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CHP investigates confirmed case of dengue fever
     The Centre for Health Protection (CHP) of the Department of Health (DH) is today (August 6) investigating a confirmed 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.

     "As the patient had both travel history and local movements during the incubation period (IP), it cannot be ruled out at this stage that the case was locally acquired. As a precautionary measure, we are working closely with the Food and Environmental Hygiene Department (FEHD) to assess and prevent any possible spread of infection," a spokesman for the CHP said.

     The female patient, aged 60 with good past health, developed fever, myalgia, red eyes and skin rash between July 29 and August 1. She consulted two private doctors in Central on July 31 and August 2 respectively and was admitted to a private hospital on August 4. She is now in stable condition.

     Her blood specimen tested positive for dengue virus NS1 antigen and dengue virus IgM antibody upon testing by the CHP's Public Health Laboratory Services Branch today.

     Initial enquiries revealed that the patient lives in Caine Road, Central and visits the Hong Kong Zoological and Botanical Gardens regularly. She had travelled alone to Guangzhou on July 25. She recalled mosquito bites in both the Gardens and Guangzhou.

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

     "Upon notification and laboratory confirmation, the CHP immediately commenced epidemiological investigations and promptly informed the FEHD for vector investigation and mosquito control. As a precautionary measure, the CHP's investigations and health education in the vicinity where the patient frequented are proceeding," a spokesman for the CHP said.

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

     Persons who have been to the vicinity of Caine Road and the Hong Kong Zoological and Botanical Gardens with DF symptoms should call the CHP's hotline (2125 2266) for laboratory investigation or referral to hospital as appropriate. It will operate starting tomorrow (August 7) from 9am to 6pm.

     To date, a total of 69 DF cases had been confirmed this year, comprising 68 imported cases and this confirmed case. In 2015, a total of 114 DF cases had been confirmed, comprising two local cases, 110 imported cases and two unclassified cases. In 2014, there were three local and 109 imported cases.

     "We will issue letters to doctors and private hospitals to alert them to the case. We will also enhance the surveillance of suspected DF cases in collaboration with public hospitals under the Hospital Authority, private hospitals and private doctors. Early referral and prompt control are critical to prevent further local spread of DF. We have also informed the Mainland health authorities of the case," the spokesman said.

     The spokesman added that the Interdepartmental Coordinating Committee on Mosquito-borne Diseases would convene a meeting next week to review the risk assessment and local response to mosquito-borne diseases including DF, Japanese encephalitis and Zika Virus Infection.

     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 Newstips 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/Saturday, August 6, 2016
Issued at HKT 21:09
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