The Amish countryside in central Ohio looks as it has for a hundred years. There are picturesque pastures with cows and sheep, and big red barns dot the landscape.
But something changed here, when, on an April afternoon, an Amish woman walked to a communal call box. She picked up the phone to call the Knox County Health Department. She told a county worker she and a family next door had the measles.
That call spurred nurse Jacqueline Fletcher into action.
"The very next morning we were out to collect samples, collect nasal swabs and also draw blood. And it was just textbook measles," says Fletcher.
A nurse in Knox County for nearly three decades, Fletcher had never seen the illness, but she knew the symptoms.
"The rash. They had the conjunctivitis in the eyes, their eyes were red," she says. "They don't want the light, they sit in the darkened room, wear dark glasses. I mean they were just miserable. High temperatures, 103, 104 temps. So this was the measles."
The largest outbreak of measles in recent U.S. history is underway. Ohio has the majority of these cases — 341 confirmed and eight hospitalizations. The virus has spread quickly among the largely unvaccinated Amish communities in the center of the state.
Fletcher collected samples the afternoon she arrived. A county worker drove them immediately to the state health department and quickly confirmed the measles. The next day, Fletcher says she was on a call with the U.S. Centers for Disease Control and Prevention.
"I remember the first conversation we had with the CDC," she says. "The fellow said, 'You have to get ahead of this.' "
Fletcher started organizing door-to-door vaccinations, and set up vaccination clinics at various locations.
On a Wednesday in mid-June, her clinic takes place in a store that usually sells construction supplies. A steady stream of people come throughout the day. After the workday ends, Amish families form a line out the door while buggies continue to roll into a nearby parking lot.
Most of the children are barefoot, not needing to wear shoes until they work out of the home. The girls wear dark-colored, homemade dresses and bonnets. The boys, pressed trousers and button-up shirts. Inside the clinic, most people are calm, but the younger ones are scared.
Ervin Kauffman reassures his six children as they squeeze into a small back office for their second shot for mumps, measles and rubella since the outbreak began. While many Amish are not against vaccines in principle, many, including Kauffman's children, have never had shots.
"I guess there was no scare to us before," Kaufman says. "I guess we were too relaxed."
Kauffman says the outbreak has changed other customs, too. "We're just now starting with weddings," he says. Spring is the Amish wedding season, a time when hundreds come together, often traveling from other states and sometimes Canada. Those weddings were postponed. Church services, typically held in family homes, were also curtailed. "We didn't have church for almost two months because of the measles, so we wouldn't spread them, so we kind of tried to put the clamp on them," he says.
Knox County Health Commissioner Julie Miller came out to visit Fletcher's clinic to lend support to the vaccination effort. She has no idea how many are still at risk of contracting the illness.
"It's hard to answer that because we still don't know what the number is of who has the potential to be sick," she explains.
That's because there's simply no official count of how many Amish live in Ohio. Researchers at Ohio State University estimate that there are about 33,000 Amish living in the six-county area where the outbreak began.
At last count, 8,000 people in those counties had been vaccinated.
But Miller fears the measles will continue to spread because there is still resistance to vaccinations.
Paul Raber, 35, is one of those who are skeptical. He decided to get the measles vaccine for himself and his family. But the father of 11 isn't sure if he or his family will get other shots. "We might, we might," he says, sounding doubtful.
Meanwhile, the virus is spreading, with more cases being reported in nearby Holmes and Stark counties.
This story is part of a reporting partnership between NPR, WCPN and Kaiser Health News.