Dengue

Dengue fever is a disease caused by the dengue virus which is transmitted to humans via the bite of an infective mosquito. There are four different serotypes of dengue virus (DENV1 to 4) circulating in the world, including Singapore. Hence, individuals can be infected with dengue up to four times. First-time dengue infections can be severe, especially among the elderly and those with pre-existing medical conditions, and repeat dengue infections have been associated with a higher occurrence of severe dengue. Dengue haemorrhagic fever and dengue shock syndrome can be fatal. Together with the National Environment Agency (NEA), we provide regular weekly updates on all dengue cases and track dengue-related deaths in Singapore which are reported quarterly.

Dengue fever is transmitted to humans via the bite of an infective Aedes mosquito. A mosquito becomes infected after it takes a blood meal from a dengue-infected person. It becomes infective after an extrinsic incubation period of 8 to 12 days. The mosquito then remains infective for the rest of its lifespan. When a person is bitten by an infective mosquito, they may develop symptoms after an intrinsic incubation period of 4 to 7 days (ranges from 3 to 14 days). Notably, up to 75% of dengue infections are asymptomatic. Dengue fever does not spread from person to person.

• Sudden onset of fever for 2 to 7 days
• Severe headache with pain behind the eyes
• Joint and muscle pain
• Skin rashes
• Nausea and vomiting
• Mild bleeding (e.g. nose or gum bleed, or easy bruising of the skin)

If you think you have dengue fever, seek medical attention at your primary care doctor. Use mosquito repellent regularly if you are diagnosed with dengue or suspected to have dengue, to protect your loved ones and others living around you. Repellents containing DEET (N,N-diethyl-m-toluamide), picaridin or IR3535 as the active ingredient are the most effective in repelling mosquitoes.

In rare cases, dengue fever may progress to dengue haemorrhagic fever or dengue shock syndrome. These are severe forms of the infection that can result in death. Symptoms of severe dengue may include:

• Bleeding (e.g. gum or nose bleed, black stool, blood in vomit or stool)
• Persistent vomiting
• Abdominal pain or tenderness
• Restlessness or lethargy

Warning signs usually begin 1 to 2 days after your fever has subsided. If you have any of these warning signs, seek medical attention immediately. Severe dengue is considered an emergency and requires immediate medical care.

You can prevent mosquito bites by applying mosquito repellent, wearing long, covered clothing, sleeping under mosquito nets or in rooms with wire-mesh screens or air-conditioned rooms.

You should use mosquito repellents containing DEET (N,N-diethyl-m-toluamide), picaridin or IR3535 as the active ingredient, as they  are more effective and/or have longer mosquito repelling effects than  “natural” repellents that use plant-based extracts, such as citronella, eucalyptus and other essential oils. Use mosquito repellent regularly if you are living in or visiting either dengue clusters or areas with higher Aedes aegypti mosquito population.

You  should download NEA’s myENV mobile app, which provide users with updates on dengue clusters and areas with higher Aedes aegypti mosquitoe population.

Preventing the spread of dengue is also about maintaining vigilance in your environment. The Aedes mosquito has a distinctive black and white striped body, and prefers to breed in clean, stagnant water. By frequently checking and removing stagnant water from your home, you can help to prevent the spread of dengue fever. For more advice on preventing Aedes mosquito breeding, you can visit the National Environment Agency website.

The Health Sciences Authority (HSA) has approved a dengue vaccine, Dengvaxia, for individuals aged 12 to 45 years old. This is the only licensed dengue vaccine in Singapore. Dengvaxia can be useful for individual protection for persons in this age range who have been previously infected with dengue. The vaccine is not recommended for those without prior dengue infection. If you are keen to be vaccinated for personal protection, consult your doctor as to whether Dengvaxia is appropriate for you.

If you think you have dengue fever, seek medical attention immediately. Use mosquito repellent regularly if you are diagnosed with dengue or suspected to have dengue, to protect your loved ones and others living around you. Repellents containing DEET (N,N-diethyl-m-toluamide), picaridin or IR3535 as the active ingredient are the most effective in repelling mosquitoes.

There is no specific treatment for dengue fever, or its more serious forms, dengue haemorrhagic fever and dengue shock syndrome. Treatment for dengue is supportive. In more severe cases, you may be hospitalised for aggressive emergency treatment, including fluid and electrolyte replacement, and/or blood transfusions.