Even the one case of measles confirmed in East Tennessee last week has triggered a costly emergency response. The state's Department of Health treats every patient like a ticking time bomb.
It usually starts with a call from a local doctor treating someone who just traveled abroad and becomes very ill, then develops the signature rash.
"It's like a stopwatch starts from the minute you pick up the phone," says Kelly Moore, who oversaw the response to every measles case in Tennessee between 2004 and 2018. She now teaches at Vanderbilt University and serves on the immunization panel for the Centers for Disease Control and Prevention.
Officials act quickly because there's a 3-day window after exposure when a vaccine still might help someone who hasn't been inoculated. So experts drop whatever they're working on to interview the patient and figure out everywhere they've been and everyone they've seen.
Then they track down anyone who was in the same room with the patient since developing symptoms. And that could be a lot of people if they were on a plane or went to a clinic, a doctor's office, a hospital — or all three.
"Perhaps they went to a pediatric clinic and exposed a lot of infants who are too young to be vaccinated. Then the scale of the response can be enormous and easily exceed $100,000," Moore says.
"The thing that's hard to imagine now for the public is: Why does it cost so much to have so few cases, compared to all the cases we used to have when it wasn't such a big deal?"
The U.S. had millions of measles cases each year and hundreds of Americans died annually up until a vaccine was developed. But by 2000, measles was considered completely wiped out in the U.S.
The current national outbreak has been blamed on concentrated communities of low vaccination rates.
Current Tennessee officials won't put a hard dollar figure on what the response to each measles case costs taxpayers, though they acknowledge it's a lot.
Tennessee's epidemiologist, Tim Jones, says "pulling out all the stops" — which even involves driving out to someone's house if they don't answer the phone — could save money if it halts the highly contagious disease from spreading.
"Finding close contacts can be a lot of work," Jones says. "And that's one of the reasons we try to catch these very, very early before the list gets too big."
The largest Tennessee outbreak in recent years was in Memphis. In 2016, seven cases surfaced, exposing nearly a thousand people to a virus so contagious that it can linger in a room for two hours after a contagious person has left.
If confirmed infections reach into the hundreds, like they have in New York this year, Jones says the strategy would have to change. But for now, Tennessee health officials are treating measles like even one case is too many.
"Early on, when we can do this tracking on an individual basis, that's certainly preferable," Jones says. "Because we want those individuals to take it very seriously and we don't want to unnecessarily panic the public."