Outbreaks caused by four types of the dengue fever virus have increased in the past 25 years. About 40% of the world's population live in areas where there is a risk of dengue fever.
Dengue is expanding:
In 2009, dengue appeared for the first time in Cape Verde, Africa, and for the first time in 40 years in Florida, USA.
Northern Australia (Queensland) recorded their worst outbreak in 50 years.
Both Mexico and the Dominican Republic reported large outbreaks this year.