While reports from Riyadh's June hospital cluster have slowed the past few days we continue to see sporadic `primary' MERS cases popping up around the country.
`Primary cases’ are those that occur in the community when there is no known exposure to a healthcare facility or to a known human case.
Some primary cases may linked to either direct or indirect camel exposure. Over the past 3 years, roughly 45% of Saudi cases are listed as either `primary’ or as from an undetermined origin.
Today's case - from the capital city Riyadh - is a primary case in a 67 y.o. male, listed in stable condition, with no known risk exposure.
Over the past 3 weeks Saudi Arabia has reported 47 MERS cases, roughly 2/3rds of whom are linked to the King Khalid University Hospital (KKUH) outbreak (see Saudi MOH On KKUH MERS Outbreak & Increased Asymptomatic Detections).
The remainder are community acquired, many without a clear exposure risk.
Like most viral infections, MERS-CoV can produce a wide range of symptoms, and as we've seen recently, many can carry and shed the virus with little sign of illness.
While the source of many community acquired cases remains unknown, asymptomatic carriage and transmission offers one plausible - if not yet proven - explanation (see Study: Possible Transmission From Asymptomatic MERS-CoV Case).