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Measles: A dangerous vaccine-preventable disease returns

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Release date: June 1, 2019
Expiration date: May 31, 2020
Estimated time of completion: 1 hour

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ABSTRACT

Although a safe and effective vaccine has been available for over 6 decades, vaccine hesitancy in the United States and social and political unrest globally have led to undervaccination. As a result, in recent months, vaccine control of measles has been threatened with an alarming upswing in measles cases nationally and internationally. Here, we review the disease and its management in view of recent outbreaks.

KEY POINTS

  • Measles is highly contagious and can have serious complications, including death.
  • Measles vaccine is given in a 2-dose series. People who have received only 1 dose should receive either 1 or 2 more doses, depending on the situation, so that they are protected.
  • The diagnosis of measles is straightforward when classic signs and symptoms are present—fever, cough, conjunctivitis, runny nose, and rash—especially after a known exposure or in the setting of outbreak. On the other hand, in partially vaccinated or immunosuppressed people, the illness presents atypically, and confirmation of diagnosis requires laboratory testing.
  • Management is mostly supportive. Children—and probably also adults—should receive vitamin A.
  • Since disease can be severe in the unvaccinated, immune globulin and vaccine are given to the normal host with an exposure and no history of vaccine or immunity.


 

References

Measles, an ancient, highly contagious disease with a history of successful control by vaccination, is now threatening to have an epidemic resurgence. Until recently, measles vaccination largely controlled outbreaks in the United States. The Global Vaccine Action Plan under the World Health Organization aimed to eliminate measles worldwide. Nonetheless, the vaccine refusal movement and slow rollout of vaccine programs globally have interfered with control of the virus. A record number of measles cases have emerged in recent months: more than 700 since January 2019.1 Approximately 70% of recent cases were in unvaccinated patients, and almost all were in US residents.

This update reviews the history, presentation and diagnosis, complications, management, contagion control, and emerging threat of a measles epidemic. It concludes with recommendations for clinical practice in the context of the current measles outbreaks.

FROM UBIQUITOUS TO ERADICATED—AND BACK

Before the measles vaccine was developed and became available in the 1960s, outbreaks of measles occurred predictably every year in the United States and other temperate regions. During yearly outbreaks, measles was so contagious that household contacts had attack rates above 95%. Most cases occurred in very young children, and because infection with the virus causes lifelong immunity, it could be safely assumed that by adulthood, everyone was immune. In an outbreak in the Faroe Islands in 1846, no one who had been alive in the last major outbreak 65 years earlier became ill, but everyone under age 65 was at high risk with “high attack rates,” estimated as 99% from other outbreaks (reviewed by Krugman et al2).

In isolated regions previously free of measles, adults did not have immunity, and when exposed, they often developed severe disease. When European settlers brought measles and smallpox to the Americas beginning in the late 15th century, these diseases decimated whole populations of native peoples who had never been exposed to them.

Figure 1. Effect of measles vaccine on incidence of measles in the United States. From the US Centers for Disease Control and Prevention.

Figure 1. Effect of measles vaccine on incidence of measles in the United States.

The wide accessibility and promotion of the measles vaccine over the last 6 decades has dramatically decreased the incidence of measles in the United States (Figure 1). The disease was declared eliminated in 2000.

That was premature. A number of outbreaks have occurred since then; the largest in the United States (before 2019) was in 2000. Over half of the 667 cases reported during that outbreak were in an underimmunized Amish community in Ohio.3

Now it emerges again.

PRESENTATION CAN VARY

Figure 2. Koplik spots arise during the viral prodrome and are critical for the clinical diagnosis of measles before the onset of rash. From the US Centers for Disease Control and Prevention.

Figure 2. Koplik spots arise during the viral prodrome and are critical for the clinical diagnosis of measles before the onset of rash.

Measles is an acute viral illness. In endemic areas or during outbreaks, measles should be suspected in a patient who has the classic triad of the 3 “Cs”: cough, conjunctivitis, and coryza (runny nose).
Figure 3. Morbilliform rash of measles. From the US Centers for Disease Control and Prevention.

Figure 3. Morbilliform rash of measles.

Koplik spots, the prodromal rash on mucous membranes such as inside the mouth, are bluish-white against a red background (Figure 2). They confirm the diagnosis for the experienced clinician before the onset of the characteristic morbilliform rash (Figure 3). The rash appears several days after the fever begins and corresponds with the immune response to the infection; it typically spreads from the head down. Extreme malaise is characteristic; in fact, children infected with measles are described as “feeling measly.”

The presentation varies somewhat among certain groups.

Nonimmune pregnant women have an especially severe course, likely related to the relative immune suppression of pregnancy.

In immune-suppressed states, measles is not only more severe, it is also difficult to diagnose because the rash can be absent.

In partially vaccinated children and adults, the disease may present atypically, without cough, conjunctivitis, and coryza, and it may be milder, lacking some of the extreme malaise typical of measles and with a shortened course. Measles infection in people who received the inactivated measles vaccine that was briefly available from 1963 to 1967 is also associated with atypical measles syndrome, a severe hypersensitivity reaction to the measles virus. Atypical measles can be prevented by revaccination with a live-virus vaccine.

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The return of measles—an unnecessary sequel

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