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Dengue fever is a statutory notifiable disease in Hong Kong. Approximately 10-20 cases of Dengue fever are notified each year, almost always imported from elsewhere. It commonly occurs in tropical and subtropical regions. In Hong Kong, hot summers are accompanied by heavy rainfall, providing favourable breeding grounds for mosquitoes. However, the mosquito that most commonly spreads Dengue fever (Aedes aegypti) is not found in Hong Kong. Read to learn more about the symptoms, transmission, treatment and how to prevent Dengue fever.
Dengue fever is a mosquito-borne infection caused by the dengue viruses. The dengue viruses are spread to people through the bite of an infected Aedes species (Ae. aegypti or Ae. albopictus), which has a white stripe on the back surface of its thorax and bands on its legs. The dengue viruses encompass four different serotypes: Dengue virus 1, 2, 3 and 4. Each of these can lead to dengue fever and severe dengue (known as “dengue hemorrhagic fever”).
Dengue fever may present with mild to moderate symptoms which can be confused with other illnesses. Severe cases of Dengue can become rapidly life-threatening and often require care at the hospital.
Symptoms of Dengue fever generally last 2-7 days, and the symptoms of the first infection are usually relatively mild. Once recovered, lifelong immunity to that specific serotype of the dengue virus will develop. However, cross-immunity to the other three serotypes after recovery is only partial and temporary. Subsequent infections with other serotypes of the dengue virus are more likely to result in severe Dengue disease.
Dengue fever is transmitted to humans through the bite of infective female Aedes species mosquitoes. When a mosquito bites a patient suffering from Dengue fever, the mosquito is infected and it may spread the disease by biting other people. Dengue fever cannot be spread directly from human to human.
The incubation period of dengue fever ranges from 3-14 days, commonly 4-7 days. Travelers who return from affected areas and feel unwell should seek medical help promptly and provide travel details to the doctor.
Dengue fever can be diagnosed by using the following blood tests:
Dengue is a viral infection and it is mostly self-limiting, meaning there is no specific treatment and the symptoms resolve on their own. Symptomatic treatment is given to relieve discomfort (e.g. paracetamol).
Patients with severe Dengue should be treated promptly with supportive management in the hospital, to maintain the circulating fluid volume. The mortality rate is less than 1% with appropriate and timely treatment.
Partially effective Dengue vaccines exist in some places and are used in specific populations. There is no locally registered dengue vaccine available in Hong Kong. The best preventive measure is to eliminate pockets of stagnant water that serve as the breeding ground for mosquitoes and to avoid mosquito bites.
General measures to prevent mosquito-borne disease include:
Dengue fever is caused by a virus, and there is no specific treatment or cure. Dengue fever is mostly self-limiting. Symptomatic treatment is given to relieve discomfort (e.g. paracetamol). Patients with severe symptoms should be treated promptly with supportive management in the hospital, to maintain the circulating fluid volume. The mortality rate is less than 1% with appropriate and timely treatment.
You can get infected with Dengue fever not once or twice, but multiple times, with subsequent infections being deadlier than the first. It is therefore important to follow the general measures to prevent mosquito-borne disease and the proliferation of mosquitoes.
Dengue fever cannot be spread directly from person to person. However, a person infected and suffering from Dengue fever can infect other mosquitoes, and they may spread the disease by biting other people.
This article was independently written by Healthy Matters and is not sponsored. It is informative only and not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be relied upon for specific medical advice.
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