 cases, including three local and 109 imported cases.

     "We will issue letters to doctors and hospitals to alert them to the case. We will also enhance surveillance of suspected cases in collaboration with public and private hospitals as well as private doctors. Early referral and prompt control are critical to prevent further local spread," the spokesman said.

     DF is transmitted to humans through the bites of infective female Aedes mosquitoes. The public are reminded to follow anti-mosquito measures when travelling to areas where DF is endemic in order to prevent DF. When a patient suffering from DF is bitten by a vector mosquito, the mosquito is infected and it may spread the disease by biting other people. In Hong Kong, the principal vector, Aedes aegypti, has not been found in recent years but Aedes albopictus is widely present so there is a risk of secondary spread of DF from imported infections.

     Dengue viruses encompass four different serotypes. The symptoms of first infection with one serotype are usually mild, but subsequent infections with other serotypes even years afterward are more likely to result in severe dengue, also known as dengue haemorrhagic fever. Severe dengue is serious and potentially fatal. Without proper treatment, the case fatality rate of severe dengue can exceed 20 per cent.

     "At present, there is no locally registered dengue vaccine available in Hong Kong. Strict environmental hygiene, mosquito control and personal protective measures remain the most effective means against DF both locally and during travel," the spokesman added.

     Travellers are urged to be alert to the dengue risk of travel destinations before departing and to take heed of the preventive measures below:
 

• Wear loose, light-coloured, long-sleeved tops and trousers, and use DEET-containing insect repellent on exposed parts of the body and clothing;
• Avoid using fragrant cosmetics or skin-care products and re-apply insect repellent according to instructions during outdoor activities;
• Before the trip, arrange a travel health consultation at least six weeks in advance for any extra measures against mosquito bites;
• During the trip, carry a portable bed net and apply permethrin (an insecticide) on it in rural endemic areas. Permethrin should not be applied to the skin; and
• After returning from dengue endemic areas, continue to apply insect repellent for 14 days.

     The incubation period of DF ranges from three to 14 days, commonly four to seven days. Anyone feeling unwell after returning from a trip should seek medical advice as soon as possible and provide travel details to their doctor.

     Members of the public should also prevent the accumulation of stagnant water and maintain good environmental hygiene:
 

• Change the water in vases once a week;
• Clear the water in saucers under potted plants every week;
• Cover water containers tightly;
• Ensure air-conditioner drip trays are free of stagnant water;
• Put all used cans and bottles into covered dustbins; and
• Store food and dispose of garbage properly.

     Members of the public are reminded to make reports to government departments via the hotline 1823 if mosquito problems are detected, and may visit these pages for more information: the DF page of the CHP and the DH's Travel Health Service, the latest Travel Health News, tips for using insect repellents, the CHP Facebook Page and YouTube Channel, and the Food and Environmental Hygiene Department's Guidebook on Control and Prevention of Mosquito Breeding.

Ends/Tuesday, August 30, 2016
Issued at HKT 0:35

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