Press Release

Update on number of dengue fever cases

29 April 2016

The Centre for Health Protection (CHP) of the Department of Health (DH) today (April 29) 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.

From April 22 to 28, an additional confirmed imported case was recorded and the patient had been in the Maldives during the incubation period. As of April 28, a total of 33 cases had been confirmed this year and all are imported.

The CHP has been closely monitoring the latest dengue situation in neighbouring and overseas areas. Regarding popular tourist destinations in Asia, the latest figures for 2016 revealed that 15 912 DF cases have been recorded in Thailand, and 101 in Japan since January 4, 2016. A total of 7 235 cases have been recorded in Singapore since January 3, 2016, and according to the health authority of Taiwan, 372 local cases have been recorded to date in 2016. In the Americas, the latest figures indicate that 802 429 cases were filed in Brazil and 21 728 in Mexico 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, members of the public going 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," a spokesman for the CHP 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 the pages below for more information:

• The CHP's DF page (This link will open in a new windowwww.chp.gov.hk/en/view_content/38847.html);
• The DF page of the DH's Travel Health Service (This link will open in a new windowwww.travelhealth.gov.hk/english/popup/popup_dengue.html);
• The DH's latest Travel Health News (This link will open in a new windowwww.travelhealth.gov.hk/english/outbreaknews/outbreaknews.html);
• The CHP's tips for using insect repellents (This link will open in a new windowwww.chp.gov.hk/en/view_content/38927.html);
• The CHP Facebook Page (This link will open in a new windowwww.fb.com/CentreforHealthProtection);
• The CHP YouTube Channel (This link will open in a new windowwww.youtube.com/c/ChpGovHkChannel); and
• The Food and Environmental Hygiene Department's Guidebook on Control and Prevention of Mosquito Breeding (This link will open in a new windowwww.fehd.gov.hk/english/safefood/handbook_prev_mos_breeding.html).