In medicine you are taught to be on the look out for “zebras in the horse pasture.”  In other words, you should always keep in mind that an uncommon diagnosis could be sitting right in front of you.  My typical day during the winter months often involves at least a few kiddos coming to see me for fever, runny nose, and a cough.  While my first thought is that what I’m seeing is probably a common virus like the cold or the flu, it’s always in the back of my mind that there could be a zebra lurking out there that is trying to lose its stripe and become just like one of the other horses in the pasture. Unfortunately, right now, that zebra is the measles virus.

“Measles, which is a virus, is one of the most contagious diseases known to man.”

You have likely heard about the current outbreak of measles that began in Disneyland and has now spread to 6 additional states and Mexico.  The most current numbers indicate a total of 68 cases of measles so far this year in the US with the majority of these being traced back to the Disneyland outbreak.  I use the term “so far” because this number is almost surely going to rise.  Measles, which is a virus, is one of the most contagious diseases known to man. The virus is easily spread through coughing or sneezing, and the virus is able to “hang around” in the environment for about 2 hours.  It is estimated that a person with measles will infect up to 90% of those around them who are unvaccinated.  While measles generally causes symptoms such as fever, cough, runny nose, red eyes, and a rash, there are serious complications that can occur.  Studies indicate that 1 out of 10 children will get an ear infection following measles infection, 1 out of 20 will suffer with pneumonia, 1 out of 1000 will get encephalitis or swelling of the brain, and 1-2 out of 1000 will die from measles.

“Through a highly successful vaccine campaign, measles was considered eliminated from the US in 2000.”

So why then, you might ask, have many people never given a second thought to measles until the past few weeks?  Simply put, it’s because the disease was considered eliminated in this country in 2000.  Prior to the introduction of the measles vaccine in 1963, there were between 3-4 million cases of measles each year in this country.  Yes…that’s 3-4 MILLION cases resulting in  400-500 deaths in the US each year!  Through a highly successful vaccine campaign, measles was considered eliminated from the US in 2000.  This means that there were no native cases of measles that started here in the US.  Since 2000, there have been several outbreaks of measles usually in areas that have low vaccination rates, but these cases have been attributed to people coming to the US from foreign countries with the virus in their systems and then passing it along to those who are unvaccinated.

However, last year there was a very concerning rise in the number of measles cases reported in the US.  If you were questioning the resurgence of measles in this country, take a look at this graph.

So why are we seeing this return of a previously eliminated disease? There are a few factors:

Refusal to vaccinate - A British physician named Andrew Wakefield published a study in the Lancet journal in 1998 falsely declaring that there was a link between the measles, mumps, rubella (MMR) vaccine and autism.  The study included falsified data, invasive and unnecessary tests on children, and ethical violations including paying lawyers and patients.  Because of these grievous misgivings, the Lancet retracted the study in January 2010, and Andrew Wakefield was stripped of his medical license (click here to learn about the Lancet retraction).  Exhaustive scientific studies have been done since Mr. Wakefield published his “findings” looking to see if there is any link, what-so-ever, with the MMR vaccine and autism, and all of these studies have shown no connection. But the damage has been done.  A study published last week in Pediatrics found the underimmunization rate in geographic pockets of California ranged from 18-23% of children under 36 months of age (click here to see the full study).  The MMR vaccine is given between 12-15 months of age with a second dose between 4-6 years of age.  The vaccine is highly effective, protecting greater than 95% of people after just one dose.  Of those involved in the current measles outbreak whose vaccination status is known, greater than 80% of them were unvaccinated.  Some of these unvaccinated children were not by parental choice, but because they are too young to have received the vaccine or had underlying medical conditions which prevented them from receiving the vaccine.  The measles vaccine is an example of why “herd immunity”, which means protecting those who can’t be vaccinated by immunizing all of those around them, is so incredibly important - especially in pediatrics.  (Because I feel it is so important to understand “herd immunity,” I will cover more on the topic in a dedicated post in the near future).

Interconnected world - Measles is by no means eliminated in other areas of the world, and it is not just third world countries that continue to battle with this disease.  Many countries in Europe, including the United Kingdom and France, have been struggling with epidemics of measles over the past decade.  According to the World Health Organization, the Philippines had over 50,000 suspected cases of measles last year with 110 deaths.  Of our cases in the US in 2014, 25 of them were confirmed in unvaccinated people who had traveled to the Philippines, and many of the other cases were documented in unvaccinated people with recent travel abroad.

I think there is a degree of complacency that can set in  after the elimination of disease.  People may think, “Oh, I have never seen measles or heard of anyone who has had that illness.  It can’t be that bad.”  Unfortunately, this is the price we all pay when scientific research leads to a highly effective vaccine that eliminates something like measles, and then society, over time, simply forgets the effects of the disease and the great effort it took to eliminate it.

What, then, will it take for people to realize how devastating a virus like measles can be?  Will it be 1,000 cases documented?  Children who are too young to receive the vaccine to start dying from the virus due to the destruction of the “herd immunity” that consistent vaccination creates?  I, for one, as a pediatrician and a mother with a child who can’t yet be vaccinated since he is not 1 year of age, hope that this recent outbreak reminds people of the importance of vaccination with two doses of the MMR vaccine.  To put it another way, let’s make sure that this zebra keeps it stripes.