FAQ
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| Dengue fever |
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What is dengue fever?
Dengue fever is an acute communicable disease caused by virus. The disease is transmitted through infective mosquito bites.
Which virus causes dengue fever?
Dengue fever is caused by dengue virus, which can be categorized into DEN-1, DEN-2, DEN-3 and DEN-4.
What is the mode of transmission of dengue fever?
Dengue fever is transmitted through infective mosquito bites. When a dengue fever patient is bitten by a vector mosquito, the mosquito is infected and it may spread the disease by biting other healthy people.
When will symptoms be developed after infection with dengue virus?
In general, it takes about 3 to 14 days for symptoms of dengue fever to show up after infection.
hat may be the symptoms of dengue fever?
The symptoms may include high fever lasting for 3 to 5 days, severe headache, muscle and joint pain, pain behind eyeballs, nausea, vomiting and skin rash.
Will a dengue fever patient display mild and therefore hardly noticeable symptoms?
Some infected people may not develop apparent symptoms, and some may only have mild symptoms like fever.
Once infected with dengue fever, what are the possible complications?
If infected, some patients may develop a severer form of the disease, dengue hemorrhagic fever (DHF), and other forms of complication.
What is DHF?
DHF is a severer form of dengue fever. The early stage is characterized by sudden fever and facial rash. The fever may last for about 2 to 7 days at temperatures as high as 40 to 41oC, leading to possible febrile convulsion. It is followed by bleeding phenomena such as skin bruise, nose and gum bleeding and in severe case, internal bleeding. If it is not detected and treated early, circulatory failure may develop.
Why only some dengue fever patients develop DHF?
When people are infected with dengue fever, only some will develop DHF. The risk factors include the type of dengue virus, age and immunity of the patient, etc. Therefore, if DHF is suspected, medical advice should be sought immediately for proper treatment.
What is the fatality rate of dengue fever?
Patients infected for the first time usually recover completely. For those suffering from severe DHF, if they are not properly treated, the fatality rate can exceed 20%. But with timely and proper medical management, the rate can be less than 1%.
For patients fully recovered from dengue fever, is a second infection possible?
There are four serotypes of dengue virus. Patients fully recovered from one particular serotype may contract the disease again if bitten by mosquitoes carrying a different serotype of dengue virus.
What are the differences between first, second and third infection?
The symptoms of first infection are usually mild. Once recovered, immunity to that serotype of dengue virus will develop. But second and third infections with other serotypes of virus are more likely to result in severe DHF. The symptoms are severer than those of first infection with a higher fatality rate.
What should be done if I suspect that my family members or I have dengue fever?
You should immediately consult medical practitioners who will carry out appropriate examinations and tests according to the conditions of your family members and you for a diagnosis.
How is dengue fever diagnosed?
Symptoms of dengue fever at the early stage of onset are similar to those of many other viral infections, it is therefore difficult to confirm the diagnosis according to clinical symptoms alone. Medical practitioners will usually take blood samples from the patient for laboratory tests on dengue virus or its antibody.
What is the treatment for dengue fever? Will there be any residual defect?
At present, there is no specific cure for dengue fever. Treatment is mainly supportive and relieving in nature. If treated early, patients will usually recover completely.
Will one develop dengue fever if bitten by Aedes albopictus?
Only bites by Aedes albopictus infected with dengue virus can transmit the disease. The appearance alone cannot tell whether the mosquito carries the virus and we should therefore take good precautionary measures to avoid mosquito bites.
What are the preventive measures against dengue fever?
The best way to prevent dengue fever is to guard against mosquito breeding and mosquito bites by clearing any accumulation of water at households, schools, workplaces and nearby areas.
- Against mosquito breeding:
- dispose of all used cans and bottles in dustbins with cover
- change water for plants at least once a week, leaving no water in the saucers underneath flower pots
- cover tightly all water containers, wells and water storage tanks
- keep all drains free from choke
- top up all defective ground surfaces to prevent the accumulation of stagnant water
- Against mosquito bites:
- wear light-coloured and long-sleeved clothes and trousers
- apply insect repellent containing DEET over exposed parts of the body
- use mosquito screens or nets when the room is not air-conditioned
- Members of the public can call FEHD's hotline at 2868 0000 if they notice any mosquito breeding sites in public places.
How can travellers prevent dengue fever during their trip?
At present, there is no effective vaccine against dengue fever. Therefore, the best way to prevent the disease is to take appropriate personal preventive measures against mosquito bites:
- travellers should wear light-coloured and long-sleeved clothes and trousers
- rest in air-conditioned or well-screened rooms
- apply mosquito repellent containing DEET over the exposed parts of the body
- avoid staying in scrubby areas
For other travel health information, members of the public can visit DH's HK Travellers' Health website at http://www.info.gov.hk/trhealth.
What should be noted after travelling to areas where dengue fever is prevalent?
If falling sick on return to HK from areas where dengue fever is prevalent, travellers should seek medical advice promptly and inform the doctor of their travel history to facilitate diagnosis.
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