Measles: Like a Brushfire in a Drought
The beginning of a new year is a moment of reflection on what transpired previously and what changes one would like to implement for the coming months. Many new year’s resolutions focus on trying to live a healthier lifestyle – I have made a few myself. It is perhaps an ironic twist that on January 1stof 2019, the Clark County Public Health Department in the state of Washington began tracking an outbreak of the measles virus in the region. The majority of cases were located in Vancouver, Washington, which is just north of Portland, Oregon. To date, there have been 74 confirmed cases of measles attributed to that outbreak.
Unfortunately, this is not an isolated event.
As I first began writing this article, I realized just how many layers there were to this question. I consulted with two good friends of mine who are epidemiologists, and I came away even more exasperated at the number of problems presented by this virus. Let’s take a step back and first understand the long, arduous history we’ve had with measles virus.
The History of Measles
Although much attention to measles has been within the past 60 years, humans have had to cope with the virus for centuries. Scientific studies have concluded that measles epidemics have occurred in humans since the 11thor 12thcenturies, some asserting as early as the 9thcentury. Measles belongs to a class of viruses termed the “Morbillivirusfamily.” The most closely related contagion to measles is actually Rinderpest virus, which is only one of two eradicated infectious diseases, the other being Smallpox. The idea is that human interaction with livestock resulted in the emergence of measles virus into the human population. Unlike other viruses such as influenza or zika, humans are the only known transmitters of measles.
The sustained transmission of measles amongst humans resulted in millions of deaths in the 18th to 20th century. Epidemics of the highly infectious virus raged throughout corners of the world, including one in the mid 1800s that wiped out 10% of Hawaii. Fiji was also hard hit by measles, resulting in the deaths of ~20,000 natives in 1875. The virus continued to spread at the end of World War II, causing tens of thousands of deaths in localized regions.
In 1963, the first measles vaccine was licensed, which was developed by John Enders and Thomas Peebles. Just a few years later in 1971, the measles vaccine was merged with the mumps and rubella vaccine to give the “MMR vaccine.” Between 1962 and 1982, cases of measles in the United States had dropped by over 90%. Leading up to the turn of the century, measles became an increasingly rare disease in North America. The hope that measles – and its cousin Rinderpest – could be fully eradicated was becoming more a reality.
In the year 2000, the World Health Organization declared the United States had eliminated the measles virus (imported cases still occurred, but continuous indigenous transmission had ceased). This was an accomplishment decades in the making, and it was achieved through coordinated efforts between local, state, and federal health officials. High vaccination coverage rates for the MMR vaccine, rapid identification of local outbreaks, improved healthcare infrastructure and other factors all synchronized to eliminate the transmission of this deadly virus. In medical and healthcare fields, eliminating measles from the United States should rank as one of our crowning achievements of the 21stcentury.
The Present of Measles
So now we arrive to the present day. What exactly happened in the past twenty or so years that changed the downward trajectory of measles towards full disease eradication? We seemingly had the virus “on the ropes” and ready to deal the full knockout blow like we did to Smallpox and Rinderpest. So how is that we are seeing sporadic outbreaks of measles including the ones currently being fought in Washington and New York?
As I’ve mentioned earlier, the measles virus is a highly contagious pathogen. It is transmitted through direct skin contact, inhalation of airborne virus particles, or contact with a contaminated surface. This is serious stuff.It stands alone in ease of transmission, outmatching even highly transmissible diseases such as chickenpox and pertussis,aka whopping cough. In epidemiological terms, the basic reproductive number (often abbreviated R0) of a pathogen is the number of individuals likely to be infected after introduction of the pathogen into a susceptible population.
As you can see, measles virus is truly in a league of its own.
Another important aspect to understand of how we got here is the common misconception of how severe measles can be. Between 1982 and 2012, measles cases were quite rare in the U.S. The states had not had to deal with the consequences of this disease aside from an isolated outbreak here or there. That is not to say that other regions of the world have not had to continuously deal with the virus.
Currently, we are getting a crash course in just how difficult it is to contain this virus and how deadly it can be. An ongoing epidemic of measles in Madagascar has infected over 66,000 people and claimed over 900 lives.
Looking at the ease of transmission and the misconception of the virus’ severity has undoubtedly contributed to its spread in current and previous outbreaks. What was once a potential reality of disease eradication has turned into public health crisis. The complacency by which some dismiss measles is dangerous. Remember: measles is extremely transmissible, and containment efforts during outbreaks can cost tax payers tens of thousands of dollars per infected patient. The ongoing outbreak in Washington has already topped the $1 million mark for containment and treatment. The vast majority of these cases have occurred in patients who either are not vaccinated against measles or do not have immunization records.
Of course, there are other factors at play in the ongoing outbreaks of measles, and I will address them at a later time. I will conclude by restating that measles is unique among all other human pathogens – from virus to bacteria – in its remarkable ease of transmissibility. The virus has been a formidable and deadly force against humans for centuries, and its resurgence around the world speaks to its menace on our health. The virus can inflict a debilitating disease whose impact is vastly underestimated and under-reported.
It is only April, and the United States has already seen more measles cases this year than in 2016 and 2017 combined.
It will likely get worse before it gets better.