Dengue fever

About dengue fever

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 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.

Most people in the UK who catch dengue fever have travelled to South-East Asia and India. In 2010, 406 people were diagnosed with dengue fever in the UK.

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 recently travelled to an area that is affected by dengue fever and have any of these symptoms, see your GP.

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

If your GP suspects you 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 will be sent to a laboratory for testing.

Treatment of dengue fever

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

Self-help

There are things you can do to help your recovery.

  • Rest and drink enough fluids. Your GP may suggest that you take oral rehydration therapy to help prevent you becoming dehydrated.
  • Take paracetamol to help relieve your pain and reduce your fever. Don’t take aspirin 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.

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 with 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 and around urban areas). Try to remove such sources of water or cover them up.

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.

Can I catch dengue fever from another person?

Answer

You can't catch dengue fever from another person just by being in close contact with them. Very rarely, dengue fever can be passed on through organ transplants, blood transfusions or from an infected mother to her unborn child.

Explanation

Dengue fever is passed on through the bite of an infected Aedes mosquito. Although you can't catch the disease directly through being in close contact with another person, it can be spread more easily by mosquitoes when people live in crowded conditions. Some evidence has shown that the virus may be able to pass from pregnant, infected mothers to their unborn children, but this is very unlikely to happen. If you're pregnant and think you may have dengue fever, see your GP for advice.

If you have dengue fever, you should take extra care to avoid being bitten by mosquitoes to help stop the spread of the disease to others. You can take the following measures to prevent getting bitten if you're infected.

  • 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 with 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 and around urban areas). Try to remove such sources of water or cover them up.

If you need more information, speak to your GP or a health professional at a travel clinic.

What are my chances of getting dengue fever if I travel to an affected area?

Answer

There are several different factors that can affect your chances of getting dengue fever. These include where you're travelling to, how long you're staying and what time of the year you travel.

Explanation

The number of UK travellers who get dengue has risen over the past few years. This is partly because the disease is becoming more common worldwide and travel to affected areas has increased.

It's difficult to say for certain what your individual risk of catching dengue fever is – everyone who travels to an area where the virus is present is at some level of risk. Travellers who spend a long time in areas where dengue fever is common (such as expatriates or aid workers) have a greater risk. However, even short-term visitors may still be exposed.

The best advice is to always protect yourself from getting mosquito bites if you're travelling to an affected area. 

What concentration of DEET should I use?

Answer

This depends on the amount of exposure to dengue fever you're likely to have and the type of protection from mosquito bites you prefer.

Explanation

Products containing DEET are available in several different concentrations – the higher the concentration, the longer the duration of protection. Concentrations of 20 percent DEET have been shown to provide about one to three hours of protection and higher concentrations provide longer-lasting protection. However, the duration of action appears to level off at a concentration of about 50 percent. This means that concentrations above 50 percent don't give you any significant added benefit, so it's generally not necessary to use products of a higher concentration than this.

The use of DEET-containing products isn't advised for babies under two months. DEET-based products are considered safe if you're pregnant or breastfeeding; however, it’s advisable to stick to those with a concentration no greater than 50 percent.

You should always use any DEET-containing products according to the manufacturer's instructions, especially since some manufacturers will advise about their own age restrictions.