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Commentary
Mild UAE HCW
MERS
Cluster Raises Pandemic Concerns
Recombinomics
Commentary 19:30
July 18, 2013
The above comments from the latest WHO MERS coronavirus update describe two more hospitals involved in onward MERS-CoV transmission. The index case (82M) was the first case identified by the United Arab Emirates, and the above cases bring the total number identified by the UAE (see map) to 5, which is in addition to the case (65M) exported to France or the case (73M) treated in Germany.
The above four confirmed cases in health care workers (HCWs) follows a report of two mild Asir cases in the Kingdom of Saudi Arabia (KSA) described yesterday and confirmed by WHO today. That cluster was in Asir and also involved a HCW, which extends a trend in onward transmission throughout KSA involving mild cases (family contacts and/or HCWs). These milder cases have a case fatality rate of zero, because many are not hospitalized, while others are briefly hospitalized until, they test negative for MERS-CoV. These cases do not develop pneumonia and are not treated.
These mild cases were initially noted by KSA officials who commented in the spring that MERS-CoV was producing flu like symptoms in cases that did not require hospitalization of treatment. Since these officials noted that most of the mild cases were in Jeddah, when no mild cases had been confirmed, the comments strongly suggested that KSA was identifying and monitoring these cases using lab results that fell shy of the WHO definition of a confirmed case. Although it was unclear if these cases were just below the official cut-off, or were not confirmed in subsequent test due to sample degradation, or more stringent testing requirements, It was clear that the cases were being lab confirmed because mild cases would share symptoms with a wide variety of respiratory infections (and these cases were not "seemingly sporadic").
When the CDC identified (via MERS-CoV antibodies) mild and asymptomatic cases in the Jordan ICU outbreak and Italy identified asymptomatic cases via aggressive PCR testing, KSA followed suit by citing mild and asymptomatic contacts of confirmed cases. Although WHO initially described these cases as “weak positives” these cases were included in the confirmed cases category, dramatically lowering the case fatality rate (CFR).
This lower CFR in previously healthy contacts (family members or HCWs) was also seen in onward transmission cases in England, Tunisia, and Italy, indicating MERS-CoV was transmitting in sustained manner by the milder cases not linked to severe hospitalized index cases. There is no ongoing surveillance for these milder cases. The mild and asymptomatic reported above are cases linked to severe cases which are identified in surveillance of hospitalized cases.
In WHO’s recent press conference, they denied knowledge of the number or significance of the mild and asymptomatic cases, and have no plans to acknowledge the sustained community transmission of MERS-CoV.
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