Spotlight on measles 2010: ongoing measles outbreak in Northern Ireland following an imported case, September-October 2010.

We report an ongoing outbreak of measles with five laboratory-confirmed and four epidemiologically linked cases in Northern Ireland as at 26 October 2010. The index case was an unvaccinated non-Northern Ireland resident with subsequent genotyping suggesting that infection originated in the usual country of residence of this case. Confirmed cases include one patient with a history of two measles-mumps-rubella vaccine doses.