Rates of measles are usually fairly low in the United States. Since 1997, measles cases had ranged from a low of 37 in 2004 to a high of 140 in 2008.
Before the routine measles vaccination though, rates of measles cases were high. There used to be about 500,000 cases of measles and high rates of complications from those cases, including about 500 measles deaths each year in the United States.
After the last big measles outbreak in 1989 and the introduction of the MMR booster dose in 1994, cases of measles have dropped. In 2000, it was even declared that the endemic spread of measles in the United States had ended, and continued cases were all imported from outside the U.S.
Measles Outbreaks
Unfortunately, imported measles cases can still trigger small measles outbreaks in people who are at risk for measles, include those who are unvaccinated or under-vaccinated. This includes:
- infants who are too young to get their first dose of MMR
- toddlers and preschoolers who are too young to get their booster dose of MMR
- children who have a problem with their immune system, and so either can't get the MMR vaccine, or had the MMR vaccines but they don't work effectively because they are immunocompromised, such as children who are receiving chemotherapy for cancer
Most cases of measles are in children and adults who have simply not been vaccinated by choice though.
In 2011, there were more cases than any other year since 1996 (508 cases). We had at least 223 cases in 2011, passing the recent record set in 2008 (140 cases).
International Measles Outbreaks
In addition to many developing countries where measles is still endemic, measles outbreaks have been reported internationally in:
- Quebec, Canada - 760 cases (most since mid-1990s)
- France - over 15,000 cases in 2011
- Spain - 1,986 cases in 2011
- Romania - 4,015 cases in 2011, including 582 cases of pneumonia and 3 cases of encephalitis and 1 death
- Italy - over 5,181 cases in 2011, including outbreaks with 1,500 cases in Bolzano, Italy which is "known to have the lowest measles vaccination uptake" in Italy and strong "vaccination opposition" and the Lazio region (over 1,000 cases)
- Germany - 1,609 cases and 1 death in 2011
- UK - 1,083 casesin 2011 (up from 374 in 2010)
- Ukraine - 4,500 cases so far in 2012
- Russia - at least 1,000 cases, with cases in 47 regions of Russia in 2012
- New Zealand - just over 600 cases (most in Auckland)
- Switzerland - 651 cases in 2011
- Belgium - 555 cases in 2011
- Ireland - at least 278 cases in 2011
- Bulgaria - 24,000 cases and 24 deaths in 2010
- Southern Africa, including measles outbreaks in Lesotho, Malawi, Namibia, Mozambique, South Africa, Zambia, and Zimbabwe
- Eastern Africa, including measles outbreaks in Ethiopia and Kenya
High numbers of measles cases in Europe which began in 2010 continued in 2011, with more than 30,000 cases in each of those years. Overall, there were more than 30,000 cases of measles in Europe so far last year, 8 deaths, 27 cases of measles encephalitis, and 1,482 cases of pneumonia, with most cases in unvaccinated (82%) or incompletely vaccinated (13%) people.
France was the hardest hit, with over 15,000 cases of measles and at least 6 deaths last year, 651 cases of severe pneumonia and 16 cases of encephalitis.
So far in 2012, 14 countries in Europe are reporting measles cases, indicating the start of a new measles season. It looks like there may be fewer cases so far this year though, so maybe this years's measles season in Europe might not be as big as last years.
SSPE in Europe
A new development is the report in Germany of two cases of subacute sclerosing panencephalitis (SSPE), a rare, late complication of measles. On average, subacute sclerosing panencephalitis occurs about seven years after having a natural measles infection. The CDC reports that it causes a "progressive deterioration of behavior and intellect, followed by ataxia (awkwardness), myoclonic seizures, and eventually death."
One of the cases is in a six-year-old girl who had developed measles when she was seven-months-old and too young to get an MMR vaccine. Although she was only just diagnosed in October, she is already unable to walk and talk and has to be fed via a gastric tube.
The other case is in a 13-year-old girl who died in October. It is thought that she developed measles as an infant after being exposed to an unvaccinated 11-year-old boy at her doctor's office.
Although there is no cure for SSPE, it is important to keep in mind that like measles, it can be prevented with the MMR vaccine.
2008 Measles Outbreaks
Of the 140 measles cases in 2008 in the U.S., 17 were linked to travel from Italy, Switzerland, Belgium, India, Israel, China, Germany, Pakistan, the Philippines, and Russia.
Of the 17 initial travelers who brought measles into the U.S. with them, 9 were US residents and 8 were visitors. This lead to measles cases in Illinois (32 cases), New York (27), Washington (19), Arizona (14), California (14), Wisconsin (seven), Hawaii (five), Michigan (four), Arkansas (two), and Washington DC, Georgia, Louisiana, Missouri, New Mexico, Pennsylvania, and Virginia (one each).
It is also important to note that:
- Only six of the patients (5%) had received two doses of MMR.
- Sixteen of the measles cases (13%) were in children who were too young to be vaccinated.
- One hundred and twelve of the cases (91%) were unvaccinated or had an unknown vaccination status.
- Sixty-three of the cases (66%) were in people who had a nonmedical vaccine exemption for vaccination.
And most importantly, according to the CDC, "the measles outbreaks in 2008 illustrate the risk created by importation of disease into clusters of persons with low vaccination rates, both for the unvaccinated and those who come into contact with them."
Anatomy of a Measles Outbreak
A closer look at the California measles cases during the 2008 measles outbreak can help parents understand even better what happens during one of these outbreaks.
A child who is unvaccinated because his parents have a personal belief vaccine exemption travels to Switzerland with his family. A week after returning home from the trip, he gets sick, but returns to school after a few days. He then develops a rash and sees his family physician, followed by his pediatrician, and then makes a trip to the emergency room because he continues to have a high fever and rash (classic measles symptoms).
He is eventually diagnosed with measles, but not before eleven other children are infected with measles, too. This includes two of his siblings, five children in his school, and four children who were exposed at his pediatrician's office.
It is not as simple as that, though. During this measles outbreak:
- Three children who became infected were younger than 12 months of age, and therefore too young to have been vaccinated
- Eight of the nine children who were at least 12 months old were unvaccinated because they had personal belief vaccine exemptions
- About 70 children were placed under voluntary quarantine for 21 days after their last exposure because they were exposed to one of the measles cases and either didn't want to be vaccinated or were too young
- One of the infants with measles traveled to Hawaii, raising fears that the measles outbreak could spread there too
All together, 839 people were exposed to the measles virus.
At least one of them was a 10-month-old infant who got infected at his well child checkup, was too young to have gotten the MMR vaccine yet, and ended up spending three days in the hospital - time his parents spent "fearing we might lose our baby boy."
The parents of this 10-month-old weren't looking for a vaccine exemption and didn't want their child to catch measles, a life-threatening, vaccine-preventable infection. Instead, they were counting on herd immunity to protect them until their child could be protected with an MMR vaccine. They were one of "those who come into contact with them" that got caught up in a decision of some other parents to not vaccinate their child.
Measles Outbreaks - What You Need To Know
Other things to know about measles and measles outbreaks include:
- From 2 to 5% of people do not respond to their first dose of measles vaccine, which is why a booster dose is recommended.
- More than 99% of people develop immunity to measles after two doses of a measles vaccine, like MMR.
- A booster dose of MMR was first recommended in 1990 (for four year olds), so many adults born before 1986 may not have had two doses of MMR.
- Measles is fatal in about 0.2% of cases.
- The measles virus is spread by respiratory droplets and can stay in an area for up to two hours after a person with measles symptoms has left.
- People with measles are contagious from four days before they develop the measles rash to four days after it goes away.
- Call your pediatrician if you think your child has measles (don't just show up at their office or in the ER), especially if he develops a high fever and/or rash during a local measles outbreak or after a trip out of the country.
Most importantly, parents should understand that a measles vaccine (MMR) is the best way to protect your child from measles, and is especially important if there is a measles outbreak in your area or if you are traveling to an area with high rates of measles.
Sources:
CDC. Measles: Unprotected Story: 106 Degrees: A True Story. November 4, 2010. Accessed February 2011.
CDC. Outbreak of Measles --- San Diego, California, January--February 2008. MMWR. February 29, 2008 / 57(08);203-206
CDC. Update: Measles --- United States, January--July 2008. MMWR. August 22, 2008 / 57(33);893-896
European Centre for Disease Prevention and Control. European Measles Monthly Monitoring, February 2012. Surveillance reports - 21 Feb 2012.
l'Institut de Veille Sanitaire. Measles outbreak in France. Updating of data to 15 November 2011.
Manual for the Surveillance of Vaccine-Preventable Diseases (4th Edition, 2008)
The Pink Book: Epidemiology and Prevention of Vaccine Preventable Diseases. Updated 11th Edition, (May 2009)
World Health Organization. Measles Fact Sheet. December 2009. Accessed February 2011.
