It is never a good sign when - by late May - the year-to-date number of measles reported in the United States already exceeds the yearly totals for any year since the turn of the 21st century. While many people think of measles as a relatively benign childhood illness, it actually produces significant morbidity and mortality with respiratory, ocular, and neurological complications - sometimes resulting in death.
During the 1950s – before the introduction of the measles vaccine – the US saw roughly 4 million infections which hospitalized nearly 50,000, and contributed to the deaths of several hundred every year.
The chart below (source: CDC) shows the remarkable effectiveness of that vaccination campaign.
By the year 2000, the number of locally acquired measles cases in the US was so low, the disease was considered to be effectively eliminated in the United States (see MMWR Measles — United States, 2011 Weekly April 20, 2012 / 61(15);253-257 - In 2000, the United States achieved measles elimination (defined as interruption of year-round endemic measles transmission)).
Just to define our terms: `Elimination’ refers to a local or regional victory over a disease, while `eradication’ indicates global success.
But between less-than-optimal vaccination rates over the past decade, and the constant importation of this highly infectious disease by unvaccinated travelers who recently visited regions of the globe that have not achieved measles control, the number of cases has begun to rise again in recent years (see NYC Health Department Investigating Measles Outbreak).
Dr. Anne Schuchat, in a telebriefing from the CDC yesterday (links below), described the situation:
To date, 15 outbreaks have been reported. An outbreak includes three or more related cases. Besides the outbreak in Ohio, other large outbreaks have occurred in New York City and California, which has responded to six outbreaks in six counties. Why are we having such a bad measles year? There are two factors. First, measles is coming in on airplanes from places where the disease still circulates or where large outbreaks are occurring. Second, imported measles virus is landing in places in the U.S., where groups of unimmunized people live. That setting gives the measles virus a welcome wagon by providing a chance for outbreaks to occur, and the larger the outbreak, the more difficult to stop. Up to 288 cases in the U.S., 280, or 97 percent, were associated with importations from at least 18 countries. This is a reminder that measles is still common in many parts of the world, including countries in Europe, Asia, the pacific and Africa.
The audio and transcript for this entire briefing has been posted at the link below:
Press Briefing Transcript
Thursday, May 29, 2014 12:00 p.m. ET
The CDC also published a press release to accompany this telebriefing:
CDC urges vaccination as summer travel season approaches
Two hundred and eighty-eight cases of measles were reported to the Centers for Disease Control and Prevention (CDC) in the United States between Jan. 1 and May 23, 2014. This is the largest number of measles cases in the United States reported in the first five months of a year since 1994. Nearly all of the measles cases this year have been associated with international travel by unvaccinated people.
“The current increase in measles cases is being driven by unvaccinated people, primarily U.S. residents, who got measles in other countries, brought the virus back to the United States and spread to others in communities where many people are not vaccinated,” said Dr. Anne Schuchat, assistant surgeon general and director of CDC’s National Center for Immunizations and Respiratory Diseases. “Many of the clusters in the U.S. began following travel to the Philippines where a large outbreak has been occurring since October 2013.”
Of the 288 cases, 280 (97 percent) were associated with importations from at least 18 countries. More than one in seven cases has led to hospitalization. Ninety percent of all measles cases in the United States were in people who were not vaccinated or whose vaccination status was unknown. Among the U.S. residents who were not vaccinated, 85 percent were religious, philosophical or personal reasons.
The large number of measles cases this year stresses the importance of vaccination. Healthcare providers should use every patient encounter to ensure that all their patients are up to date on vaccinations; especially, before international travel.
More than ever health care providers need to be alert to the possibility of measles and be familiar with the signs and symptoms so they can detect cases early.
“Many U.S. health care providers have never seen or treated a patient with measles because of the nation’s robust vaccination efforts and our rapid response to outbreaks,” said Schuchat.
Imported diseases such as measles, polio, dengue, malaria (and many others) remain an ongoing threat – even in places where they have been officially `eliminated’. Likewise, emerging diseases, like Chikungunya, H5N1, or MERS-CoV can easily expand to new geographic regions due to enhanced global travel and trade.
Photo Credit- CDC
As both the CDC and the World Health Organization continue to remind us (see The Global Reach Of Infectious Disease), pathogens are excellent international travelers. A few recent blogs on other `imported’ disease threats includes: