Eleven days ago the Saudi MOH announced the first of what has now grown to be 7 MERS cases linked to a household of 36 female expat workers, all living together in a 3 room apartment in Riyadh. According to the MOH, these women worked for a private contractor providing janitorial services to Princess Nora University, and no students are involved.
The `Probable Source Of Infection’ was listed as `under review’ for the first two cases, as `household contact’ for the second two, and as `secondary household contact’ for the three latest cases.
It is not clear what differentiates the last three cases from the others - or how the virus was initially introduced into this household - but hopefully a WHO update will clarify matters. The first six cases have all been described as symptomatic, but stable.
Today, the MOH announces an `asymptomatic’ case , involving a 52 year old member of the household.
`Asymptomatic’ can be a subjective term, as it depends on ones threshold for counting symptoms, but very mild or `asymptomatic’ MERS infections appear to be fairly common. How common? We really don’t know, since until recently the Saudi MOH hasn’t considered RT-PCR positive – but asymptomatic – cases, as real `cases’.
In September’s WHO Statement On The 10th Meeting Of the IHR Emergency Committee On MERS, the Committee noted that `Asymptomatic cases that have tested positive for the virus are not always being reported as required’
As discussed previously, there are serious questions over how one defines `symptomatic’. Are `sniffles’ considered symptomatic? Malaise? Is there a specific fever threshold? Are non-respiratory symptoms (gastrointestinal) counted?
All of this is important, as we don’t currently 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), but the actual risks of transmission are still unknown.
Hopefully today’s announcement is an indication that the Saudi MOH is now giving asymptomatic cases the attention they deserve - and that they are using this large household cluster to aggressively investigate all aspects of the transmission of this virus.
One further hopes they will share what they find.