Once effectively eliminated in the U.S., measles is making an unwelcome comeback. The virus is now responsible for 121 cases in 18 states plus the District of Columbia. All but 18 of these cases can be traced directly to the outbreak that began at Disneyland in December. More contagious than smallpox, polio, or the flu, measles is a serious and highly contagious disease —and it is not to be taken lightly.
Since making contact at the Disney amusement park, the measles virus has been able to spread because of the growing number of unvaccinated people in the U.S. In California, in particular, a higher percentage of the population is not vaccinated because California is one of 19 states that allows parents to refuse vaccinations. Last year in California, 3.3% of kindergarten students—roughly 18,200 children—were not vaccinated, according to the Centers for Disease Control (CDC). Personal beliefs are the primary reason for refusing vaccines.
According to Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), the majority of people infected with measles in this recent outbreak had not been vaccinated. Those affected range in age from 7 months to 70 years. Roughly one in four have had to be hospitalized.
Measles is an acute viral respiratory illness that spreads rapidly through contact with infectious droplets either in the air or on contaminated surfaces. Because it is so easily transmitted, 90% of unvaccinated persons who come in contact with measles become infected. Symptoms include fever as high as 105°F, cough, conjunctivitis, and a rash that appears usually two weeks (but up to 21 days) after exposure. Those infected are contagious four days before the rash appears. Common complications from measles include bronchopneumonia, laryngotracheobronchitis, and otitis media. Up to 2% of pediatric cases die from respiratory or neurologic complications. Those at higher risk for severe illness and complications include infants and children under age 5, pregnant women, and people with compromised immune systems.
Back in the Day
Until a vaccine was available, about 3 to 4 million people became infected with measles each year in the U.S. About 500 of them died and 4,000 developed encephalitis. With the advent of the measles vaccine in 1963, the number of cases began to decline. Measles was declared eliminated from the U. S. in 2001, meaning that the virus was no longer native in the U.S. but continued to be brought into the country by international travelers. From 2001 through 2013, an average of only about 88 cases a year was reported in the U.S. Last year, that number ballooned to 644.
An Ounce of Prevention
Measles remains common in some European and Asian countries, in the Philippines, and in Africa where roughly 20 million people become infected and 122,000 die from the disease every year. Whenever an infected person enters the U.S., the opportunity to spread the disease exists, particularly if that person comes in contact with individuals who have not been vaccinated. Public health officials here rely on a highly vaccinated population to keep the disease at bay. It is what they refer to as “herd immunity,” the protection that occurs when a sufficiently high percentage of the population is vaccinated and can provide protection for those who do not have immunity. The more people who are vaccinated, the less likely it will be that someone who lacks immunity will come in contact with an infected person. Thus, if vaccination levels drop, as they have in the past few years, measles again can become a very real threat.
All public health experts agree that the best way to avoid contracting measles is by getting the measles vaccine. It is one of the most effective vaccines for any viral disease. One dose of the vaccine is approximately 93% effective in preventing measles; two doses are approximately 97% effective.
A Little Persuasion
If there’s any good news, perhaps it is that the measles outbreak may persuade more parents to have their children vaccinated. Until now, an estimated 1% to 3% of parents in the U.S. are opposed to vaccinating their children. People who are against vaccinations believe that the risk of the vaccine is so great that it negates any benefit the vaccine could provide. However, any arguments that these “anti-vaxxers” have offered about the adverse effects of vaccines has been disproven by a number of independent scientific groups.
Even if scientific evidence won’t change the minds of those staunchly opposed to vaccines, it may persuade another group—“vaccine-hesitant” parents—those that have doubts and skip or delay some shots beyond their recommended schedule. Vaccine-hesitant parents account for between 5% and 11% of parents in the U.S. If public health officials are able to sway a significant portion of these parents, the resulting increase in the vaccination rate could take a big bite out of the measles threat. Researchers are trying to determine what triggers fears about vaccinations to create strategies that will help overcome them.
Additional information about identifying and treating measles for health care professionals is available from the CDC. The CDC has also issued a Health Alert Advisory to provide guidance for health care providers.