APR 17, 2019 8:50 AM PDT

During an Ongoing Outbreak, a Look at Why Measles is Highly Contagious

WRITTEN BY: Carmen Leitch

Measles is extremely contagious, and this year, the Centers for Disease Control and Prevention (CDC) has found that it is still spreading in the United States. Outbreaks are defined as three or more cases, and right now, there are outbreaks in New York, Washington, New Jersey, California, and Michigan. Twenty states in total around the country have reported cases so far in 2019. The 555 reported individual cases marks the greatest number of infected individuals reported in one year since 2000.  Countries such as the Philippines, Israel, and Ukraine are currently experiencing widespread outbreaks of measles, and the cases in the US are thought to be connected to travelers who have brought the disease back with them after visiting those places. The CDC advises people to get vaccinated, especially if going overseas.

Humans spread measles, which lives in the throat and nose of infected individuals. Just by coughing or sneezing, they can infect others. The virus that causes measles can survive in the air for up to two hours after an infected person has sneezed or coughed. Just by breathing that contaminated air, other people can become infected. People can also pick the virus up by touching surfaces that carry the virus and then touching their nose, eyes or mouth. The CDC cautions that measles is so pathogenic, an infected person can spread the illness for four days after their rash first appears, and will go on to infect as many as ninety percent of people nearby them who are not immune.  

Animals and asymptomatic individuals have not ever been found to spread measles. References to the illness go back to the seventh century, and a Persian physician named Rhazes described measles as “more to be dreaded than smallpox” in the tenth century.

Infection with measles was once a rite of passage; about ninety percent of people gained immunity to the illness because they had been sickened by it before the age of fifteen. It is still a fatal disease that is dreaded in many developing nations; it caused 145,700 deaths around the world in 2013, according to the World Health Organization (WHO). 

Before 1963, about 500 deaths were caused by measles with about 500,000 sickened in the US every year (although it may have been as high as four million in some years). The first vaccine was introduced in 1963, cases dropped by 95 percent, and the epidemic cycles that happened every two or three years stopped. It seemed for a time that the disease could be eliminated.

A digitally colorized, thin-section transmission electron microscopic (TEM) image depicting the ultrastructural appearance of a single measles virus particle, or virion. / Credit: CDC/ Cynthia S. Goldsmith; William Bellini, Ph.D.

In recent years, progress against the virus has stalled and cases have begun to appear again, primarily in communities that are not vaccinating members. An Orthodox Jewish community experienced an outbreak in 2018; travelers returned from Israel with the disease. A small community of Somali-Americans that had not been fully vaccinated reported 75 cases in 2017. It’s thought that an infected person visited a California amusement park in 2015 and spread measles to 147 people there, though that was never conclusively confirmed. A large outbreak occurred in an Amish community in 2014; many outbreaks happened that year, which were linked to a measles outbreak in the Phillipines.

Vaccines are safe and effective but work best when a whole community commits to its safety by ensuring everyone gets vaccinated. WHO has named vaccine hesitancy as a major threat to public health.

Sources: CDC, WHO

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
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