Absence of endemic measles transmission in a highly vaccinated population from 1999 to 2008: Implications of sustained measles elimination in Taiwan

Background: Measles remains a leading vaccine-preventable cause of child mortality worldwide. The impact of vaccination programs can be seen in the increasingly low incidence of measles. However, cases of measles continue to occur in low numbers every year in Taiwan. We assessed the epidemiology of measles in Taiwan from 1999 to 2008 with a focus on domestic versus imported cases. Methods: We analyzed the data reported to surveillance systems at the Taiwan Center for Disease Control, where viral isolation was performed. Results: A total of 84 measles cases were reported from 1999 to 2008 in Taiwan with the incidence of measles varying from 0 to 1.5 per 1,000,000 people per year, peaking in 2002 and again in 2008. The incidence decreased with increasing age in both males and females. Among the 84 reported measles cases, 39(46%) originated internationally, 8(10%) were epidemiologically linked to imported cases and the source was unknown in 37(44%) of the cases. The unknown-source cases were analyzed for potential evidence of endemic measles transmission. Most of the measles cases that occurred in Taiwan from 1999 to 2008 were associated with imported cases. No endemic transmission of measles in Taiwan was identified. Conclusions: This study suggests that maintaining the high rate of vaccination coverage is needed to prevent future outbreak and sustain the elimination of measles in Taiwan. (C) 2010 Elsevier Ltd. All rights reserved.