Monday, November 25, 2013

Referral: Dr. Mackay On MERS-CoV, Asymptomatic Infections, And Viral Shedding


Coronavirus – Credit CDC PHIL



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One of the many unknowns about the MERS coronavirus (and indeed, many other viruses) is how many asymptomatic cases there really are, and whether these cases shed enough virus to be contagious.  With sporadic community cases popping up  the virus must be either quietly circulating, or in the environment somewhere.


In August we learned of a man who, while hospitalized in a Saudi facility that reported no other MERS infections, fell ill with the virus 14 days after admission. Given the believed incubation period of < 14 days, this suggests he may have acquired the virus from contact with an asymptomatic carrier inside the hospital (see  Study: Possible Transmission From Asymptomatic MERS-CoV Case).


We know that influenza patients can be infectious for up to 24 hours before they display overt symptoms, and some studies suggest that asymptomatic carriers carry a viral load similar to those with symptoms (see PLoS One: Influenza Viral Shedding & Asymptomatic Infections). But how well asymptomatic influenza carriers actually spread the virus remains a topic of considerable debate (see Public Health Report Does Influenza Transmission Occur from Asymptomatic Infection or Prior to Symptom Onset?). 


This morning Dr. Ian Mackay takes us on a tour of virus testing (PCR, viral culture, and serology) done for SARS a decade ago, and explains how those results might (or might not) apply to the MERS coronavirus.  Follow the link below to read:



No symptoms but still shedding virus?

Monday, 25 November 2013

One of the many questions that remain unresolved for MERS-CoV is whether a human who is PCR-positive for the virus, but does not show signs or symptoms of being sick, can spread that infection on to other humans - or animals for that matter.

(Continue . . . )


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