A few years ago measles seemed to be heading for the history books as the number of cases around the world was on the decline. But progress has stalled, with outbreaks of the disease currently raging in countries as diverse as the United States and Madagascar.

Between 2017 and 2018 the number of measles cases globally more than doubled, with every region in the world witnessing an increase. According to the World Health Organization there were just over 307,000 cases of measles in 2018, compared to around 137,000 in 2017.

But these numbers are likely to be a huge underestimate, says Katrina Kretsinger, medical officer for measles and rubella at the WHO.

“We estimate that fewer than 10 per cent of the actual measles cases are reported and it can be as low as three per cent. In some regions where there is good surveillance such as Europe this may represent closer to the actual number but we’re not sure,” she said.

WHO doesn’t yet have any confirmed figures for 2019 but Dr Kretsinger is confident that the upward trend will continue.