Measles outbreak hits adults hard, defying reputation as childhood malady
The measles outbreak that heralded a year of epidemics began in the usual manner. An overseas traveler brought the virus back to a community in which many parents do not vaccinate their children. The disease spread within the cloister before radiating outward.
In this case, in January, a visitor to Eastern Europe returned to southwest Washington state, where a large number of Slavic-Americans reside. Unvaccinated children circulated the illness, and with their county just across the state line from Portland, the contagion carried to Oregon, too.
Including other exposures—notably here in the North State, New York and New Jersey—this year marks the second-worst for measles since it was declared eradicated in 2000, with around 465 cases reported nationwide as of the CN&R’s deadline.
Butte County Public Health announced the sixth local case Monday (April 8). This patient, like the first four diagnosed, is an adult—only one is a child.
In fact, most of California’s measles patients this year have been adults, 12 of 19. That’s unusual; most years since 2013, the numbers have split comparably between youths and adults. (In 2017, the last year of state statistics, California had 54 patients ages 19 and under versus 47 ages 20 and over.)
The disease is virulent but preventable. As Dr. Linda Lewis, epidemiologist for Butte County Public Health, explained, “the measles vaccine is one of our most effective vaccines.”
MMR—a combination vaccine for measles, mumps and rubella—has 97 percent effectiveness with two doses and 93 percent with one dose at preventing measles, according to the U.S. Centers for Disease Control and Prevention. It dates to 1963, and in 1968 was improved.
People got vaccinated for three decades with little controversy until a study suggested MMR caused autism. Long since debunked, that 1998 report authored by former British physician Andrew Wakefield sparked a 21st century anti-vaxx movement, which has contributed to measles outbreaks among schoolchildren. (Wakefield is prohibited from practicing in the UK.)
That doesn’t account for people over 20, though, who predate the Wakefield hype.
So, who are these adult measles patients, and why aren’t they protected?
First, let’s dispense with a stereotype. Just because measles comes from abroad, carriers are not necessarily undocumented immigrants, as certain political partisans push.
Dr. James Watt, chief for the Division of Communicable Disease Control of the California Department of Public Health, told the CN&R that travelers often account for measles in the state. Californians may bring it from countries where it’s still active, such as the Philippines. Tourists to California may bring it when visiting.
Some may be vaccinated, some not.
“There are some people who get vaccinated and do not develop immunity,” Watt explained. “No vaccine is 100 percent effective. Somewhere around 2 [percent] or 3 percent of people who get vaccinated may be susceptible to measles.”
That percentage could be higher in middle-aged adults. In 1990, with more than 55,000 cases reported over two years, the medical community re-examined the measles vaccine schedule. The recommendation for MMR doubled to two doses that decade.
“With a single dose, there’s a larger proportion of people who will not respond to the vaccine,” Watt said. “So [adult patients] may be some folks who are in their 40s now … or may have been children at a time when there were some access issues.”
Medical conditions prevent certain people from receiving vaccinations, such as those with deficiencies of the immune system. For others, traditional beliefs hold sway.
“If you’re talking about people who are foreign-born,” Lewis said, “in different countries, [there can be] a distrust of vaccines and of government, and that was the situation in the Washington state recent outbreak [of 78 cases]. And they were not illegal immigrants—they were legal immigrants. New York state [with 167 cases this year]—that was members of an ultra-Orthodox Jewish group; the [overarching religious] organization does not eschew vaccines, but subgroups within it do.
“The common denominator is some kind of mistrust of vaccines that’s based in nonscientific information.”
In any case, the disease is highly contagious. The virus lives in mucous membranes of the nose and mouth. It spreads through sneezing and coughing—and can survive two hours in the air after a sneeze or cough. Symptoms can take 14 days to show.
The illness typically starts with a fever that, after several days, progresses into a cough, runny nose, rash and pink eye. Measles can prove fatal and has no treatment. At highest risk for infection and serious complications are children under 5, adults over 19, pregnant women and anyone with an immune deficiency.
“The disease is definitely of much greater risk to somebody’s health than the vaccine,” Lewis said.
Epidemiologists consider measles “eliminated” in the United States—getting that designation in 2000. This doesn’t mean the disease has been totally eradicated, like smallpox, which doesn’t exist anywhere. Rather, measles doesn’t occur continuously here, only breaking out when imported.
“Most people in America have not seen measles,” Lewis said. “And, so, there’s this kind of notion that everybody used to get it and it’s no big deal. But it can be a big deal, especially for the very young and those who are immuno-compromised.”
The concept of herd immunity resonates for Lewis. That refers to the percentage of the population needing to develop immunity to a disease in order to prevent its spread. For measles, that’s 93 percent to 95 percent, according to the World Health Organization.
A segment of adults—and children—have no choice about vaccination because of their health. Also, immunized patients with life-threatening diseases such as cancer take medications (e.g., chemotherapy) that weaken their immune systems.
“We all have some responsibility to our community,” Lewis said, “and we have an increasing number of people who are immuno-compromised, because medicine has gotten better at keeping people alive with underlying conditions…. They rely on the people around them being vaccinated and interrupting transmission to protect them from measles.”