The answer is they all brought an unwanted souvenir back from Europe and shared it with those around them. Measles.
These cases are just the tip of the iceberg. Europe’s failure to get a grip on measles is causing serious illness not just at home but abroad – even in places where home-grown measles cases are a thing of the past.
It should be a source of international shame. The thousands of cases recorded across the continent are jeopardising Europe’s measles elimination targets and delivering the disease to the doorsteps of countries where it has been wiped out.
Despite some signs of improvement in overall measles cases in Europe, this year has already seen a major outbreak in the UK, an epidemic in the Dutch Bible belt, and thousands of cases in each of Romania and Ukraine.
The US has been measles-free since the year 2000 – except for cases imported from countries where the disease still circulates. (Similarly, the US Centers for Disease Control issued a travel warning for those visiting Poland given the 36,000 cases of rubella reported there since the beginning of 2013).
In a globalised world where international travel for business and pleasure are common, staying measles-free will be a challenge for the US until Europe gets the disease under control.
The myth of measles as a disease that only affects children has been categorically put to bed in the wake of the UK outbreak where teenagers and young adults were worst affected. Many of the cases imported to the US are reported in American students and adults who travel to Europe, and in young people from Europe visiting the US.
The WHO in Europe has described immunisation as a “social responsibility”, suggesting that we should be vaccinated in order to protect ourselves and to protect others. That idea should extend not just to our own communities, workplaces and schools, but to our neighbours and trading partners.
Europe has a responsibility to keep measles under control around the world.