Nearly a dozen measles cases have been reported in Pennsylvania, Virginia and Georgia in recent weeks, according to local health departments. Experts say international travel, coupled with low global vaccination rates, may be behind this wave of cases.
The Philadelphia Department of Public Health has confirmed at least nine cases of measles over the past month after a person contracted the highly contagious virus outside the United States and exposed it to a parent and child at a children’s hospital, according to health department spokesman James Garrow. This exposure then led to a daycare outbreak in Philadelphia involving at least five children.
Virginia health officials are also warning people who recently traveled from two airports in the D.C. area — Dulles International Airport on Jan. 3 and Reagan Washington National Airport on Jan. 4 — of potential exposure to the virus after someone returning to the U.S. from abroad traveled through Northern Virginia.
Additionally, one case of measles has been confirmed in “an unvaccinated resident in the metro Atlanta area,” the Georgia Department of Public Health announced Thursday.
A press release stated, “The individual was exposed to measles while traveling outside the country.” “The Department of Public Health is working to identify anyone who may have been in contact with the individual while they were infected.”
It’s not just the United States. In the UK, the measles outbreak continues to expand: 216 confirmed and 103 probable cases have been reported since October. The UK’s Health Security Agency has declared a national incident to signal the increasing risks to public health.
“It’s always a concern when we have a case of measles because of the potential for it to spread to other individuals,” said Dr. Thomas Murray, a professor of pediatrics at Yale University School of Medicine who focuses on infectious diseases and global health.
“About 90% of people who are exposed will have signs and symptoms of the disease, so it is very contagious.”
Measles was eliminated in the United States in 2002, after the virus had not spread for more than a year, largely due to a “highly effective vaccination campaign,” according to the US Centers for Disease Control and Prevention.
However, clusters can still occur in the United States because the virus has not been eliminated worldwide. There are several countries experiencing active outbreaks.
“Many of the diseases for which we have vaccines have virtually disappeared from the United States, but certainly not elsewhere around the world,” Murray said.
Murray points out that if an unvaccinated person goes to a country where the disease is still common, becomes infected and brings it back to the United States, they could spread the virus to other unvaccinated people.
“There’s a lot of back and forth,” he said. “If there are groups of unvaccinated individuals who cluster closely together and this disease is introduced into that population, you could have large clusters of cases.”
U.S. vaccination rates also remain low, especially among children, according to American Academy of Pediatrics spokeswoman Dr. Christina Jones, a Maryland-based pediatric emergency physician at PM Pediatric Urgent Care.
About 92% of children in the United States have been vaccinated against measles, mumps and rubella (called the MMR vaccine) by age 2, according to a 2023 report from the Centers for Disease Control — falling short of the federal goal of 95%.
The percentage of kindergartners who got state-required measles vaccines also remained below the federal target for the 2022-23 school year, according to CDC data. The rate of vaccine exemptions for children has reached the highest level ever reported in the United States.
Children should get two doses of the MMR vaccine, according to the Centers for Disease Control and Prevention: the first dose at 12 to 15 months of age and the second dose at 4 to 6 years of age.
Before the country’s measles vaccination program, about 3 to 4 million people were infected with the virus each year, and about 400 to 500 people died.
The last major measles outbreak in the United States was in 2018-2019 in Rockland County, New York, and was concentrated among unvaccinated children in Orthodox Jewish communities.
Although the Centers for Disease Control and Prevention reported only 56 measles cases in 2023, Jones says that’s too many for a highly effective vaccine.
She stressed that “most people have never witnessed a case of measles.” “They don’t really have an appreciation for the seriousness of the disease.”
The spread of measles and its symptoms
The measles virus can spread when an infected person coughs or sneezes, and remains in the air for up to two hours after leaving the room, according to Murray. The virus can also live on surfaces such as doorknobs for about the same amount of time.
When symptoms begin, they resemble those of many respiratory illnesses — high fever, cough, red eyes, runny nose and congestion — followed by a “fairly distinctive” rash, Murray said.
“You develop flat red lesions, flat red spots that usually start on your face and move down through the body across the chest, trunk and extremities,” he said. “It can be a whole body rash, and it’s very severe.”
Murray adds that the incubation period for measles is very long. It takes about 10 to 12 days for initial symptoms to appear after exposure.
For this reason, most infected people assume their respiratory symptoms are just a cold until a rash appears three to five days after the initial illness begins, according to Murray. Even then, most people — including some doctors — won’t recognize a measles rash.
“The younger the health care provider is, the less likely they are to see the condition,” Murray said. “But certainly, when it gets circulated, we do everything we can to spread the word about what to look for.”
Low MMR vaccination rates could put unvaccinated and unvaccinated individuals at risk, especially children and those with immune system problems, Jones says.
Measles can lead to serious complications, especially in children under the age of two, such as blindness, encephalitis or inflammation of the brain, and severe pneumonia, according to Murray.
“Measles is also a virus that destroys parts of the immune system,” he said. “There is recent evidence that having measles increases susceptibility to other diseases.”
A rare complication called subacute sclerosing panencephalitis can also occur seven to ten years after infection and may lead to seizures as well as behavioral and mental deterioration.
In addition, a person who does not get the MMR vaccine is at risk for mumps and rubella, which are rare but still common conditions in the United States due to international travel.
In 2023, 436 cases of mumps were reported by 42 jurisdictions, according to data from the Centers for Disease Control and Prevention. Rubella is less common, with fewer than 10 people infected with the virus each year in the United States.
Experts say that if you are fully vaccinated against measles, your likelihood of becoming infected after exposure is very low because the two childhood doses usually confer lifelong immunity.
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“It’s not impossible, but it’s very low,” Murray points out.
But for people who haven’t been vaccinated or have compromised immune systems, the risk increases — “especially if they know they’re in an area where measles is spreading.” “In this case, what you’ll do is you’ll call your health care provider and work with them to determine next steps.”
If you think you may have been exposed to measles, stay home until a plan is in place, Murray advises.
“Call ahead before going to any healthcare facility, because that healthcare facility can anticipate your arrival and ensure you are placed in the appropriate isolation rooms,” Murray said. “The last thing we want to do is have someone with measles sitting in an emergency room waiting room.”
Murray adds that unvaccinated people who know when they have been exposed can get the MMR vaccine within 72 hours of exposure to prevent the disease completely or reduce the severity of the disease.
As for treatment, he says the virus should simply run its course. There is no specific antiviral treatment, and medical care is mainly supportive: stay at home from school or work, rest and drink plenty of fluids.
If a person with measles develops symptoms of encephalitis, such as headache, high temperature, or seizures, he or she should be taken to the hospital immediately.
“Measles hospitalization typically occurs when children experience respiratory distress due to a lung infection such as pneumonia or when they are dehydrated and require intravenous fluids,” Jones said.
Severe cases of measles among children can also be treated with vitamin A, according to the CDC, to support the immune system.
“Vitamin A should be given immediately after diagnosis and repeated the next day,” the agency said.