When Paula Hinshaw was a child, no vaccine for measles existed.
In 1951, when she was 6 years old and many of the students in her school came down with measles, so did she.
"Getting measles was part of childhood at that time," Hinshaw said. "There was no vaccine against it."
The highly contagious virus was hard on Hinshaw, who lives in Centertown. It scarred her corneas, causing permanent reductions in her eyesight. It affected her hearing.
Changes were gradual, she said.
"Especially when you're a child, you just think that's the way things are supposed to be," she said.
Her parents were forced to strap Hinshaw to a chair to irrigate her sinuses.
"I remember nearly dying. I woke up crying, and I was in a little cot next to my mother's and father's bed," Hinshaw said. "It just hurts me that parents don't see that they are hurting their children by not having them vaccinated."
Her concern reflects that of an expanding number of people, particularly in the medical profession, who are worried about the growth in people choosing to opt out of having themselves or their children vaccinated for medical, religious or even philosophical reasons.
Some diseases that had nearly been wiped out in the United States, particularly measles, have begun to re-emerge.
In 2000, the Centers for Disease Control and Prevention announced measles had been eradicated in the U.S.
As of April 11, the CDC reported, there had been 555 confirmed measles cases in the U.S. for 2019. That was the most of any of the entire previous 10 years, except in 2014, when there were 667 measles cases for the year.
Measles is a highly contagious virus that thrives in mucus within an infected person's nose and throat, according to the CDC. It can spread to other people through coughing and sneezing and can live for up to two hours in an airspace after an infected person coughs or sneezes.
Others who breathe the contaminated air or touch an infected surface and transfer the virus to their eyes, noses or mouths may become infected. And 90 percent of people who aren't immune who come into contact with an infected person will likely come down with measles, too.
Symptoms of measles generally appear about seven to 14 days after a person is infected. They typically begin with high fever, cough, runny nose and red, watery eyes. Two or three days after symptoms begin, tiny white spots may appear inside the mouth.
Three to five days after symptoms begin, patients will break out with a rash that usually begins as flat red spots at the hairline and spread downward to the neck, trunk, arms, legs and feet. Spots may join together as they spread from the head to the rest of the body. When the rash appears, a person's fever may spike to more than 104 degrees.
Infected people can spread measles to others from four days before through four days after the rash appears, according to the CDC.
The CDC website shows there are currently six measles outbreaks in the U.S. — two in New York and one each in Washington state, New Jersey, California and Michigan.
A measles outbreak is defined as three or more cases.
One case was reported in eastern Missouri this year.
Worldwide, measles cases are up 300 percent over 2018, according to the World Health Organization.
WHO named "vaccine hesitancy" as a major global health threat. The organization said conspiracy theories in the U.S. and Europe have contributed to a decline in the number of people receiving vaccinations.
"Addressing vaccine hesitancy requires an understanding of the magnitude and setting of the problem, diagnosis of the root causes, tailored evidence-based strategies to address the causes and monitoring and evaluation to determine the impact and sustainability of the intervention," the WHO website states.
For years, organizations like the National Vaccine Information Center warned of a connection between the Measles-Mumps-Rubella (MMR) vaccine and a rise in autism. They cited a now-discredited 1998 study linking the two. The doctor who conducted the study later lost his license.
There is no evidence vaccinations increase a child's risk of having autism, health care workers said. A rising vaccine hesitancy concerning MMR vaccine led to a 2002 Danish study, which found no relationship between the vaccine and autism. Authors of the study said there is a vast majority of scientific findings that conclude there is no link.
Additionally, a number of religious groups object to vaccinations because of theological concerns.
Dutch Reformed Congregations have a tradition of declining immunizations because, they said, immunizations interfere with divine providence, according to a report from the Vanderbilt Medical Center.
Faith healing denominations — whose basic tenets include the belief that disease can be cured or prevented by focused prayer — may oppose vaccinations.
While it maintains a large database of vaccination laws in each of the states, the National Vaccine Information Center is a leading anti-vaccine organization and has been criticized for providing misleading information about vaccines.
The organization has advocated for informed consent — in which patients give doctors permission to perform treatments based on knowledge of its possible risks and benefits — specifically for vaccinations.
Critics said the organization doesn't inform people about how uncommon the risks are, nor how beneficial the immunizations can be.
The Los Angeles Times found people often seek knowledge about immunizations online, often finding arguments persuasive, if also misleading. And researchers are too often turning to social media for information, regardless of its accuracy.
In February this year, U.S. Rep. Adam Schiff, D-California, sent a letter to Sundar Pichai, CEO of Google, and Mark Zuckerberg, CEO of Facebook, expressing his concern over their companies' platforms allowing information to surface discouraging parents from vaccinating their children.
"The scientific and medical communities are in overwhelming consensus that vaccines are both effective and safe," he wrote. "There is no evidence to suggest that vaccines cause life-threatening or disabling diseases, and the dissemination of unfounded and debunked theories about the dangers of vaccinations pose a great risk to public health."
Even parents and guardians who seek accurate information run the risk of finding pages and videos that present misinformation, he continued.
Shortly after receiving the letters, the companies announced changes to their platforms. YouTube, which is owned by Google, has stopped anti-vaccine channels and videos on the platform from receiving money from viewers. Facebook has worked to make the advertisements less visible.
Hinshaw said her concern is if people choose not to immunize their children, communities will return to a time when parents had fears about conditions that threatened their children's health.
"It concerns me that a child would have to go through what I went through," she said, "what my brother-in-law went through with polio, what my best friend in grade school — who was confined to a wheelchair because of polio — went through."