Understanding why measles has resurfaced is essential in order to tame it

Understanding why measles has resurfaced is essential in order to tame it
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In recent days, headlines across the globe have carried the news of a record numbers of measles cases occurring all over Europe. Half a century after the measles vaccine was developed, these stories seem to be from a different era. Sadly, they are not.

Understanding why this virus has resurfaced to such an alarming degree is essential to our effort to tame it.

Measles is extremely contagious

Measles is unique among infectious diseases because it is exquisitely contagious. Just one infectious person is able to infect over a dozen others. It is spread through the respiratory route — which includes the respiratory droplets in coughs and sneezes as well as tiny airborne particles that remain suspended in the air for hours.

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Agents that spread this way are not easily amenable to the standard public health measures used to stop other infections, which are transmitted by other means. This extreme contagiousness is why immunization rates in the population need to be above 95 percent to keep the virus at bay. When this threshold of herd immunity is not met, the virus will inexorably find victims whose parents have failed to vaccinate, victims too young to be vaccinated, or victims with medical conditions that preclude vaccination.

The chief symptoms of measles include fever, cough, runny nose, red eyes, and the characteristic rash. While these symptoms might not sound like much, they can be quite severe. For example, in the 2014 Disneyland measles outbreak 1 in 5 children required hospitalization. In about one case per thousand, pneumonia, brain infection, and sometimes death can occur. In fact, nearly 90,000 people died from measles in 2016. There are no specific medications to treat measles and supportive care to reduce fever and maintain hydration are the mainstays of treatment.

The vaccine changed the equation

Prior to the development of the measles vaccine in the 1960s, infection was a treacherous rite of passage and ubiquitous enough that those born before the introduction of the vaccine all show evidence of past infection. The vaccine, currently given in two doses as the MMR or MMRV (measles, mumps, rubella, varicella) around one year of age, is highly effective and is responsible for the elimination of measles in the Americas. For an area to have eliminated measles, all cases that occur in the area have their ultimate origin in another part of the globe. That elimination status is now over as the totalitarian state of Venezuela has had sustained transmission of the same strains of measles for over a year.

Though the vaccine is extremely safe, a thoroughly debunked European-origin myth associating this life-saving vaccine to autism caused a significant proportion of the population to lose confidence in the vaccine creating pockets of unvaccinated individuals all over the world.

Measles as a European import

The surge of measles cases in Europe this year has multiple causes, some of which are country- specific. For example, Ukraine is plagued by infrastructure problems caused by military conflict while Italy has a strong anti-vaccine movement. Irrespective of the cause, the number of cases in Europe should cause alarm in the United States because the sheer amount of travel between European countries and the U.S. guarantees more measles importations and cases. You can expect the 100 or so cases that we have recorded so far this year will go up so long as Europe’s measles cases provide fresh sources of infection. Each of these importations and the subsequent cases that result trigger expensive investigations to identify those who may have come into contact with the virus.

Fortifying against measles with high vaccination rate

The best defense the U.S. can have against the onslaught of cases of measles originating from other parts of the world is to develop the most impenetrable coat of immunologic armor possible. This means ensuring that our population is as highly vaccinated against measles as possible.

While national rates of measles vaccination of kindergartners are around 95 percent, there are geographic locations in which the number falls far below the needed threshold creating a tinderbox of vulnerable children for measles to prey upon. Lax school entry requirements in most states which permit nebulous philosophical and/or religious exemptions to vaccination foster these immunization holes as do inexplicably long “grace periods” for vaccine catch-up. Unless schools end these irrational policies, we will always remain vulnerable.

Dr. Amesh Adalja is a senior scholar at the Johns Hopkins Center for Health Security. Follow him on Twitter @AmeshAA.