A measles outbreak has killed nearly 1,000 children in Madagascar, providing a chilling glimpse of how rapidly the disease can tear through a country when too few of its population are vaccinated against it.

The Indian Ocean island is facing an “unprecedented” epidemic, the World Health Organization (WHO) has warned, after 66,000 people contracted since the disease the outbreak was officially declared in October.

Health workers are deeply alarmed by how rapidly measles is spreading. In just five months it has taken hold in all but eight of the country’s 114 districts.

Even more worryingly, the number of new cases is surging. Two-thirds of the 992 deaths confirmed so far have been recorded in just the past six weeks.

The the scale of the epidemic, the first in Madagascar for 15 years, is largely down the fact so few Malagasy children are inoculated against the disease.