Measles in the United States, 2008

Measles is a highly infectious viral disease. Before the measles vaccine program, 450 deaths and 48,000 hospitalizations occurred annually from measles in the U.S. Due to high vaccination coverage, measles was declared eliminated from the U.S. in 2000. However, in 2008, 140 measles cases were reported from 19 states, the highest number since 1996. We reviewed the epidemiology of measles cases reported to the Centers for Disease Control and Prevention throughout 2008 to examine potential explanations for the increase. Seventeen (12%) case-patients, including six children too young for vaccination, were hospitalized. Case-patients ranged in age from 5 months to 71 years; 20 (14%) were aged <1 year, 28 (20%) were 1-4 years, and 59 (42%) were 5-19 years. Of the 127 U.S. residents with measles, 116 (91%) were unvaccinated or had unknown vaccination status, 4 (3%) had one dose, and 7 (6%) had 2 doses of MMR vaccine. Among the 116 unvaccinated U.S. residents with measles, 18 (16%) were ineligible because of age. Of the 98 vaccine-eligible case-patients, 67 (68%) were unvaccinated because of philosophical or religious beliefs. Approximately 90% (126/140) of cases were import-associated, including many from the World Health Organization European Region. The 2008 U.S. measles upsurge was characterized by spread from imported cases and a high proportion of cases in persons claiming vaccine exemptions. With large measles outbreaks in Europe and elsewhere, and unvaccinated persons clustered geographically in the U.S., imported virus and subsequent spread continue to remain a risk for further U.S. measles outbreaks.