Sunday, 7 June 2015

South Korean MERS cluster keeps growing..

version 3.
This cluster of hospital-related infections in South Korea has now reached 64 Middle East respiratory syndrome (MERS) cases. And no camel meat or milk, no route of ingestion yet fond in fact not even a camel to be seen - except the ones quarantined in the South Korean zoo - I can't even....

Anyway, thanks to a week long internet outage in my house (yes, I do these blogs from home) I've been unable to blog on any of this. 

Surprisingly though, after a week, the cluster is still going pretty strong. The recent tallies include 6 cases then 5, then 5, then 6, 9 and last night 14. These include 5 deaths (10%). 

As you'll see from the first 11 cases I've plotted below, this is similar to a bunch of incidents we've followed in Saudi Arabia in 2013 to today (Hafoof seems to have a pretty good cluster going at the moment). They have usually been the result of poor infection prevention and control creating a perfect storm of circumstance for viral spread. 

Timelines of the first 11 cases of MERS-CoV infection in South Korea.Click on image to enlarge based on World Health Organization and  FluTrackers information with help from this timeline. Hospital names have been published here and here - I'm not sure if this is how they are ordered so please consider this a work in progress.
Click on image to enlarge

It's looking like this will be the case in South Korea too. 

A couple of interesting things to note:

  1. Cases are still popping up - a month later
  2. A viral genome sequenced in China (ChinaGD01), from a South Korean case that flew out of South Korea to Guangdong, does not show any obvious genetic differences compared to other MERS-CoV genome sequences. Its sequence identity falls in the range that we can fit around all the MERS-CoV genomes - whether from humans, camels, from Saudi Arabia, Qatar or the United Arab Emirates, 2012 or 2015.
  3. MERS cases in South Korea are tightly linked to hospitals - healthcare workers feature prominently as do other "close contacts" including relatives who stay at the hospital to help care for their loved ones. There are no indications of escape outside those hospitals so the closing of schools, the wearing of masks (which don't cover eyes) and the increased border measures offered to North Korea have no support from science or facts
  4. Some incubation times are pretty short - just 3 or 4 days between exposure (in whatever form that is taking) and symptom onset - yet we haven't seen any not-so-close contacts come down with infections, despite that same time frame having passed long ago for them.
    Spread of virus is not very different to what we've observed in Saudi Arabia for 3 years
  5. A few people have called the index case a "super-spreader" because of all the contacts he's had that have developed MERS (what about those who haven't developed disease by the way, are they being tested?) - I've come to loathe that term. It lazily defines the person as super-spreader while ignoring the context in which that person has been managed - namely whether infection control measures are well used, or in place at all. A super spreading event I like a little more - but even that makes something, special scary or different  out of what may be something completely normal in infectious disease biology
  6. Testing times are all over the place - in just those first 11 cases it could be 9 days before a test result confirmed MERS-CoV infection. Therein may lie a reason for why MERS cases are still appearing now - no-one knew then, nor for a decent while, what they had. Although...they did know that they had an acute respiratory infection and I can't for the life of me work out why these viruses seem to get away from us time and time, and time again. Well, yeah I do - it's because people.

"Are we ready for the next pandemic?" is a question that has been asked a lot since the peak of the peak of Ebola virus disease epidemic in West Africa. The answer is that there is no way in a million years we're ready.

Version history.
  • v2-fixed graphic's transparent background & changed case tally from 50 to 64
  • v3-added in hospital names and a few more cases.