A decade ago, the public health community celebrated a major milestone when measles, a disease that once caused thousands of deaths each year in the United States and tens of thousands of hospitalizations, was declared eliminated. But in many parts of the world the disease still rages, posing a growing threat to U.S. travelers and those who come in contact with them.
As of early August, more than 180 cases of measles had been reported to the Centers for Disease Control and Prevention in 2011, which is the highest number of reported cases since 1996 and more than double the number of cases reported in all of 2008, when the disease last spiked. The majority of cases have been brought into the United States by travelers and spread to others who lack immunity to the illness.
“Almost all of these (cases) are coming from importations, and the striking thing is that so many of them are coming from France, where they’ve had thousands of cases of measles in the last month,” said APHA member Samuel Katz, MD, professor of pediatrics at Duke University Medical School and chair of the National Network for Immunization Information. “This year just seems to be a higher year for importations. Part of it may be the fact that people are traveling and people who haven’t been immunized are picking up the virus and bringing it back, and it’s the most highly contagious virus that we deal with.”
A CDC study released in April attributed the unusually large number of importations into the United States this year to recent increases in measles in countries visited by U.S. travelers, particularly countries in Europe. More than 30 countries in Europe, including France, the United Kingdom, Spain and Switzerland, have reported increases in measles, the study said.
France has been the most frequent source of measles importation into the United States this year, said the study. About 10,000 cases have been reported in France during the first four months of 2011 as well as at least a dozen cases of measles-related encephalitis, hundreds of cases of measles- related pneumonia and at least six measles-related deaths.
Besides Europe, Africa and Asia are also among the sources of imported cases to the United States this year, according to CDC. In 2011, Nigeria had nearly 30,000 suspected cases of measles as of late April, with 122 deaths. Meanwhile, the Democratic Republic of Congo had reported heightened measles activity since August 2010. In January and February 2011, more than 16,000 suspected cases and 107 deaths were reported.
Abubaker Kabir, 5, is treated for measles at a hospital in Kano, Nigeria, in 2005 while his mother, Ladi, left, watches. Nigeria is one of the countries in Africa with a high number of measles cases this year. As of April, there were 30,000 suspected cases of the disease and 122 related deaths in the country.
Photo by George Osodi, courtesy AP Images
The increase in measles cases in Europe is also being felt south of the U.S.
In July, Mexican health officials announced that a case of measles had been diagnosed in a child who had flown into Mexico from France. To ward off an outbreak, Mexican health officials contacted 140 passengers who had traveled on the child’s flight, informing them of their possible exposure and the symptoms to watch for. Mexican health officials also mounted an immunization effort that included vaccinating people living in the child’s neighborhood as well as providing measles vaccinations to at-risk residents younger than 39.
A passenger is vaccinated against measles at Benito Juarez International Airport in Mexico City in July. Health authorities began a vaccination campaign after a case of the disease was brought into the country by a child traveling from France.
Photo by Alfredo Estrella, courtesy AFP/Getty Images
“It is transmitted so easily from an infected person to a non-immunized or unprotected person,” Katz told The Nation’s Health. “We have had instances of people on airplanes, where someone has sat two rows away, coughing and incubating measles and someone two rows back gets measles from that transmission.”
Thanks to a highly effective measles vaccine and widespread immunization, the ongoing transmission of endemic measles was declared eliminated in the United States in 2000. But while measles is almost gone from the United States, about 20 million cases still occur each year around the globe. In some parts of the world — particularly in areas of Africa and Asia — measles remains one of the leading causes of death among children. According to the World Health Organization, 164,000 people died from measles in 2008, most of them children younger than 5.
So serious is the increase in cases this year that CDC issued a health advisory on measles in June, warning that the increase in measles cases and outbreaks in the United States underscore the ongoing risk of importations and the need for high measles vaccine coverage.
“Measles makes you sick,” said Paul Offit, MD, chief of the Division of Infectious Diseases and director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “When you see kids with measles, it’s pretty scary, and probably the best example of that is if you look at hospitalization rates.”
According to Offit, between 30 percent and 35 percent of U.S. children who are getting measles are being admitted to hospitals because health care providers are “so surprised” by the disease, Offit said.
“I think people don’t remember measles,” Offit said. “Now that we’ve eliminated the disease for the most part in this country, we’ve eliminated the memory of the disease.”
A respiratory disease caused by a virus, measles causes fever, a runny nose, cough and a rash all over the body and is transmitted by contact with an infected person through coughing and sneezing. According to CDC, it is so contagious that any child who is exposed to it and is not immune will probably get the disease, which can cause severe health complications, including pneumonia, encephalitis and death.
While overall vaccination coverage rates are high in the United States, some parents are failing to vaccinate their children and are opting out because of misconceptions about the safety of vaccines, as well as religious or philosophical reasons.
“Prior to say 2008, every year you would see 60 to 65 people come into the United States with measles, but you wouldn’t see it spread,” Offit told The Nation’s Health. “What’s worrisome about what happened in 2008 and what’s happening now is that you see it spread from one American child to another because you have a critical number of unvaccinated children. In other words, then it was sort of like the ball would get thrown up against the wall and it would just bounce back. Now it sticks a little bit because you have a critical number of unvaccinated people.”
Maintaining high immunization rates with the mumps-measles-rubella, or MMR, vaccine is the cornerstone of outbreak prevention, infectious disease experts say. The vaccine is recommended routinely for all children at age 12 months to 15 months, with a second dose at ages 4 to 6.
Prior to the introduction of the first measles vaccine in 1963, nearly all children got measles before their 15th birthday. The virus caused pain and suffering, including as many as 500 deaths each year and 48,000 hospitalizations. According to the National Network for Immunization Information, the vaccine has led to a 99 percent reduction in the incidence of measles in the United States.
Jane Seward, MBBS, MPH, deputy director of CDC’s Division of Viral Diseases, said health care providers and parents need to be aware of the special recommendation for early measles vaccination for infants ages 6 to 11 months when they travel overseas.
“Usually children wait until 12 (months) to 15 months to get their first measles dose,” Seward told The Nation’s Health. “There is a regular recommendation for vaccination of children 6 (months) to 11 months with one dose who travel, and we think there may not be a high level of awareness about that recommendation, or that people don’t think of Europe as a place where they might get measles. So we want to highlight that.”
Measles is extremely contagious, Seward said, and while no deaths have been reported in the United States this year, “you never know,” she said.
“There is always the risk of death,” Seward said. “You could get a death in 100 cases. It’s just a matter of chance.”
The measles virus has the greatest potential for spread when it “drops into a pocket of unvaccinated people,” she said. And unlike cold or flu viruses, which can be combated with frequent handwashing, the measles virus is “aerosol,” Seward said, meaning that it goes up into the air and travels through rooms and air conditioning.
“It can get into tiny, tiny particles that are much smaller than large droplets,” she said. “Aerosol goes up into the air when you cough and travels into the air conditioning and all around the room. It’s spread by the respiratory route, not by hands so much.”
Seward said parents need to understand that the vaccine will not only protect their own child “but it also protects others in your community who are too young to be vaccinated or too sick to be vaccinated, or who are ineligible for the vaccine, for example, because they might have leukemia. And those children can only be protected through high immunity around them from everybody who can make the choice to be vaccinated.”
For more information on measles, visit www.cdc.gov/measles.
- Copyright The Nation’s Health, American Public Health Association
