Dengue and severe dengue: symptoms, warning signs and prevention

Dengue is a viral infection transmitted by the bite of an infected mosquito. The NHS says the mosquitoes that carry the virus bite during the day, and that dengue is very common in certain parts of the world, including parts of Africa and Asia, Central and South America, the Caribbean, the Pacific islands and some southern areas of North America.

It is also a risk at certain times of year, spring to autumn, in parts of southern Europe, with the NHS naming Croatia, France, Italy, Spain and Madeira as places where dengue has been found. Dengue is not found in the UK, so cases here are in people who have travelled.

Severe dengue, which older texts call dengue haemorrhagic fever, is a complication in which serious symptoms such as bleeding can develop. It is uncommon, but it is the reason travellers should know the warning signs.

The NHS says dengue does not always cause symptoms. If you do have symptoms, they usually start 4 to 10 days after being bitten, and some are similar to flu.

• A high temperature.

• A severe headache and pain behind the eyes.

• Muscle and joint pain.

• Feeling or being sick.

• Swollen glands.

• A blotchy rash of flat or slightly raised spots, which can affect large areas of the body.

The NHS says some people develop more serious symptoms a few days after first feeling ill, and that the temperature may start returning to normal before these appear. This is a point at which people can wrongly assume they are recovering.

• Severe tummy pain.

• Repeatedly being sick.

• Fast breathing.

• Bleeding gums or nose.

• Extreme tiredness and restlessness.

• Blood in vomit or poo.

The NHS advises asking for an urgent GP appointment or getting help from NHS 111 if you feel unwell after travelling to a country where dengue is found, and telling anyone you speak to about your recent travel. If you have dengue symptoms while travelling, get medical advice quickly.

The NHS says to call 999 or go to A&E if you have travelled to a country where dengue is found and have symptoms of severe dengue, because severe dengue can be very serious if it is not treated quickly in hospital. It says not to drive to A&E, but to ask someone to drive you or to call 999, and to bring any medicines you take.

The NHS says there is no treatment for dengue itself, but you can ease symptoms by resting, drinking plenty of fluids and taking paracetamol to bring down your temperature and ease pain. It specifically advises against ibuprofen and aspirin, which can cause bleeding problems if you have dengue.

The World Health Organization adds that people who are infected for a second time are at greater risk of severe dengue, that the symptoms of severe dengue often come after the fever has gone away, and that people who have had dengue may feel fatigue for several weeks afterwards. It also says early detection and access to proper medical care greatly lower the fatality rate of severe dengue.

People with severe dengue need to stay in hospital until they recover, where fluid balance and bleeding can be monitored and supported. Because early severe dengue can look like a mild illness that is improving, it is wise to keep monitoring and to seek help for any of the warning signs listed above.

The NHS says people at increased risk of serious illness should consider not travelling to countries where the infection is found. This includes people who are very young or older, pregnant, have certain health conditions such as asthma, diabetes, high or low blood pressure or a bleeding disorder, or who have had dengue before.

• Wear long-sleeved clothing and trousers, particularly in the early morning and early evening.

• Use insect repellent on your skin, ideally one containing DEET.

• Close windows and doors whenever possible, or use blinds or screens.

• Sleep under an insecticide-treated mosquito net, including during the day.

• Check risks for your destination on the TravelHealthPro website.

The NHS says there is a vaccine that helps protect against dengue. It is recommended for people who have had, or might have had, dengue in the past and are travelling to a part of the world where dengue is common. Get advice from a travel clinic. The NHS adds that if you need the vaccine, you will have to pay for it privately.

Assessment of illness after travel is available through your GP, NHS 111 and hospital services, and severe dengue is treated as an emergency in NHS hospitals. Tell staff where you have been.

Pre-travel vaccination advice and the dengue vaccine itself are provided by private travel clinics, since the NHS says it is not provided free. A clinic can assess whether you meet the criteria described by the NHS, namely previous or possible previous dengue and travel to a high-risk area.