10 things to know about measles | Science News for Students

10 things to know about measles

The biggies: It’s highly contagious and can sometimes kill
Feb 6, 2015 — 1:46 pm EST
measles rash

A rash covers the torso of a young measles patient. Once infected, measles patients can transmit the highly contagious virus even before their distinctive rash appears.

teseum/Flickr/(CC BY-NC 2.0)

Many people think that measles, a disease that once hit nearly every child, has disappeared — at least in the United States. It hasn’t. And people who were never vaccinated face the primary risk of getting it. Here’s what you should know.

1. Measles can make people very sick.

It typically causes fever, coughs, runny nose, pinkeye and a distinctive rash. It also can lead to pneumonia (the most common cause of death from this disease) and a swelling of the brain (which can lead to deafness and mental retardation). For every 1,000 children who get measles, 1 or 2 die.

2. Measles is highly infectious.

An infected person can easily pass along the virus to between 12 and 18 others. These typically would be individuals who had never been vaccinated. And a sick person doesn’t even have to be around for someone to pick up the virus. Infectious germs can linger in a room where an infected person coughed or sneezed for up to two hours. Most troubling: People become infectious before their distinctive rash breaks out.

3. Luckily, measles is highly preventable.

Since 1963, a vaccine to prevent it has been widely available. Most people in the United States choose to get the vaccine. (It’s part of a series of two shots that also protects against mumps and rubella. Another version adds protection against chicken pox.)

4. In 2000, U.S. health officials declared measles had been eliminated.

Over the next decade, just a few dozen people per year came down with the disease each year. Most were travelers who picked up the germ while traveling overseas.

Those numbers changed in 2014. That year, 644 U.S. cases were reported to the Centers for Disease Control and Prevention, or CDC. Some people had caught the measles while in another country. Unfortunately, once back in the United States, they remained infectious. And spread the virus. It is likely one (or more) such travelers visited Disney parks that December. They triggered a major 2015 outbreak.

5. In the 10 years before the measles vaccine came into widespread use, nearly all children got measles — at least by the time they were 15 years old.

In the United States alone, back then, an estimated 3 million to 4 million people were sickened each year, the CDC reports. Among these, some 400 to 500 people died and 48,000 were so ill they needed to go to the hospital.

6. If you get measles, you’ll never have to worry about it again.

A single infection will leave someone protected from a repeat infection for the rest of his or her life.

7. Some people can’t get the vaccine.

This includes children under a year old. Their immune systems are not yet mature enough to respond to the vaccine yet and develop protection against the virus. Some illnesses (such as some cancers) — or their treatments — also may suppress the immune system and make it dangerous to get a vaccination.

8. The measles vaccine offers a strong degree of protection. But it isn’t foolproof.

One dose of measles vaccine will protect about 93 in every 100 people who are exposed to the virus, CDC notes. With two doses, that protection goes up to 97 percent. Experts don’t know why a few vaccinated people still pick up the disease. Still, “fully vaccinated people who get measles are much more likely to have a milder illness,” CDC says. “They are also less likely to spread the disease to other people, including people who can’t get vaccinated because they are too young or have weakened immune systems.”

9. Some people worry that a measles vaccination may cause some children to develop autism.

In fact, a 1998 study made that claim. Other scientists looked into the data and found problems with the analysis. Eventually, the scientist who led that first study conceded that his data did not support the claim. As a result, the journal that had published his findings retracted the controversial paper (took it back). The author of the paper also lost his right to practice medicine. What this means: No scientific evidence exists to support a link between autism and vaccinations against measles — or any other disease. And that's even though many scientists have looked hard for such a link.

10. It’s never too late to get vaccinated.

People who don’t know if they were vaccinated (and have no medical records to confirm they got a shot) “should get vaccinated with measles-mumps-rubella (MMR) vaccine,” CDC recommends. A doctor also can test your blood to to see whether you have antibodies to the virus. But CDC points out that “There is no harm in getting another dose of MMR vaccine” — even if no one in your family remembers.

Power Words

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autism (also known as autism spectrum disorders)  A set of developmental disorders that interfere with how certain parts of the brain develop. Affected regions of the brain control how people behave, interact and communicate with others and the world around them. Autism disorders can range from very mild to very severe. And even a fairly mild form can limit an individual’s ability to interact socially or communicate effectively.

Centers for Disease Control and Prevention, or CDC  An agency of the U.S. Department of Health and Human Services, CDC is charged with protecting public health and safety by working to control and prevent disease, injury and disabilities. It does this by investigating disease outbreaks, tracking exposures by Americans to infections and toxic chemicals, and regularly surveying diet and other habits among a representative cross-section of all Americans.

contagion     A disease that can be spread by direct contact with an infected individual or the germs they spread into the air, their clothes or their environment. Such diseases are referred to as contagious.

epidemiologist  Like health detectives, these researchers figure out what causes a particular illness and how to limit its spread.

immune    Able to ward off a particular infection. Alternatively, this term can mean to show no impacts from a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.

immunity  The ability of an organism to resist a particular infection or poison by producing and releasing special protective cells.

infection    A disease that can spread from one organism to another.

measles  A highly contagious disease, typically striking children. Symptoms include a characteristic rash across the body, headaches, runny nose, and coughing. Some people also develop pinkeye, a swelling of the brain (which can cause brain damage) and pneumonia. Both of the latter two complications can lead to death. Fortunately, since the middle 1960s there has been a vaccine to dramatically cut the risk of infection.

outbreak   The sudden emergence of disease in a population of people or animals.

pinkeye  A highly contagious bacterial infection that inflames and reddens the conjunctiva, a membrane that lines the eyelids’ inner surface.

pneumonia  A lung disease in which infection by a virus or bacterium causes inflammation and tissue damage. Sometimes the lungs fill with fluid or mucus. Symptoms include fever, chills, cough and trouble breathing.

transmit  To send or pass along.

vaccine  A biological mixture that resembles a disease-causing agent. It is given to help the body create immunity to a particular disease. The injections used to administer most vaccines are known as vaccinations.

virus  Tiny infectious particles consisting of RNA or DNA surrounded by protein. Viruses can reproduce only by injecting their genetic material into the cells of living creatures. Although scientists frequently refer to viruses as live or dead, in fact no virus is truly alive. It doesn’t eat like animals do, or make its own food the way plants do. It must hijack the cellular machinery of a living cell in order to survive.

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Further Reading

A. Bridges. “U.S. outbreak of measles emerges.” Science News for Students. February 6, 2015.

B. Nelson. “Autism unlocked.” Science News for Students. April 1, 2014.

Centers for Disease Control & Prevention. Frequently asked questions about measles in the U.S.