Worried that your child may have come into contact with the measles virus? Get the facts on what to do before symptoms begin to appear.

Measles virus
Credit: Courtesy of the CDC

Although measles was technically eliminated in the United States in 2000 (meaning it was no longer a constant threat), the disease still strikes hundreds of children and adults every year. In 2014, the virus sickened nearly 650 Americans. The virus causes fever, cold-like symptoms, red, watery eyes, and a rash. At its worse, it can lead to pneumonia, brain inflammation, and even death (affecting 1 to 2 out of every 1,000 kids).

"The measles virus is so contagious that almost every unvaccinated person gets it once exposed," says Sheila Nolan, M.D., chief of pediatric infectious diseases at Maria Fareri Children's Hospital at Westchester Medical Center in Valhalla, New York. You can catch the disease simply by being in the same area with an infected person, even if he doesn't have symptoms. And after that person leaves, you're still not safe: The virus lingers in the air and on surfaces for up to two hours.

Unvaccinated travelers can unknowingly bring the virus to the United States and spread it to those who lack protection. During the first month of 2015 alone, doctors have diagnosed more than 120 people with measles after an outbreak started at Disneyland. So these days, it's becoming more common for day cares and schools to send notices home alerting parents to the measles outbreak. If you believe your child has been exposed to measles somehow, even though no symptoms have appeared yet, here's what you need to know and do.

Check your child's immunization records. Unless you opted out of giving your child the measles, mumps, and rubella vaccine (MMR), she should have received her first dose when she was between 12 and 15 months old and a second dose sometime between ages 4 and 6. A single dose has a 93 percent protection rate against the virus; two doses has 97 percent. Although infants under 6 months are not recommended to get the vaccine, those who are traveling outside the U.S. can get one between 6 and 11 months, with two additional follow-up doses. The vaccine is extremely effective; only about three out of 100 people who get both doses will get sick with the virus. Because there is a slight 3 percent failure risk, you should still keep an eye on exposed vaccinated children and alert your doctor if the first signs of measles, such as fever or cold-like symptoms, appear within a 7 to 21-day timeframe.

Get your unprotected child vaccinated ASAP. "If an exposed child hasn't received her second dose, and it's been at least 28 days since her first MMR vaccine, she should get that second shot now, even if she's not yet scheduled for it," says Dr. Nolan. If your child isn't vaccinated at all and is age 6 months or older, you have 72 hours after exposure to get the vaccine. "After three days, vaccine does not have any effect on the course of the illness," says Richard Rupp, M.D., director of the office of vaccine clinical trials at the Sealy Center for Vaccine Development at the University of Texas Medical Branch in Galveston.

Watch for signs of sickness. If your child starts showing signs of having a cold or the flu, do not take her to the doctor without first talking to someone at the office. If your child has the measles virus, every unvaccinated person who comes into contact with her will be at risk for the disease. This is especially dangerous for infants who are too young to be vaccinated and for pregnant women. Your doctor may ask that you bring in your child after the office is closed so others aren't put at risk, or she may recommend calling ahead to a hospital so they can prepare for your child's arrival.

Ask about immunoglobulin therapy. If you miss that 72-hour window of opportunity to vaccinate your virus-exposed child, your pediatrician may recommend immunoglobulin (IG) therapy. IG is a donor blood product given intramuscularly, or sometimes intravenously, in a hospital setting. "During the treatment, a child receives antibodies from vaccinated donors' blood. This gives the child a sort of passive or secondary immunity," says Dr. Nolan. Doctors typically reserve this therapy for unvaccinated pregnant women, unvaccinated and virus-exposed infants age 12 months and younger, and high-risk children who have compromised immune systems. IG therapy may prevent measles from developing or, at the very least, lessen the symptoms, but a child must receive the treatment within six days of exposure for it to be effective.

Keep your child away from others. The first signs of measles -- fever, cough, and runny nose -- can develop anywhere from 7 to 21 days after exposure. That means virus-exposed, unvaccinated children must be isolated from others -- no school, daycare, church, or other outings -- from 7 days after the first exposure to 21 days after the last exposure. If your child does get sick, she's only contagious for four days after the rash first appears, but definitely contact your pediatrician if you have any concerns.

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