Original: The WHO says some 2.5 billion people, two fifths of the world's population, are now at risk from dengue and estimates that there may be 50 million cases of dengue infection worldwide every year.
Simplified: The WHO says some 2.5 billion people, two fifths of the world's population, are now at risk from dengue. Estimates are that there may be 50 million cases of dengue infection worldwide each year.