Dengue fever is transmitted by female Aedes aegypti and Aedes albopictus mosquitoes, also known respectively as yellow fever and Asian tiger mosquitoes. An adult mosquito can live up to two to four weeks depending on living conditions

Visually distinctive because of the white markings on its body and legs

The Asian tiger mosquito typically flies and feeds at dusk and dawn as well as during the daytime and is called a tiger mosquito thanks to its distinctive striped appearance. It is considered a potential vector for Zika and dengue fever transmission among humans

Areas at risk

Countries or areas where dengue has been reported
The contour lines of the January and July isotherms indicate areas at risk, defined by the geographical limits of the northern and southern hemispheres for year-round survival of Aedes aegypti, the principal mosquito vector of dengue viruses

How it spreads

1. A traveller is bitten by an infected yellow fever mosquito while visiting a country where dengue fever is active
2. The dengue-infected person returns to country of origin and is bitten by a local Asian tiger mosquito
3. Mosquito ingests blood with dengue virus which takes 4-10 days to incubate
4. Infected mosquito bites another person who will fall ill from dengue fever 4-10 days later

There are four strains of dengue

After being infected, humans develop immunity from the same infection but subsequent infections from other serotypes of dengue viruses are likely to result in Dengue Haemorrhagic Fever (DHF)

Confirmed cases contracted locally as of August 25, 2018

A dengue fever outbreak is declared when one, or more, locally acquired dengue cases are confirmed

Date of symptom onset (reported date)
Residential address
Local movement during incubation period

Prevention

There are currently no vaccines for dengue fever in Hong Kong but there are many ways to prevent it from spreading

Avoid accumulating stagnant water
• Leave all used cans and bottles in covered bins
• Change water plants at least once a week; make sure no water is left in the saucer
• Cover tightly all water containers, wells and water storage tanks
• Ensure air conditioner drip trays are free of stagnant water
• Keep all drains free from blockage
• Top up all defective ground surfaces

Avoid getting bitten
The mosquito is attracted by the body odours, carbon dioxide and heat emitted from humans or animals
• Wear loose, light–coloured, long-sleeved tops and trousers
• Apply effective mosquito repellent containing Deet to exposed parts of the body and clothing
• Use mosquito screens or bed nets when the room is not air-conditioned
• Place anti-mosquito devices near possible entrances such as windows
• Take additional preventive measures when hiking or going to scrub-filled areas
• Spray a surface spray in shady areas, e.g. under furniture, behind curtains, in wardrobes or cupboard

Other tips and trivia
• Prevent mosquito bites to dengue patients
• Dengue mosquitoes prefer to fly between 50-200 metres, depending on the availability of food and containers to lay eggs
• Dengue mosquitoes only live where there are people, unlike other types of mosquitoes which live or breed in swamps, creeks, rivers, bush land or mangroves
• Unlike most other mosquitoes, they are active and bite only during the daytime

Dengue Fever Hotline:
Centre for Health Protection
Tel: 2125 1122
http://www.chp.gov.hk

Source: Department of Health — Hong Kong Goverment, WHO, Department of Health-Queensland Goverment