A doctor at the Centers for Disease Control and Prevention (CDC) has told US travellers to make sure they are vaccinated against measles if they travel to Poland and Ukraine for soccer matches in early June or to London for the Olympics in July.

“Disease knows no borders. We are concerned about Americans coming back from the Olympics this summer and unknowingly infecting others,” Rebecca Martin, director of the CDC’s global immunisation division, told the newspaper USA Today (“US travelers to Olympics may bring home measles,” www.usatoday.com 19 March, 2012).

Measles was declared eliminated in the US in 2000. Most cases of measles are imported by travellers who have not been …