Friday, June 05, 2015

MERS: Still More Questions Than Answers

# 10,150

We are coming up on the third anniversary of the discovery of the MERS coronavirus by Dr. Ali Mohamed Zaki - who revealed the first  Saudi case in a letter to ProMed Mail - and was subsequently fired for his efforts.

Since then more than 1,000 cases have occurred on Saudi soil - and while a proper case-control study has been long promised - so far one has not seen the light of day. 

As a result, there is a lot we don't know about this emerging coronavirus (see WHO EMRO: Scientific Meeting Reviews MERS Progress & Knowledge Gaps).  Prime among them are how the virus manages to spread (albeit, not terribly efficiently) in the community, and why nosocomial spread is so hard to contain.

The silver lining in the Korean outbreak is that we are likely to learn more over the next few weeks about this virus than we have over the past three years.  

First some excerpts from a VOA News report on concerns over the spread of the virus, then I'll return with a list of some of the things we will be looking for over the next week or 10 days.

Newest MERS Cases Raise Fear of Containment Breach
        Brian Padden
June 05, 2015 5:47 AM

In South Korea four deaths related to the Middle East Respiratory Syndrome (MERS) have been reported and the number of infections rose to 41 on Friday. Two of the newest reported cases are raising concerns that the deadly virus may have spread beyond the more that 1,600 people who have already been quarantined or isolated.

MERS patient number 35 is a doctor who reportedly attended a housing conference and medical seminar in Seoul while he was in a contagious stage, potentially exposing over 1,000 other people also at the conference. 

Moon Hyung-pyo, the South Korean Minister Health and Welfare, said on Friday the ministry received a list of conference attendees and will investigate. 

He said they are preparing to impose proper measures, including isolation, after they complete the investigation. 

Patient 37 is a South Korean Air Force sergeant who tested positive for MERS at the Osan military base, located 50 kilometers south of Seoul. About 100 people in that area have been asked to stay at home. The U.S. Air Force also has a large contingent of military personnel stationed at the Osan base but so far no American personnel there have been affected.
These two cases however indicate that the deadly MERS virus could have been spread to a much wider population than the 1,600 people who have already been identified and isolated. 


Professor Choi Bo-yul with Hanyang University’s department of medicine is part of South Korea’s national MERS taskforce. He said 25 MERS cases can be traced to that hospital and an investigative team has recently found the virus in Patient 1’s hospital room and even in the air conditioning filters. 

Choi said they took out five filters from the room and sent them to the Korea National Institute of Health for testing. Out of the five filters, he said, the virus was found on three.

(Continue . . . )

I included the excerpt regarding the discovery of the MERS virus on patient #1's air conditioner filters because the Korean press has been making a lot of possible spread of the virus via the hospital's air conditioning system.

The detection of fragments of MERS-CoV (likely using RT-PCR testing) in the environment - while interesting - doesn't tell us whether or not  the virus was viable (or for how long). 

While the MERS outbreaks in the Middle East haven't suggested a `classically airborne' virus like  influenza or measles, droplet spread over short distances through the air is assumed and limited airborne transmission seems possible.

We have seen some evidence of the possible aerosolization of the MERS virus in the past (see mBio: Airborne Fragments Of MERS-CoV Detected In Saudi Camel Barn).  

In MERS: A Focus On Fomites?, we looked at another possible form of environmental transmission of the virus via contaminated inanimate objects.

A study called Stability of Middle East respiratory syndrome coronavirus (MERS-CoV) under different environmental conditions by  N van Doremalen1, T Bushmaker1, V J Munster found, under favorable temperature and humidity conditions (such as you might find in an air conditioned hospital), the MERS virus survives quite well on surfaces, and in the air.

This may help explain the high rate of nosocomial outbreaks we’ve seen with this virus.

There has been a lot of talk about a `Korean Variant' of the MERS virus - and while there is no evidence to support that yet - over the next couple of days genetic sequence data should tell us if anything has changed with the virus.

Of course, seeing a change, and understanding how it affects the behavior of the virus are two different matters. 

More importantly, with an incubation period of 14 days, we should know over the next week or 10 days whether the virus has truly entered the community.  For now, cases all appear linked to the hospitalized cases - and if that remains the case - this outbreak should be containable.

Of course, should Korean hospitals start seeing `walk-in' cases without any obvious exposure history, then things become considerably more complicated.

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