Saudi MOH Reports 2nd Primary MERS Case In 3 Days In Unayzah

Credit Wikipedia

#14,488


The Saudi MOH has added their 1st MERS case of Epi Week 44 (M,43) and added a second case (apparently belatedly on Sunday) to their Epi Week 43 list (M,10).  Both cases hail from Unayzah (aka`Onaizah' or `Onizah'), and both are listed as `primary'.

Primary cases are those that occur in the community, with no known contact with an infected person, and since many have no recent camel contact, often we have no clue as to how they were exposed.

While not unheard of, MERS infections (particularly `primary cases') reported among children or adolescents are exceedingly rare (see chart below). 

Credit WHO EMRO

Today's case is the 11th so far for the month of October, which represents nearly a tripling of cases over what was reported in September (n=4).

Questions remain, however, over just how sensitive the Saudi surveillance system really is.

Between asymptomatic or mild cases, atypical presentations, and less than 100% reliable laboratory testing (see EID Journal: Sensitivity and Specificity Of MERS-CoV Antibody Testing), it has long been assumed we are only hearing about some fraction of the number of actual infections.

• In November of 2013, we looked at a study published in The Lancet Infectious Diseases, that estimated for every case identified, there are likely 5 to 10 that go undetected. 
• In 2015, when Saudi Arabia had recorded fewer than 1200 MERS cases, a seroprevalence study (see Presence of Middle East respiratory syndrome coronavirus antibodies in Saudi Arabia: a nationwide, cross-sectional, serological study by Drosten & Memish et al.,) suggested nearly 45,000 might have been infected.  
• A 2016 study (see EID Journal: Estimation of Severe MERS Cases in the Middle East, 2012–2016) suggested that as much as 60% of severe Saudi MERS cases go undiagnosed. 
• Just over a year ago, in Evaluation of a Visual Triage for the Screening of MERS-CoV Patients, we looked at a study of the Saudi MERS triage system - to decide who to isolate and test as a potential  case - that found it severely lacking. 

While MERS-CoV activity is down compared to 3 or 4 years ago - primarily due to better infection control in Saudi Hospitals - we've seen studies (see A Pandemic Risk Assessment Of MERS-CoV In Saudi Arabia) suggesting the virus doesn't have all that far to evolve before it could pose a genuine global threat.

So we watch upticks like we're seeing this month closely, for any signs that the virus is getting its act together.