Nine days after returning home from a Mediterranean cruise, a Sardinian woman developed a rash. She visited a hospital emergency department, was diagnosed with measles, and remained hospitalized for three days. While infectious, she transmitted the disease to six people: a co-worker, a relative, three healthcare workers, and a hospital visitor.
Before long, health authorities had linked 136 measles cases to the cruise. Of these, 80 were traced to the Sardinian woman, and 50 had been transmitted in a hospital or by a healthcare worker.
Worldwide, measles is surging — cases have risen 300% in the last year, following two consecutive years of increases — and hospitals are often ground zero for outbreaks.
“Measles is one of the most contagious viral diseases, and patients frequently visit hospitals or health care facilities,” observed Italian researchers who analyzed the Sardinian outbreak.
In hospital waiting rooms, the potential for airborne transmission of measles is high — higher than for other airborne infections, such as tuberculosis and influenza.
“Measles transmission in healthcare settings remains a serious public health concern,” cautions the U.S. Centers for Disease Control and Prevention (CDC).
Measles outbreaks plunge hospitals into chaos, and for patients, the consequences can be severe, including pneumonia, brain damage, blindness, and hearing loss.
“Even in high-income countries, complications result in hospitalization in up to a quarter of cases and can lead to lifelong disability,” reports the World Health Organization (WHO). In the Sardinian outbreak, more than half of the patients suffered complications.
For measles to be contained, community vaccination rates must climb sharply — that’s a given. Yet it’s not enough. In addition, hospitals must bolster infection-control policies and deploy more advanced air-purification technology.
Why Measles Has Surged
Currently, all the world’s regions report “sustained rises” in measles cases, according to WHO, ranging from a 40% year-over-year increase in the Western Pacific to a 300% increase in Europe to a 700% increase in Africa.
In 2017, the most recent year for which global estimates are available, measles caused nearly 110,000 deaths, up 20,000 from the previous year.
Of course, these numbers represent a marked improvement over the pre-vaccine era. Before 1980, when the measles vaccine became widely available, 2.6 million measles patients died each year.
Yet the current numbers are alarming, given that measles is preventable and in numerous countries was declared eliminated in 2000.
Today’s measles crisis stems primarily from a worldwide decline in vaccination rates. For several years, coverage with one dose of measles vaccine has stagnated at 85%, far short of the 95% needed to prevent outbreaks. Second-dose coverage stands at just 67%.
Political instability in South America, vaccine shortages in Africa, fear of vaccines among pockets of American parents, distrust of government among insular communities around the globe — these and other circumstances are driving the crisis.
In addition, outbreaks are fueled by global travel — every American outbreak since 2000 has started with a case imported from overseas — and by the exceedingly contagious nature of the virus.
Just How Contagious is Measles?
“Extremely contagious.” “Insanely contagious.” “One of the most highly contagious diseases known to science.”
The infectious nature of measles can be described with a host of adverbs — or a variety of numbers.
For example, measles is so contagious that a single infected person can infect up to 90% of vulnerable people in close proximity.
Or, consider the measles’ “R nought" value. R nought, denoted R0 and known as the “basic reproduction ratio,” estimates how many people are likely to become infected through contact with one infected person.
The higher the R nought value, the more contagious the disease and the more difficult it is to contain.
Polio, smallpox and rubella have R nought values between 5 and 7. In other words, one sick person would, on average, infect 5 to 7 people in a totally vulnerable population.
The R nought for measles? The 12 to 18.
Actually, recent research has determined the range is wider, depending on human behaviour in a particular region, but all evidence points in the same direction: a single measles case demands an urgent public-health response.
The measles virus resides in the nose and throat mucus and is launched airborne via a cough or sneeze. The virus can survive in the air for up to 2 hours. So long after a measles patient leaves behind an infectious cloud of virus, a susceptible person entering the space can become infected by inhaling the contaminated air.
What’s more, measles patients are infectious for up to 4 days before the telltale rash appears. Most patients are out and about infecting others before they know they are ill.
Part 2 coming soon.