Public health officials across California have been working intensively to prevent this year's measles outbreak from spreading further. If they succeed, it will be thanks to old fashioned detective work.
Orange County's Health Care Agency has been particularly busy. Since the beginning of the year, Orange County has reported 22 cases of measles, more than one-third of all the cases in the state.
Each of those sick people could have exposed hundreds -- or even thousands -- of others -- at school, work, or in the doctors office. A team of 10 public health nurses and epidemiologists has been tasked with investigating each case, and each potential case.
First, a team member interrogates each person with the measles, says public health nurse Maureene Cruz.
"Where could they have gotten it, where were they in the three weeks prior, the month prior?" Cruz says. "When we start digging, that’s where we can find connections between other cases."
Then, they call everyone who might have been exposed to someone with measles.
You could think of a measles investigation as looking like the whiteboard in a detective movie, where the relationships among the suspects and the victims are mapped out. Dr. Matt Zahn, chief of epidemiology for Orange County, describes those relationships as "rings" of exposure.
"If you have one person who exposes hundreds of people, even one or two of those people getting sick is a problem, because then the ring starts all over again, and the work starts all over again," Zahn says.
Another challenge for Zahn's team: people with measles are contagious up to four days before the telltale rash appears. And experts say that measles can linger in the air for an hour or two after the sick person has left the room.
When Cruz and her team call potential victims, they warn that it could take up to two weeks to develop a fever, and even longer for any red bumps to appear. Cruz estimates she’s called thousands of people since this year's outbreak began.
These investigations are also time sensitive. From the time of exposure, officials have just six days to give someone an antibody known as immunoglobulin, according to Dr. Zahn.
To make matters worse, immunoglobulin costs several hundred dollars per dose, and there is not enough to go around. So Zahn says the county is saving it for those most vulnerable to infection, like unvaccinated newborns, pregnant women, and anyone who’s immune-compromised.
These types of people tend to congregate in doctors offices, says Zahn, adding, "those high-risk people are really the people that we’re emphasizing right now."
This type of detective work is also expensive. Orange County health officials say they don’t know how much they have spent so far investigating this year’s measles outbreak.
In 2008, it cost taxpayers more than $120,000 to investigate and contain a measles outbreak in San Diego County that sickened 12 people, according to state and county statistics.
There has been some good news recently: Orange County has not had any new cases for a couple of weeks. Still, Dr. Zahn says his team of nurses and epidemiologists will keep working until they have tracked down every last lead.