Asymptomatic MERS has been a hot topic lately.
Since the onset of the current outbreak, 22% of all reported diagnoses – 60 of 279 total – have been asymptomatic. Of those 60, over half of them have been healthcare workers (HCW) .
In fact, the data thus far indicates that healthcare workers are far more likely to have asymptomatic MERS than members of the general public. 32 of the 69 healthcare workers that have been diagnosed since March 20th have been asymptomatic .The pervasiveness of asymptomatic MERS in healthcare workers is troubling – and potentially dangerous – for a number of reasons. Long story short: while healthcare workers seem to be somewhat protected from death-by-MERS, the sick (read: co-morbid) patients that they care for are not. Since MERS was first documented in March 2012, a whopping 33% of co-morbid individuals who contracted the virus died. Compared to 7% among healthcare workers, that’s a pretty substantial difference in fatality risk . Needless to say – if asymptomatic healthcare workers can shed the virus, this seriously compromises the safety of the hospital environment. It may also – to some degree – explain the large number of nosocomial (hospital) transmissions the World Health Organization cited in their most recent MERS-CoV risk assessment.
But this still leaves us wondering: how?
Even if we assume that asymptomatic cases – healthcare workers and otherwise – can shed the virus, it would theoretically be much harder for them to actually transmit it. Without respiratory (or in some cases, gastrointestinal) symptoms – such as sneezing, coughing, etc. – how would the infected droplets (that seem to be) necessary for transmission make it out of the body?
For the time-being, my money’s on ritual ablution.
Now, this is most certainly a scientific wild-ass guess (#SWAG), but it may actually have legs. Here’s why:
1. In the Islamic world, nearly every person practices ritual ablution (wudu) – 5 times a day, every day. This is especially the case for Saudi Arabia, where the vast majority of the population engages in daily prayers – even during working hours.
2. Thoroughly rinsing the mouth, ears, and nasal passages are compulsory components of wudu. In theory, this could allow expulsion of the virus from the body.
3. We found out several months ago that MERS-CoV can remain infective on and be transmitted by fomites for several hours (or up to 2 days!) after discharge. In this case, we’re considering surfaces like basins, faucets, handles, etc.
4. And finally, the kicker: ritual ablution typically takes place in a shared washroom. I think the relevance of this piece of information is pretty self-explanatory.
So, is this theory a little crazy? Absolutely; that’s what #SWAGs are all about! But at the same time, it’s contextually relevant and logically defensible, given what little we know so far about MERS in Saudi Arabia. If nothing else, it gives us a different way to approach this particular phenomenon.
With this in mind, I think it would be wise for Saudi hospitals to take a closer look at surfaces in shared staff washrooms. Who knows? They might be surprised by what they find under the microscope.
Note: Temporal data indicates date of onset, hospitalization, diagnosis, or public reporting.
Data Sources: KSA MoH & WHO