Friday, September 20, 2013

Eighteen More MERS Cases; 'Silent' Carriers Confirmed

Middle East Respiratory Syndrome Corona Virus
The World Health Organization has confirmed the MERS virus in eighteen more patients including three deaths in hard hit Saudi Arabia. The newest victims range in age from three to 75 years. This brings the total of WHO laboratory confirmed cases to 132 including 58 fatalities.

This latest report was followed by an announcement that scientists from the UK and Saudi Arabia had completed analysis of the genome of the MERS virus.

Researchers believe the virus has passed between animals and humans perhaps several times in addition to being transmitted among humans. According to lead author Professor Paul Kellam, “Our findings suggest that different lineages of the virus have originated from the virus jumping across to humans from an animal source a number of times.” The animal source is still unknown and tests of wild and domestic animals is ongoing.

According to Professor Memish, “Further studies need to be carried out. The animal source of MERS-CoV and the way that it is transmitted to humans is not yet known...This is critical for developing interventions for reducing the risk of transmission, defining the epidemiology and developing effective control measures.”

The study cautions that some of the infected showed no symptoms but are capable of acting as a 'carrier' and spreading the virus to others. This raises the possibility that there could be considerably more un-diagnosed infections than officially reported. The questions over confirmed numbers are exemplified in this report from Infection Control Today showing the MERS cluster in Italy has been re-classified as 'probable' from 'confirmed' because the samples were not collected per current WHO standards:
"A "probable" designation by WHO criteria refers to patients who are considered to have a high likelihood of having been infected with MERS-CoV, but from whom adequate samples could not be obtained for complete testing according to the current criteria established for laboratory confirmation."
This cluster involved a two year old and 42 year old who became ill after close contact with a man who had recently returned from Jordan. According to WHO, this raises the number of  probable MERS infections to seventeen. (See 'Progression of Italian MERS Cluster Described', Aug 23, 2013). 

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