Update on dengue fever and chikungunya fever

     The Centre for Health Protection (CHP) of the Department of Health today (October 18) reported the latest number of cases of dengue fever (DF) and chikungunya fever (CF), and strongly urged the public to maintain strict environmental hygiene, mosquito control and personal protective measures both locally and during travel.
 
A. Dengue fever
 
     From October 11 to 17, the CHP recorded four imported DF cases. The patients had been to Guangdong in Mainland China (one case), Malaysia (one case), the Philippines (one case) and Taiwan (one case) during the incubation period.
 
     As of yesterday (October 17), 169 cases had been recorded this year, as compared with 126 cases recorded in the same period last year. All the cases in 2019 were imported, mainly from Thailand (32), Malaysia (25) and the Philippines (23).
     
     The CHP has been closely monitoring the latest DF situation in neighbouring and overseas areas. DF is endemic in many tropical and subtropical areas of the world. According to the World Health Organization, some Asian countries are experiencing unusually high numbers of DF cases for this time of year. The number of cases in several countries including Malaysia, the Philippines, Singapore and Vietnam was about two to six times the number for the same period in 2018.
 
     According to the Health Commission of Guangdong Province, Guangdong is currently in the epidemic season of DF. As of September 30, 3 435 cases had been recorded in Guangdong this year, which was significantly higher than that in the same period last year (1 389 cases).  In Taiwan, as of yesterday, 522 cases (including 99 local cases) had been recorded in 2019.
 
     Detailed information on the latest DF situation in Hong Kong as well as neighbouring and overseas countries and areas this year has been uploaded to the CHP's website (www.chp.gov.hk/files/pdf/df_imported_cases_and_overseas_figures_eng.pdf). Members of the public should stay vigilant and carry out effective mosquito prevention and control measures.
     
     ​"Apart from general measures, travellers returning from areas affected by DF should apply insect repellent for 14 days upon arrival in Hong Kong. If feeling unwell, seek medical advice promptly and provide travel details to the doctor," a spokesman for the CHP said.
 
B. Chikungunya fever
 
​     From October 11 to 17, the CHP recorded one CF case. The patient had been to Myanmar during the incubation period. As of yesterday, 10 confirmed CF cases had been recorded this year, and all of them were imported cases comprising seven from Thailand and three from Myanmar.
 
     CF is a mosquito-borne disease caused by the chikungunya virus. It is clinically characterised by fever frequently accompanied by joint pain. Other common signs and symptoms include muscle pain, headache, nausea, fatigue and a rash. Joint pain is often very debilitating, but usually lasts for a few days or may be prolonged for weeks. Most patients recover fully, but in some cases joint pain may persist for several months, or even years.
 
     Chikungunya virus is transmitted to humans by mosquito bites. Although the vector Aedes aegypti is not found in Hong Kong, another vector, Aedes albopictus, is widely distributed locally. These mosquitoes can be found biting throughout daylight hours, though there may be peaks of activity in the early morning and late afternoon.
 
     The public should take heed of the following advice on mosquito control:
 

  • Thoroughly check all gully traps, roof gutters, surface channels and drains to prevent blockage;
  • Scrub and clean drains and surface channels with an alkaline detergent compound at least once a week to remove any deposited mosquito eggs;
  • Properly dispose of refuse, such as soft drink cans, empty bottles and boxes, in covered litter containers;
  • Completely change the water of flowers and plants at least once a week. The use of saucers should be avoided if possible;
  • Level irregular ground surfaces before the rainy season;
  • Avoid staying in shrubby areas; and
  • Take personal protective measures such as wearing light-coloured long-sleeved clothes and trousers and apply insect repellent containing DEET to clothing or uncovered areas of the body when doing outdoor activities.

    
     DEET-containing insect repellents are effective and the public should take heed of the tips below:
 

  • Read the label instructions carefully first;
  • Apply right before entering an area with risk of mosquito bites;
  • Apply on exposed skin and clothing;
  • Use DEET of up to 30 per cent for pregnant women and up to 10 per cent for children*;
  • Apply sunscreen first, then insect repellent; and
  • Re-apply only when needed and follow the instructions.

 
* For children who travel to countries or areas where mosquito-borne diseases are endemic or epidemic and where exposure is likely, those aged 2 months or above can use DEET-containing insect repellents with a DEET concentration of up to 30 per cent.
 
     The public should call 1823 in case of mosquito problems and may visit the following pages for more information: the DF page of the CHP and the Travel Health Service, the CF page of the CHP, the latest Travel Health News, tips for using insect repellents, and the CHP Facebook Page and YouTube Channel.