According to WHO figures, there have been more than 68,000 cases of the disease in which 553 deaths were confirmed and another 373 suspected from measles since the outbreak began in September.
Those most at risk are infants from nine to 11 months old.
The epidemic is blamed on a low immunization rate for measles across the island nation over a period of many years, according to WHO spokesman Tarik Jasarevic. The vaccination rate is estimated to be less than 60 percent, according to figures from WHO and UNICEF figures, he said.
Madagascar has launched a nationwide campaign to try to bring the outbreak under control, through mass vaccination campaigns and surveillance.