The number of measle cases reported worldwide in the first three months this year has tripled compared with the same period last year.
According to WHO, provisional data indicated a clear trend, with all regions of the world experiencing outbreaks.
Africa has witnessed the most dramatic rise of up to 700 per cent.
The organisation said actual numbers may be far greater, since only one in 10 cases globally are reported.
At least 800 people have died from measles in Madagascar alone since september last year.
Outbreaks have also hit Brazil, Pakistan and Yemen, causing many deaths mostly among young children.