In recent years, the number of measles cases in the United States has increased, allegedly due to increased travel to and from countries where vaccination is not widespread.<ref>[http://www.npr.org/blogs/health/2011/05/24/136618682/u-s-measles-cases-hit-15-year-high?ps=sh_sthdl]</ref> | In recent years, the number of measles cases in the United States has increased, allegedly due to increased travel to and from countries where vaccination is not widespread.<ref>[http://www.npr.org/blogs/health/2011/05/24/136618682/u-s-measles-cases-hit-15-year-high?ps=sh_sthdl]</ref> |