Measles was considered eliminated from the United States as of 2000. But the disease is still circulating in other parts of the world, so it has been showing up in the U.S. as it's introduced by foreign visitors or unvaccinated American travelers who contract it abroad.
In 2008, 2011, 2013 and 2014, there were more reported measles cases compared with previous years, according to the Centers for Disease Control and Prevention. There have been more measles cases than usual in some countries, such as those in Europe, where Americans travel more often, and measles has appeared in U.S. communities with pockets of unvaccinated people, the CDC says.
Because measles was all but eradicated domestically until recent years, many of you may have basic questions about the disease, its progress and how it is spread. Here are some answers.
What exactly is measles?
Measles is a highly contagious respiratory disease that's caused by a virus.
What are the symptoms?
Measles starts with fever, runny nose, cough, red eyes and sore throat.
Two or three days after symptoms begin, tiny white spots (Koplik spots) may appear inside the mouth.
Three to five days after symptoms begin, a rash breaks out. It usually begins as flat red spots that appear on the face at the hairline; they then spread to the neck, trunk, arms, legs and feet.
Small raised bumps may also appear on top of the flat red spots. The spots may connect 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.
Typically, the fever subsides and the rash fades after a few days.
About three out of 10 people who get measles will develop one or more complications, including pneumonia, ear infections or diarrhea.
Measles may cause pregnant woman to give birth prematurely or have a baby with a low birth weight.
About one child out of every 1,000 who gets measles will develop encephalitis (swelling of the brain), which can lead to convulsions and leave the child deaf or mentally disabled.
For every 1,000 children who get measles, one or two will die from it.
How is it spread?
It spreads through the air, through coughing and sneezing. The virus is so contagious that it can live for up to two hours on a surface or in an airspace where an infected person coughed or sneezed. If one person has it, 90 percent of the people close to that person who are not immune will also become infected.
Infected people are usually contagious from four days before their rash starts, to four days afterward.
How is it treated?
There is no specific antiviral therapy for measles. Any medical care will be supportive and geared toward relieving symptoms, while addressing any complications, such as bacterial infections. An infected person should be isolated for four days after developing the rash.
How effective is the MMR vaccine, which prevents against measles, mumps and rubella?
The vaccine is "extraordinarily effective," says Dr. Jane Seward of the Centers for Disease Control and Prevention's Division of Viral Diseases. "Of the vaccines we have, measles is one of the best."
Still, she says, no vaccine is 100 percent effective.
The CDC recommends that children receive the first dose at 12 to 15 months of age. A child can get the second dose four weeks after that, although it's usually given before the youngster starts kindergarten, at an age somewhere between 4 and 6.
The vaccine is considered to be around 99 percent effective in people who have received the two doses. So if 100 fully vaccinated people were exposed to measles, perhaps one would get sick. The vaccine is about 95 percent effective for people who have only received one dose, so if 100 partly vaccinated people were exposed to measles, perhaps five would contract it.
Why isn't the vaccine 100 percent effective?
There are several reasons for this. Since we're not naturally exposed to the disease anymore, some people's immunity wanes over time, says Dr. George Rutherford, head of the Department of Epidemiology and Biostatistics at the UCSF School of Medicine.
The CDC's Seward notes that for a small group of people, "something in their genetic makeup doesn't let them respond well to the vaccine."
Also, if someone comes in very close contact with measles, it's rare, but possible, for the disease to overcome that person's level of immunity. Even in that case, the vaccine should still provide some protection and prevent the serious side effects of measles that can lead to brain damage and death, says Dr. Susan Huang, medical director for epidemiology and infection prevention at UC Irvine.
I came into contact with someone with measles. What should I do?
If you're vaccinated, you should be OK. Generally, adults born before 1957 grew up at a time when measles was very common and are considered immune, says Dr. Susan Huang, medical director for epidemiology and infection prevention at UC Irvine.
If you can't show proof of immunity, you should get post-exposure prophylaxis. This could be the MMR vaccine, if administered within 72 hours of the initial measles exposure. Babies too young to be vaccinated, unvaccinated pregnant women and immune-compromised people can get protection through immunoglobulin, if administered within six days of exposure.
Be sure to alert your doctor before coming in: Measles is highly contagious, and you could expose other people in the waiting room.
I've only had one dose of the measles vaccine. What should I do?
We consulted different experts on this question, and got different answers.
The California Department of Public Health recommends getting the second shot, while the CDC does not. Greg Wallace, who heads the CDC’s domestic measles, mumps, rubella and polio program, says he is far more concerned about those who are unvaccinated, since it is through that population that the disease is primarily spread.
You can read much more about this question here.
(Source: L.A. County Department of Public Health | Map: Daniella Segura/KPCC)
- Red markers: Clinics that provide free or low cost immunizations to children 18 years of age and younger.
- Blue markers: Clinics that possibly have immunization for adults as well as children.
Call ahead to ensure the clinic offers measles vaccinations and vaccinations for adults.
Do you have questions we haven't answered? Post them in the comments and we'll try to get you an answer.