Press Release

Prevention and control of dengue fever

20 April 2015

The Controller of the Centre for Health Protection (CHP) of the Department of Health (DH), Dr Leung Ting-hung, visited Shenzhen this morning (April 20) and attended a meeting with Guangdong and Shenzhen counterparts on the prevention and control of dengue fever (DF) and other acute infectious diseases this year.

At the meeting, Dr Leung also shared the latest epidemiological experience of the local winter influenza season with A(H3N2) predominating. It was reaffirmed that mutual communication and co-operation are essential in combating infectious diseases while close liaison would be maintained in case notification.

"The dengue activity remains high in neighbouring areas, including popular tourist attractions in Southeast Asia. Locally, the long period of warm weather is favourable for vector proliferation and activity. With the large volume of international travel and wide distribution of vectors in Hong Kong, the risk of more imported cases and even local transmission is thus high," Dr Leung told the media this afternoon after his arrival in Hong Kong.

"Dengue viruses encompass four different serotypes. The symptoms of first infection with one are usually mild, but subsequent infections with the others are more likely to result in a serious complication, namely dengue haemorrhagic fever (DHF). DHF is a severe and potentially fatal complication. Without proper treatment, the DHF case fatality rate can exceed 20 per cent," Dr Leung explained.

Neighbouring and local epidemiology

Regarding Southeast Asia, by mid-April 2015, 30 890 DF cases were recorded in Malaysia this year, 16 328 in the Philippines, 7 281 in Thailand and 2 445 in Singapore. Turning to neighbouring areas, 163 were reported in Taiwan, 24 in Guangdong, one in Macau and 61 in Japan.

Reviewing 2014, surges in DF were noted in Guangdong and Taiwan, respectively from 2 894 in 2013 to 45 189 in 2014 (15.6 times) and from 860 to 15 732 in the same period (18.3 times). In Guangdong, the cumulative number increased from 2 175 on September 11, 2014, to 45 171 in the week ending December 14, 2014, and the major burden was in Guangzhou. In Taiwan, 98 per cent were local cases and most were in Kaohsiung.

In Hong Kong, as of April 16, 2015, a total of 23 DF cases were confirmed this year and all were imported, including six from the Philippines, four from Indonesia and three from Malaysia. In 2014, there were three local and 108 imported cases. In 2013, 103 cases were filed and all were imported. Prior to the three local DF cases in 2014, four local cases were recorded in 2010. No deaths were reported in the past decade.

Prepare for rainy season

Dr Leung said, "We are very concerned about the three local cases last year. Following the recommendations of the Scientific Committee on Vector-borne Diseases last December, we have enhanced the awareness of health-care professionals on the importance of early diagnosis and strengthened public education on anti-mosquito measures. Running up to the local rainy season, we have been working closely with the Food and Environmental Hygiene Department (FEHD) and the Hospital Authority on contingency plans in case of a surge in DF and local outbreaks."

Heightened vigilance and ongoing preventive measures are warranted. The CHP has reinforced public education against DF through Announcements in the Public Interest in more channels such as private clinics and housing estates, as well as health education materials to District Councils, Healthy Cities Projects, public and private housing estates, schools and other stakeholders. A thematic DF webpage has also been set up and linked to the CHP's front page and the weekly number of DF cases has been updated and reported since last October.

"According to the World Health Organization, although clinical trials on humans for some dengue vaccine candidates are ongoing, none are now available and registered with any drug regulatory authorities. Strict environmental hygiene, mosquito control and personal protective measures hence remain the most effective means against DF both locally and during travel," Dr Leung added.

Avoid mosquito bites

Travellers should stay alert to the DF risk before departing, and 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 repellents according to instructions in outdoor activities;
• Before the trip, arrange travel health consultation at least six weeks in advance for any extra measures against mosquito bites; and
• 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 skin.

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 doctors.

Remove breeding sites

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.

The public 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 FEHD'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).