(Acknowledgement: Pest Control Advisory Section, Food and Environmental Hygiene Department)
What is Dengue fever?
Dengue Fever is an acute mosquito-borne infection caused by the dengue viruses. The dengue viruses encompass 4 different serotypes. The incubation period ranges from 3 to 14 days, commonly 4 to 7 days. Dengue fever is clinically characterized by sudden onset of high fever, severe headache, pain behind the eyes, joint and muscle pain, loss of appetite, nausea and rash. Some infected people may not develop apparent symptoms, and some may only have mild symptoms like fever, e.g. young children may exhibit a milder non-specific febrile illness with rash.
The symptoms of first infection are usually mild. Once recovered, immunity to that serotype of dengue virus will develop but subsequent infections with other serotypes are more likely to result in severe dengue. Severe dengue is a severe and potentially fatal complication of dengue fever.
Dengue is found in tropical and sub-tropical regions around the world, and is an endemic disease in many Southeast Asian countries including Singapore, Malaysia, Indonesia, Laos, Thailand, Cambodia, Vietnam and the Philippines. Travellers visiting these places are advised to protect themselves against mosquitoes bites.
How does it spread?
Dengue virus is transmitted to human through the bites of infective female Aedes mosquitoes. This is a day-biting species with increased biting activities for 2 hours after sunrise and several hours before sunset. When a patient suffering from dengue fever is bitten by a vector mosquito, the mosquito is infected and it may spread the disease by biting other people. It cannot be spread directly from person to person.
How can you prevent it?
At present, there is no locally registered dengue vaccine available in Hong Kong. Travellers should protect themselves against mosquito bites. The personal protection measures are as follows:
- Wear loose, light-coloured, long-sleeved tops and trousers;
- Avoid using fragrant cosmetics or skin care products;
- Rest in air-conditioned or well-screened rooms;
- Use aerosol insecticide indoor and use bed nets if sleeping areas are not air-conditioned or screened.
- Use insect repellents containing DEET on exposed skin and clothings;
- Re-apply insect repellents according to instructions;
- If travelling in endemic rural areas, carry a portable bed net and apply permethrin on it as well as to clothes. Permethrin should not be applied to skin.
How is it treated?
There is no specific medication for dengue fever or severe dengue. Dengue fever is mostly self-limiting. Symptomatic treatment is given to relieve discomfort. Patients with severe dengue should be treated promptly with supportive management. The mainstay of treatment is to maintain the circulating fluid volume.
Dengue, countries or areas at risk, 2013
(with permission from the World Health Organization)