The number of Americans diagnosed with measles has now reached 839, spanning 23 states.
According to the CDC, there were 75 more cases since last week.
With every new case, health officials have to put in thousands of hours to contain the outbreak.
Although the 10 Los Angeles County cases reported so far are low compared to other areas, state Sen. Dr. Richard Pan says due to the many international travelers, Los Angeles and surrounding cities remain vulnerable.
"We need to make sure we keep the public safe," Pan said.
When a case of measles is even suspected, officials with the L.A. County Department of Public Health start hitting the ground. Every minute counts. Every person exposed can potentially expose hundreds of others.
MORE: How can you tell if you're protected against the measles?
Dr. Sharon Balter is the director of acute communicable disease control at the Los Angeles County Department of Public Health.
"We immediately start working with the patient and the patient's family to figure out every place they've been," she said.
Pan, who is also a practicing pediatrician, explains how thorough officials are when it comes to the investigation.
"They have to check immunization records and especially adults; those can be a little hard to find. And they perform blood tests to test for immunity," he said.
"Sometimes you may have to interview people more than once," added Balter.
Measles outbreak in Southern California: Everything you need to know
"The cost of an outbreak includes staff salaries, a lot of overtime, medications, transportation, laboratory tests, as well as other things," said Dr. Jan King, a regional medical director for the L.A. County Department of Public Health.
To investigate the initial cases, officials estimate that L.A. County Health authorities spent more than $80,000. The state of California spent more than $400,000.
It's hard to get a true cost, because estimates are very preliminary since they don't count additional cases including the ones at UCLA and Cal State L.A., which led to quarantines.
Officials say the costs associated with tracking down just a single exposed person can go as high as $2,000.
"So, you can see over time we can quickly run up a bill that gets into several millions of dollars," said King. "This is very costly to taxpayers."
Add to that, patients themselves may incur costs from lost wages and medical treatment.
Federal health officials say the total cost of treating a single measles case is typically around $32,000.
Measles outbreak proving costly to patients and government agencies
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