Measles cases are rare in the U.S., with 175 occurring so far this year. Those statistics include 20 hospitalizations and no deaths.

Compare that to the years before the measles vaccine and it looks like we've made major progress. The U.S. typically had 400 to 500 deaths from measles per year before 1963 and virtually every child became infected, vaccine experts and officials with the U.S. Centers for Disease Control told reporters today, which is the 50th anniversary of the approval of the measles vaccine.

But officials are concerned about a spike in cases, CDC director Dr. Tom Frieden told reporters.

Here's the reason: This year's case total is up 192 percent over the typical 60 cases per year reported in the U.S. Virtually all the cases were imported  from foreign travel, many of them from Western Europe where clusters of parents are hesitant about vaccinating their children.

And the domestic outbreaks are occurring in similar pockets of unvaccinated children, officials said.

On an average day, 430 children – 18 every hour – die of measles worldwide. In 2011, there were an estimated 158,000 measles deaths.

With an increase in global travel and a surge of activity expected with next year's Sochi Olympics and the World Cup in Brazil, CDC officials say measles is a plane ride away and travelers need to be extra vigilant about ensuring they are vaccinated.

Measles, like smallpox, can be eliminated. But it's so contagious that the vast majority of a population must be vaccinated to prevent sustained outbreaks, officials said. They also noted that people born before 1957 have a natural immunity to measles.

A story in today's Arizona Daily Star talks about local outbreaks of whooping cough, also known as pertussis. The story is sparking passionate local discussion about vaccines and no doubt the doctor featured in the story is taking some heat for his hard line pro-vaccine stance.

Though vaccination rates remain high in Arizona, there has been a trend of parents seeking vaccine exemptions for their children based on personal beliefs. The number of such exemptions in kindergarten children doubled between 2000 and 2010, state officials say.

Clusters of non-medical vaccine exemptions are occurring nationwide and epidemiologists say it's a result of inaccurate information that's circulating among parents.

Diseases like measles have become victims of their own success - hardly anyone sees them anymore, and that has made people complacent and in some cases fearful of the vaccines rather than the diseases themselves.

An article published in the journal Pediatrics today says American doctors should suspect measles in children with high fever and rash, "especially when associated with international travel or international visitors."

"A measles outbreak anywhere is a risk everywhere," Frieden said.

“The steady arrival of measles in the United States is a constant reminder that deadly diseases are testing our health security every day. Someday, it won’t be only measles at the international arrival gate; so, detecting diseases before they arrive is a wise investment in U.S. health security."