Update on number of dengue fever cases

     The Centre for Health Protection (CHP) of the Department of Health (DH) today (July 15) reported the latest number of cases of dengue fever (DF) in Hong Kong, and again urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.

     "In view of the relatively high dengue activity in some neighbouring and overseas areas, the public should remain vigilant. Travellers to dengue endemic areas during summer vacation should use DEET-containing insect repellents both during travel and for 14 days after arrival back in Hong Kong," a spokesman for the CHP said.

     From July 8 to 14, five additional imported cases were confirmed. The patients had been to Malaysia (two cases), Laos (one case) and India and Sri Lanka (two epidemiologically linked cases) during the incubation period. As of July 14, a total of 58 cases had been confirmed this year and all were imported.

     The CHP has been closely monitoring the latest regional and overseas dengue situation. In Asia, 22 566 DF cases have been recorded in Thailand this year, 9 530 in Singapore since January 3, 161 in Japan since January 4, and 373 local cases in Taiwan to date in 2016. In the Americas, 1 244 583 have been filed in Brazil and 34 275 in Mexico so far in 2016.

     "In Brazil, the dengue activity is high, with ongoing local transmission of Zika virus and other endemic diseases such as malaria and yellow fever. As these diseases are all mosquito-borne, travellers to Brazil should stay alert and strictly follow steps to avoid mosquito bites during the trip. Upon arrival in Hong Kong, they should use insect repellent for 14 days, and seek medical advice if symptoms develop," 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 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/Friday, July 15, 2016
Issued at HKT 15:13