Current US hot spots are Utah, Arizona, and South Carolina.
The case total in South Carolina related to the Upstate outbreak has now reached 76.
Last year, only 84% of children received the first dose and 76% received the second dose of measles vaccine worldwide.
The US now has almost 1,800 measles cases.
In international developments, Israel has now confirmed 10 measles deaths in children this year.
Together Mohave County, Arizona, and southwestern Utah have 201 cases.
Overall, 63% of Americans say they are extremely or very confident that routine childhood vaccines are effective at preventing serious illness.
Today the South Carolina Department of Health reported 5 new cases in Spartanburg County.
Increased early vaccination began in February, perhaps due to clinician and/or parental concern, the authors say.
Last year the US had 285 measles cases.
