Family doctor



DENGUE FEVER - a patient's guide


Overseas travellers are most at risk of Dengue fever which is carried by mosquitoes. This article outlines the symptoms, treatment, and measures to prevent it.

What is it?

Dengue fever is a nasty painful condition which used to be called "breakbone fever" and it can occasionally cause death. It is well worth taking avoidance measures.

It is caused by a virus (group B arbovirus) spread by a specific mosquito "Aedes aegypti" which is different from the malaria carrying mosquito. These mosquitoes can breed in urban settings such as stored water supplies and backyard rubbish but also in forested rural areas. They fly by day but increase their biting activity in the two hours around sunrise and sunset. However, they also bite at night in lighted areas.

It usually takes 5-8 days after being bitten for symptoms to occur. This means that a traveller might be back home by the time they become ill.

What are the symptoms?

The illness can range from a mild flu-like condition to a severe aching illness with marked headache, high fever, sore eyes, backache and leg and joint pains. There is seldom a cough but sometimes a rash on the chest and inner arms with spots on the roof of the mouth. Sometimes the fever seems to settle for a day or two and then recurs. Occasionally Dengue fever can result in haemorrhages from gums, nose, bowel and into internal organs. There are four sub-types of Dengue fever and having had infection with one sub-type does not confer immunity to the others. Sometimes a second infection can be worse than the first.

How can it be prevented?

Before travelling to your destination, enquire about the risk of Dengue fever. It tends to occur in epidemics and the risk is much higher for the traveller entering a known epidemic area.

Make sure you purchase a good insect repellant before you travel. Those containing DEET (N,N-diethyl-m-toluamide) in strengths up to 30% are the best and may not be available in the country to which you are travelling.

Store insect repellant in zippy plastic bags in case of leakage in your luggage. DEET in high concentrations can be absorbed through the skin and cause side effects, particularly in young children so it is better to use 20% strength for children and avoid too many reapplications in any one day.

Apply the insect repellant first thing in the morning and repeat after swimming and later in the day.

Beware of mosquitoes inside houses and at night when lights are on.

Cover as much bare skin as possible with clothing during the hours of increased biting activity around dawn and dusk. It is better to wear loose clothing as mosquitoes can bite through tight-fitting clothes.

There is no vaccination available as yet although research is in progress.

It is important to protect children travelling with you because they can be more severely affected and are at greater risk of severe forms of the illness.

What can be done?

If you do contract symptoms suggestive of Dengue fever (sudden onset of high fever, severe headaches, joint and muscle pain, nausea, vomiting and rash) seek medical advice early. The rash appears 3-4 days after the onset of fever. A blood test can detect the presence of the virus or antibodies. The illness may last 10 days to 4 weeks.

Treatment consists of rest, increased fluids and pain relief such as paracetamol. Rarely a transfusion of platelets (one of the blood cells) can be needed if they drop to dangerously low levels.

Avoid using aspirin and non-steroidal antiinflammatory drugs because of the tendency to haemorrhage.

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