Why one case of measles is a public health emergency
When studying for my Certification in Infection Control exam, a review question was “One case of this disease is a public health emergency.” The correct answer was “measles” (Rubeola). Not so for chicken pox or pertussis or rubella, so why measles? I could find no succinct answer to the question, and I had never once dealt with measles in over 10 years of nursing in pediatrics, family medicine, infection control, or public health.
In mid-December of 2014, an infected traveler visited Disneyland while contagious. For the next 4 months, health departments in southern CA (including the one where I work) would be overrun with measles cases, suspect cases, and case investigations, and I would come to better understand the emergent nature of measles.
Why is one case of measles a public health emergency?
The short answer is threefold: Measles can cause significant illness and death, is highly contagious, and we don’t want it to gain a foothold again in the United States.
First, measles can be deadly if it reaches the wrong person, and have serious complications for people who it does not kill. 25% of those who get measles will need to be hospitalized, and 1-2/1000 cases will die, despite the best care. Another 1/1000 will get encephalitis (swelling of the brain) that can lead to seizures, permanent brain damage, blindness or deafness. Measles continues to be one of the leading causes of death worldwide, particularly for young children. In 2013, there were 145,700 measles deaths, about 400 people/day.
Measles is most dangerous for people under 5 years, over 20 years, or with immune compromise. Pregnant women are at risk for premature birth of their infants. The most common cause of hospital admission and of death from measles is pneumonia. Ironically, the same people who cannot be vaccinated with the live vaccine are the people most at risk from serious complications of measles–infants under 1 year, pregnant women, and people with compromised immune systems like 7 year old-leukemia patient Rhett Krawitt of California.
In addition to dangerous short-term effects, there are life-threatening long-term effects of measles, including risk of death from many other pathogens. One theory is that measles causes “immune amnesia” where it wipes out the memory cells that make antibodies against other diseases. This leaves people vulnerable to death from all infectious causes like pneumonia or diarrhea. When researching a recent story about Shigella, I found that one of the biggest risk factors for dying of shigellosis (which kills 700,000 people/year worldwide) is having had measles.
Second, measles is highly contagious. 90% of non-immune people in close proximity to a case will be infected. The virus is small enough to linger in the air, but can also live on surfaces for 2 hours after the infected person has left the area. This means that casual contacts can be infected–people who were in the same store, the same movie theater, the same Urgent Care waiting room not only during the time the person was present, but for 2 hours after they left. The infectious period is 9 days–4 days before the rash onset, the day of rash, and 4 days after the rash. Because the rash does not show up until day 5, people generally do not even suspect that they have measles for the first 4 days of communicability.
By the time a suspect measles case is identified, there can be tens to hundreds of people who need to be notified and treated as immediately as possible. Measles vaccine must be given within 72 hours to prevent infection in the non-immune; immune globulin (antibodies, generally given to people who cannot be vaccinated or to people who it is too late to vaccinate) needs to be given within 6 days after exposure to be protective.
Because suspect cases are often caught on Day 5 or later, precious time has been lost and the need to perform contact investigations and protect the public takes on an urgency and scope that can quickly overwhelm public health departments. Public health staff must obtain and review immense amounts of data like immunization records, measles test results and titer results to assess for immunity. For close contacts who cannot establish immunity, numerous quarantine orders are issued for the 21 day incubation period.
This can potentially involve contacting, reviewing records, drawing titers, quarantining, vaccinating and giving immune globulin to hundreds of people who may have been exposed…per suspect case. The expense in work hours and taxpayer dollars is high. Forbes magazine states that, in 2011, the “… cost of 107 cases spread across 16 outbreaks cost local and state health departments an estimated $2.7 million to $5.3 million… involved contacting somewhere between 8,900 and 17,450 individuals, which required 42,000 to 83,000 personnel hours.”
Third, measles in no longer endemic to the United States, and we should try to keep it that way for all of the reasons discussed above. Measles was declared “eliminated” from the United States in 2000. Measles infections in the U.S since 2000 have been introduced from elsewhere in the world. It is estimated that worldwide efforts to vaccinate, collaboratively begun in 2001 prevented an estimated 15.6 million deaths from 2000-2013, reducing deaths from measles by 75%.