Nearly 500 cases of measles reported across 19 states: CDC
The number of measles cases associated with an outbreak in western Texas has grown to 400, with 73 cases reported over the last three days, according to new data released Friday.
Almost all of the cases are in unvaccinated individuals or in individuals whose vaccination status is unknown, according to the Texas Department of State Health Services (DSHS). At least 41 people have been hospitalized so far.
Children and teenagers between ages 5 and 17 make up the majority of cases at 164, followed by children ages 4 and under comprising 131 cases, according to the data.
It comes as the CDC has so far confirmed 483 measles cases this year in at least 19 states: Alaska, California, Florida, Georgia, Kansas, Kentucky, Maryland, Michigan, Minnesota, New Jersey, New Mexico, New York, Ohio, Pennsylvania, Rhode Island, Tennessee, Texas, Vermont and Washington
This is likely an undercount due to delays in states reporting cases to the federal health agency.
Meanwhile, reports have emerged that some unvaccinated children hospitalized with measles in Texas are showing signs of vitamin A toxicity.
Health and Human Services Secretary Robert F. Kennedy Jr. and other vaccine skeptics have promoted vitamin A amid the measles outbreak. During an interview on Fox News with Sean Hannity earlier this month, Kennedy said that HHS was currently providing vitamin A to measles patients for treatment, claiming vitamin A can "dramatically" reduce measles deaths.
Vitamin A can be used as part of supportive treatment for those who are already sick, with the World Health Organization recommending two doses of vitamin A in children and adults with measles to restore low vitamin A levels, which can help prevent eye damage and blindness.
However, vitamin A does not prevent measles infections, experts previously told ABC News, nor does it directly fight the virus when used as a treatment.
Covenant Children's Hospital, which has treated dozens of measles patients in Texas amid the outbreak, told ABC News in a statement that some parents appear to have given their unvaccinated children vitamin A for "treatment and prevention." Some of those children now show signs of vitamin A toxicity.
Fewer than 10 children have come in with abnormal liver function in routine lab tests, indicating possible vitamin A toxicity, according to Covenant Children's.
Vitamin A toxicity occurs when someone consumes too much vitamin A, and can result in severe complications iincluding liver and kidney damage.
The American Academy of Pediatrics and the Centers for Disease Control and Prevention says vaccination is the most effective way to prevent measles.
The CDC currently recommends that people receive two vaccine doses, the first at ages 12 to 15 months and the second between 4 and 6 years old. One dose is 93% effective, and two doses are 97% effective, the CDC says. Most vaccinated adults don't need a booster.
State health data shows that Gaines County, which is the epicenter of the Texas outbreak, has seen its number of vaccine exemptions grow dramatically in the last dozen years.
In 2013, roughly 7.5% of kindergartners in the county had parents or guardians who filed for an exemption for at least one vaccine. Ten years later, that number rose to more than 17.5% -- one of the highest in all of Texas, according to state health data.
Among the nationally confirmed cases by the CDC, about 97%, are in people who are unvaccinated or whose vaccination status is unknown, the agency said.
Of those cases, 1% are among those who received just one dose of the MMR inoculation and 2% are among those who received the required two doses, according to the CDC.
ABC News' Will McDuffie contributed to this report.
