Dengue fever is a painful, debilitating viral disease carried by Aedes mosquitoes, and is most prevalent in tropical regions.
Symptoms include high fever, severe headaches, joint and muscle pain, nausea and vomiting. They can last for up to about 10 days.
In some cases it can be fatal, particularly to children, infirm elderly and other people with weakened immune systems.
More than 300 million people are infected annually, the World Health Organization estimates.
There is no vaccine nor specific treatment, other than hydration and certain types of pain relievers such as acetaminophen.
A small percentage of cases are haemorrhagic dengue, which can damage internal organs such as the liver and brain.
The disease is endemic to more than 100 countries, particularly during rainy seasons.
The Aedes mosquito can breed in small volumes of standing water, making it difficult to control populations, particularly in crowded urban areas.