Dengue fever is a mosquito-borne infection, which annually affects about 20 million people.
It is also nicknamed "break bone fever".
About 24,000 people worldwide die from dengue each year.
It is now endemic in more than 100 countries in Africa, Southern America, the Eastern Mediterranean, South-east Asia and the Western Pacific.
Dengue fever has symptoms which can be very similar initially to flu.
Most people who get it will suffer from headaches and fever. Some get rashes, aches and pains and their symptoms usually last for two or three days.
An infected person can feel tired for up to three months, but will not usually need treatment.
It particularly affects young children and adults, but is rarely fatal.
But there is one form of the disease, dengue haemorrhagic fever (DHF) that can be a fatal complication.
DHF is often characterised by a high fever, a bleeding and often enlarged liver and in the most severe cases circulatory fever.
Unlike most mosquitoes, the Ades species, which transmits Dengue fever bites during the day.
Travellers in infected areas should protect themselves during the day by wearing long-sleeved shirts and trousers.
Travellers should also use insect repellents and mosquito coils.
There is currently no vaccine for the disease.
Travellers who get dengue fever are advised to get plenty of rest and to seek medical help if their condition worsens.
But people who have got the disease once should find that they are unlikely to get reinfected within the year.