Over the last several months, I've been peppered with questions from folks wondering what to make of the latest viral threat: Middle Eastern respiratory syndrome, or MERS. Is it all headline hype, or is it worth a little worry? And with news of cases now in Europe, are there special considerations for those whose summer plans involve crossing the Atlantic?
The best way to fight fear is facts. Cases of the acute respiratory illness — caused by a previously unknown virus — continue to climb. The illness gets its name because the first cases were isolated in Saudi Arabia, and the majority have since occurred in that region. To date, there have been 55 cases recognized, of which 32 (58 percent) have proven fatal. And although most have occurred in the Middle East, there have been a handful in returning travelers to England, France and Italy. Several are the result of person-to-person transmission, some of which occurred in health care settings.
But what is MERS? The virus belongs to an extended family called the coronaviruses, because under the electron microscope they appear to be surrounded by a halo, or crown. Though the name sounds scary, coronaviruses are actually common causes of colds and mild respiratory illnesses, and all of us have experienced coronavirus infections at some time. But the new virus is clearly capable of causing much more severe, even fatal, respiratory illness — even in previously healthy persons.
Where does MERS come from? Like other recent infectious disease threats (e.g., bird flu, Hendra and Nipah viruses, and SARS), MERS appears to have originated from animals. Interestingly, viruses very similar to MERS have been isolated from a variety of bat species. And though that might sound like the opening scene of a superhero movie, there are slight (but important) differences between bat coronaviruses and the MERS coronavirus. Also, generally victims of MERS have not had known exposures to bats, so there's probably an unidentified intermediary animal (something that passes the disease between bats and humans). The obvious question, of course, is how these viruses jump the species barrier, and if they could eventually adapt to become a more widespread pathogen in humans. So far, that risk appears low — but that assessment could change as more information becomes available.
So, for folks bound for European vacations: Will MERS throw a wrinkle in your plans? Probably not. The Centers for Disease Control (CDC) recommends that persons who develop severe acute lower respiratory illness within 14 days after traveling from the Arabian Peninsula or neighboring countries should be evaluated for MERS, and managed in a health care setting in respiratory isolation. And while the World Health Organization and CDC have not issued official travel advisories at this time, if you are planning travel to affected countries in the Arabian Peninsula, it's always smart to do a final check for updates before heading abroad.
John Treanor, M.D., is a professor of medicine, microbiology and immunology, and serves as chief of the Infectious Diseases Division of the department of medicine at the University of Rochester's School of Medicine and Dentistry.