A busy report from the Saudi MOH today with 8 new MERS cases in Riyadh, and six deaths. Two of the new cases are listed as Health Care workers, but only one is listed as a definite contact with a confirmed case. For the 7 other cases reported today, their possible exposure is `under review’
That said, most of the 100+ cases reported over the past month have been linked to nosocomial spread of the virus in one or more Riyadh hospitals.
Since onset dates, or dates of positive MERS testing, are not provided in these daily updates we have no good idea how `current’ these reports really are. In the past we’ve seen delays of a week or more between the time a patient tests positive and their case is reported (see WHO Update On Saudi MERS Cases – August 21st).
Late yesterday we also gained a bit more insight on how the Saudi MOH regards asymptomatic MERS cases, via a twitter conversation between Dr. Hail Alabdely of the Saudi MOH, FluTrackers, Dr. Ian Mackay, and others.
The argument over whether an asymptomatic infection is a truly a `case’ notwithstanding, there are genuine concerns regarding asymptomatic cases.
First, how do we define `symptomatic’? Are `sniffles’ considered symptomatic? Malaise? Is there a specific fever threshold?
And quite frankly, we don’t know what level of symptomology is required for a carrier to be contagious. We’ve seen some evidence to suggest that mildly symptomatic - or even asymptomatic cases - may be able to pass on the virus (see Study: Possible Transmission From Asymptomatic MERS-CoV Case).
While many infections can be traced back to a known risk exposure, for many community acquired cases, no known exposure is ever identified. This at least suggests the virus may be transmitting silently in the community.
From a public relations standpoint, not counting `asymptomatic’ cases may have some advantages. But from a scientific and investigatory standpoint, you need to take all of the available evidence into account, if you hope to understand the full picture.
And perhaps the Saudis truly are.
But we have no way of knowing that since we’ve yet to see the release of their long-promised case control study, they continue to be parsimonious in their release of both research studies and epidemiological data, and their 3-year track record for controlling the virus has been less than enviable.