The strain of measles responsible for the serious outbreak of the disease in the Republic two years ago is believed to have been "imported" from Africa.
A news bulletin, produced by the National Virus Reference Laboratory, says the strain responsible for the outbreak in 2000 was found to be of genotype D2, which is predominant on the sub-Saharan African continent.
The outbreak, it said, affected 1,595 children and caused two deaths. More than 80 per cent of cases occurred in the Dublin area. It said it was "significant that the measles outbreak began in an area of Dublin with a large immigrant population and low vaccination coverage".
The uptake of the MMR vaccine for measles, mumps and rubella is as low as 45 per cent in parts of Dublin. The minimum level of vaccination required to prevent outbreaks of measles and other infectious diseases is 95 per cent.
Details of the National Virus Reference Laboratory's bulletin are published in this week's Medicine Weekly. It comes a day after the head of the National Disease Surveillance Centre, Dr Darina O'Flanagan, confirmed there had been 100 cases of measles in the Republic over the past seven weeks, treble what would be expected. The outbreaks have occurred in Galway, Westmeath and in Dublin, and parents have been urged to vaccinate children.