MERS Storms the Korean Peninsula

As the outbreak of MERS cases in South Korea continues it appears that what is responsible for the 30--2 of which have been fatal and one of which was imported to China--is a combination of lax infection control coupled with a possible super-spreader event. This camel and bat-linked coronavirus, which has killed about 36% of the 1200 people it has infected thus far, has now been reported in 16 nations (including the US for those of you who have forgotten). 

To recap the events: mid-May a man who traveled to the MERS epicenter, the Middle East, returned to South Korea and was subsequently diagnosed with MERS. Being the 1st MERS case in South Korea and with a consequent delay in diagnosis patient's who were co-located were exposed and infected (primary transmission) then went on to infect others (secondary tranmission) who then went on to infect others (tertiary transmission, which has been confirmed in 2 cases).

This cluster, which is exclusively hospital-based thus far, has vaulted South Korea to the #3 MERS country, behind Saudi Arabia and the UAE.  Such a cluster reinforces the need for meticulous infectious control when dealing with a respiratory virus like MERS that has proven adept at exploiting lapses in infection control. South Korean authorities have since apologized for their handling of the initial stages of this outbreak which have led to over 1300 people being monitored after contact with case patients. 

Also, the index patient is responsible for infected at least 11 (maybe 22) other individuals (Ro = 11 - 22) clearly putting this man in the category of a super-spreader as his disproportionate contagiousness has clearly fueled this outbreak (similar to what occurred with the related SARS in 2003).

These events have, understandably, provoked fear in the South Korean populace and have prompted school closures as well as a travel alert in Taiwan. 

It is important to remember, at this stage, that no community transmission has occurred in South Korea and, though it is a possibility, swift action on the part of public health authorities can extinguish the outbreak. What also must be emphasized to clinicians world-wide is that MERS (and other infectious diseases) can appear anywhere and, to paraphrase Louis Pasteur, prepared minds are the ones that are lucky enough to discover them before too much damage is done. 

Lost in the Ebola & EV-D68 News Cycle: A Promising MERS Vaccine

With Ebola and EV-D68 garnering all the attention, it's not surprising that people have forgotten about MERS. Thankfully, the research community hasn't stopped working to combat this virus that has just gone on a 3-day run of accruing cases in Saudi Arabia.

So, while the world is watching Ebola colleagues at the University of Pittsburgh, led by Dr. Andrea Gambotto, recently published results of a promising vaccine candidate in Vaccine. 

In this study, an adenovirus-MERS recombinant virus (of note, adenovirus-vectored vaccines against Ebola are being studied too), was used in mice and antibodies level measured. The vaccine succesfully provided robust levels of antibodies against the MERS coronavirus, an important correlate of immunity.

What is interesting about this vaccine study is that one of its explicit goals is to create a vaccine that could be used in the animal species responsible for transmitted the MERS virus to humans, presumably camels. It's not an unprecedented idea; we immunize many animal species against rabies and a very select number of humans receive the vaccine. Removing the transmission mechanism of this virus could obviate the need for large scale human vaccination.

It may be difficult to keep up with all the emerging threats and track all the zebras, but we ignore them at our own peril. To echo Dr. Gambotto's statement to the Pittsburgh Post Gazette--"we want to be pre-emptive” against MERS, and all emerging infectious diseases. 

Unsolved "MERSteries"

The announcement of the 2nd domestic MERS case today is not surprising and doesn't represent a major change in the pattern of cases. This case, like the one before it, is in a traveling healthcare worker and its detection reinforces the importance of astute clinicians armed with the knowledge and tools to detect emerging viruses.

However, in light of this case, lingering questions should be revisited given the smoldering nature of this 2 year plus outbreak.

Do super spreaders exist?

The most dramatic feature of SARS was the existence of super spreaders. These Typhoid Mary like individuals were responsible for much of the global spread of SARS. With MERS however, evidence of super spreaders has not been definitively established although events suggestive of such spread exist. For example, in Abu Dhabi there is an case patient who may have been responsible for secondary spread to 27 additional cases. It is unclear, according to the WHO (at this time), whether these were all linked transmission events or from non-human sources. Additionally, the Al Hasa outbreak detailed in the NEJM is also suggestive. 

I think that for all infectious diseases, super spreaders likely play a major role and MERS will turn out to be no different. 

Is This a Public Health Emergency of International Concern?

The International Health Regulations provide WHO with a mechanism to declare a public health emergency of international concern (PHEIC) when events reach a certain threshold. The WHO is convening a meeting tomorrow to determine whether MERS meets that criteria. I think this is a difficult decision because, in a way, MERS has met this criteria over the last 2 years and nothing fundamentally different has occurred (granted the uptick in cases). Prior meetings have not resulted in such declarations.  However, a PHEIC declaration may provide an impetus to countries with cases to provide more information about cases and the means by which they were infected. 

Little Pink Houses and MERS in Indiana

The just revealed news of an imported MERS (Middle East Respiratory Syndrome) case in Indiana--the first in the US--is not surprising. 

MERS has been simmering for 2 years and importations have occurred to several countries, including the UK. 

In this case, an infected healthcare worker (not surprisingly) traveled from Riyadh to London and on to Chicago. The patient then boarded a bus to Indiana.  

Although MERS has a case fatality rate of 30%, this patient appears to be not critically ill. Important actions in the coming days will include searching for secondary cases.

This case illustrates 2 important things:

1. It's a small world and infections on one side of the globe can appear on the other with no border restriction string enough to stop it. 

2. Astute clinicians are crucial. From what I've read, the patient's travel history tipped off physicians who ordered the appropriate tests. 

MERS occurring in the US was something that was expected and planned for--remember 8 SARS cases occurred in the US as well.