9 Charts That Will Help You Understand The Current Measles Outbreak

There are currently over 100 reported cases of measles in the U.S. This chart roundup will give you a closer look at what that really means.

Maybe you've heard there's a measles outbreak currently happening in the United States.

The highly contagious virus was initially reported in at least 40 people who were at Disneyland in mid-December, reports the California Department of Public Health.

Since then, the virus has been spreading across the country, bringing the total number of cases to over 120. Here, we've rounded up nine charts that will help you better understand the current outbreak — including why it's happening, where it's happening, and more.

1. This map shows the states currently affected by the measles outbreak.

BuzzFeed News / Via buzzfeed.com

Note: The map was created yesterday (February 4), but is already out of date, due to the news of five additional measles cases reported in a Chicago daycare center today.

2. Here, we can see the number of measles cases reported each year since 2001.

CDC / Via cdc.gov

In 2000, measles was actually declared "eliminated" in the U.S., which means the absence of continuous disease transmission for a full year, according to the CDC. This doesn't mean that no measles cases were reported, but the disease was no longer constantly present in the U.S.

Unfortunately, measles cases appear to be increasing again in recent years, which is likely due in part to the growing number of people who are choosing not to vaccinate their children.

3. This GIF shows how the growing number of unvaccinated individuals can affect how easily measles can be spread throughout a community.

Alice Mongkongllite for BuzzFeed / Via buzzfeed.com

When too many people choose not to vaccinate, it can damage the herd immunity, which refers to the protective effect that occurs when enough people in a community are vaccinated against a disease. This means that even the handful of people who are not vaccinated are protected since the diseases are well contained.

If too many people in a given community are not vaccinated, the herd immunity will disappear, and the virus will spread more freely.

4. These maps from WashingtonPost.com show the amount of public school kindergarteners who entered school with non-medical exemptions to the vaccination requirements in California.

WashingtonPost.com / Via washingtonpost.com

One reason we're seeing more measles cases in the U.S. is because there are pockets of communities around the country where there are unusually high numbers of unvaccinated individuals.

As you can see in this chart, in 2013 there were many more communities where at least 5% of the children entering public kindergartens were unvaccinated than there were in 2000. In order for a community to achieve herd immunity against measles, over 90 to 95% of a population needs to be vaccinated against it. When rates of vaccination exemptions go over 5%, the risk of outbreak goes up.

5. This map from the Immunization Action Coalition shows the types of exemptions allowed across the country.

Immunization Action Coalition / Via immunize.org

California is far from the only state that allows non-medial exemptions to vaccination requirements. In fact, Mississippi and West Virginia are the only two states that do not offer non-medical exemptions.

6. This GIF shows just how contagious the virus really is.

Alice Mongkongllite for BuzzFeed / Via buzzfeed.com

Measles spreads through the air, and is one of the most contagious and easily transmitted diseases there is. When one person gets measles, it can be expected that they will pass it on to 12 to 15 other unprotected people. And each of those 12 to 15 unprotected people can pass it along to 12 to 15 more. And so on.

7. And this chart compares the spread of measles to that of other contagious diseases.

Tom Phillips/BuzzFeed/kanate/Thinkstock / Via buzzfeed.com

Measles is more contagious than SARS, HIV, and Ebola, to put it in perspective.

8. Here's a look at how the symptoms of measles progress after a person is infected.

Jenny Chang / BuzzFeed

It can take about one to two weeks for symptoms to occur. The first indication is a runny nose, high fever, cough, and red/watery eyes. A few days later, mouth sores called Koplik spots can appear. Then comes the red rash, which begins at the hairline and spreads throughout the body.

Severe complications can include dehydration from diarrhea, ear infections (potentially leading to deafness), pneumonia, seizures, and acute encephalitis (brain swelling). The death rate is low, but it can and does happen.

Here's a closer look at what measles actually looks like.

9. And here's a look at just how impressive that measles vaccine is, when enough people get it:

Jenny Chang / BuzzFeed

In the decade before the vaccination program began, there were an average of 549,000 measles cases and an average of 495 measles deaths reported each year, according to the CDC.

In the decade after measles was declared eliminated, the median number of measles cases reported each year was just 62.

So please, vaccinate your children.

And if you're an adult who is unsure of your vaccination status, check with your doctor to find out if you're up to date on your immunizations.