Understanding dengue fever

Dengue fever is a flu-like illness that is caused by a virus and is spread by mosquitoes. Most people with dengue fever have mild symptoms but occasionally it can be quite a severe illness.

Dengue fever, which is also known as breakbone fever, is a viral illness that is passed on by a type of mosquito called Aedes mosquito. It's found in many countries throughout the world and is particularly common in South East Asia, India, the Caribbean, South and Central America and Africa.

If you are living in or travel to one of these areas and don't protect yourself against mosquito bites, you may be at risk of catching dengue fever and other mosquito-borne infections such as malaria.

Symptoms of dengue fever

The exact symptoms you get depend on your age.

In older children, teenagers and adults, the most common symptoms of dengue are:

• a fever that comes on quickly and lasts two to seven days

• headache – but this usually isn’t severe

• muscle and joint pain

• a red rash that starts on your chest, back or stomach and spreads to your limbs and face

• pain behind your eyes

• feeling sick and vomiting

• diarrhoea

The symptoms of dengue fever usually begin between five and eight days after you get bitten by an infected mosquito. However, the illness can be so mild that you don’t notice any symptoms at all.

Young children with dengue often have a fever with a rash, but other symptoms are minor.

These symptoms can be caused by problems other than dengue fever. If you have visited an area that is affected by dengue fever and have any of these symptoms, see a doctor.

Complications of dengue fever

Dengue fever can sometimes develop into a serious, potentially fatal illness.

• Dengue haemorrhagic fever. Symptoms include bleeding from under your skin, your gums and nose. You may also vomit blood or pass blood in your faeces. Your risk of developing haemorrhagic fever increases with the number of repeated infections you have with the different types of dengue virus. This means that people who live in areas where dengue fever is regularly found are more likely to be affected.

• Dengue shock syndrome. Symptoms include severe pain in your abdomen (tummy), vomiting, feeling irritable and a sudden drop in body temperature.

If you have any of these symptoms, you must seek urgent medical attention.

Causes of dengue fever

Dengue fever is caused by a type of virus called a flavivirus, which is transmitted by infected female Aedes mosquitoes. You can catch the virus if you get bitten by an infected mosquito. Mosquitoes become infected when they bite an infected person and are able to pass on the virus for the rest of their life.

There are four different but closely related types (serotypes) of the flavivirus that cause dengue fever. Once you have been infected by one type of the virus you become immune against that type for the rest of your life. However, getting infected with one type of the virus doesn't protect you against catching one of the other three types.

Diagnosis of dengue fever

Your doctor will ask about your symptoms and examine you. You should tell him or her if you have recently travelled abroad.

If your doctor suspects you could have dengue fever, he or she may ask you to have a blood test. This is to see whether you have certain antibodies for dengue fever in your blood and will confirm whether you have the infection. Your blood tests will be sent to a laboratory.

Please note that availability and use of specific tests may vary from country to country.

Treatment of dengue fever

There isn't a specific treatment for dengue fever, but your body will usually fight off the virus in three to four days after the rash appears.

Self-help

There are things you can do to help your recovery.

• Rest and drink enough fluids. Your doctor may suggest that you take oral rehydration therapy to help prevent you becoming dehydrated.

• Take paracetamol (acetaminophen) to help relieve your pain and reduce your fever. Don’t take aspirin (acetylsalicylic acid) or ibuprofen as this can worsen any bleeding you may have. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist for advice.

Hospital treatment

If you're severely dehydrated, have severe symptoms of dengue haemorrhagic fever or your symptoms suddenly become worse, you will need to be admitted to hospital. You will need to have fluids through a drip in your arm. Most people make a full recovery if they receive appropriate treatment.

Availability and use of different treatments may vary from country to country. Ask your doctor for advice on your treatment options.

Prevention of dengue fever

At present, there aren’t any vaccines or medicines to prevent dengue fever. The only way to prevent catching it is to protect yourself from getting bitten by mosquitoes. Advice for avoiding mosquito bites is as follows.

• Wear light-coloured, loose-fitting, protective clothing that covers as much of your body as possible.

• Use an insect repellent on areas of your skin that are exposed and on your clothing – especially around loose parts such as collars or cuffs. Repellents containing a chemical known as DEET (N, N-diethylmetatoluamide) are thought to be most effective.
• Use plug-in devices, which have insecticides in them, to kill mosquitoes.

• Sleep under a mosquito net to avoid being bitten at night.

• Avoid areas where the mosquitoes breed (normally in standing water in domestic containers, around urban areas). You can also remove such sources of water or cover them to prevent access by mosquitoes.

It's most important to follow these precautions around dawn and dusk, as this is when the Aedes mosquito is most active. However, it's important to remember that the Aedes mosquito can bite at any time of the day or night, so making sure you always take the necessary precautions can help to reduce your risk of catching dengue fever.