Catching (up with) MERS

Today a MERS case was announced in another country — Italy, where the patient is a man who recently traveled to Jordan (it’s being reported that one of his sons there has similar symptoms). This makes at least fifty known patients with greater than 50% mortality rate. Time to introduce our latest potentially large-scale viral adversary.

Middle East respiratory syndrome coronavirus (MERS-CoV) is one of several coronaviruses humans contract.  In fact, about 30% of cases of the “common cold” are caused by coronaviruses, but with  coronaviruses SARS and MERS, the illness can be far more severe.  Under the electron microscope, MERS looks like this:

Image source: Cynthia Goldsmith/Maureen Metcalfe/Azaibi Tamin, via

Image source: Cynthia Goldsmith/Maureen Metcalfe/Azaibi Tamin, via

It’s deadly.  As of May 29th, the WHO knew of 49 confirmed cases and 27 deaths. That’s a 55% mortality rate compared to the <10% rate of SARS.  (Reuters today says 51 patients with 30 deaths: 58% mortality.)

It can progress quickly. This slide from an article in the New England Journal of Medicine shows the rapid change in four patients, a family cluster of four men who became sick last fall. Two of them died.

We don’t know where it came from, how it can be transmitted, or much else.  The assumption is that there’s an animal source, but that hasn’t been found.  We know it can be transmitted from person-to-person, but not exactly how that happens or how contagious MERS is.  Those aren’t the only puzzles. As Laurie Garrett wrote about the case above, “The cluster of cases in this family presents a list of mysteries: Why were all the sick and dead men? With 28 people in this three-building urban household, why were these four infected, and the other 24 spared? The family lived in a big city, had no animals, ate supermarket food and had jobs that offered no contact with the virus. How did they catch MERS?”

The incubation period may be substantial.  A study of French cases of MERS released online by The Lancet yesterday estimates one incubation period as 9-12 days. This calls for longer isolation than expected and raises the risk that the virus will spread as people who don’t yet feel sick travel.

It’s centered in a troubled area.  It’s called Middle East respiratory syndrome for a reason: all currently known cases originated there (one transmission is known to have taken place outside of that region, but from a patient infected there). Millions of Syrians have been displaced during their civil war and many refugees are crammed together in camps, like this one in Jordan that was featured on yesterday’s PBS Newshour.  If the virus were to get a foothold in a place like that, it could quickly overwhelm the medical resources for refugee care.