Thirty-five people have died in the past year from measles outbreaks across Europe, the World Health Organization has warned.
It described the deaths – which can be prevented with vaccination – as an “unacceptable tragedy”.
A six-year-old boy in Italy was the latest to die from the infection. More than 3,300 measles cases have been recorded in the country.
The most fatalities – 31 – have been in Romania.
But there have also been deaths in Germany and Portugal since June 2016.
Dr Zsuzsanna Jakab, the WHO regional director for Europe, said: “Every death or disability caused by this vaccine-preventable disease is an unacceptable tragedy.
“We are very concerned that although a safe, effective and affordable vaccine is available, measles remains a leading cause of death among children worldwide, and unfortunately Europe is not spared.
“I urge all endemic countries to take urgent measures to stop transmission of measles within their borders, and all countries that have already achieved this to keep up their guard and sustain high immunisation coverage.”
Measles is highly contagious, but vaccinating 95% of the population should prevent it spreading.
Germany is looking at tightening the law on immunisations.
And the government in Italy is pushing for children to be vaccinated against 12 common illnesses before they can enrol for state-run schools.
Prime Minister Paolo Gentiloni blamed a decrease in vaccinations in part on a “spread of anti-scientific theories”.
A lingering false belief that the measles, mumps and rubella (MMR) jab causes autism is largely to blame, despite the claims being disproven and the doctor who made them being struck off.
In the meantime, gunmen shot dead eight people, including at least one child, in a house in Thailand after holding them hostage, police said on Tuesday, a rare incident in a country where although guns are common, such mass shootings are rare.
The eight were killed in the southern province of Krabi, which is a popular beach destination, after the gunmen stormed the house late on Monday and held the inhabitants hostage before shooting them, police said.
Three people were wounded.
Police said they believed the motive was some kind of personal dispute.
“They were found this morning. Eight people died, three were injured. They were all found at the house,” Manat In-prom, an officer at the Ao Luk police station in the province, told Reuters.
“We believe there were five or six criminals.”
Thailand has a high rate of gun ownership and many people carry guns for their self-protection but such mass shootings are very rare.
According to the Interior Ministry, there are 6.1 million registered firearms in the country of 67 million people. But there are also many unregistered guns in circulation.
According to 2016 data from the University of Washington, Thailand had the highest reported rate of gun-related deaths out of 10 countries in Asia, about 50 percent higher than the Philippines, which came second on the list.