Ten days ago (see WHO: UAE & Saudi MERS Updates) we learned of the UAE’s 5th MERS case of 2015, who was described as:
A 65-year-old, non-national male from the Eastern region developed symptoms on 31 May and was admitted to hospital on 6 June. The patient, who has comorbidities, tested positive for MERS-CoV on 14 June. He has no history of exposure to known risk factors in the 14 days prior to onset of symptoms.
Although he was described as being in critical condition, on June 18th we learned that he had died (see UAE: Abu Dhabi Announces MERS Fatality, 1 Additional Case?), along with a nearly blind reference to another case.
Today the World Health Organization has posted a DON with details on two family contacts of this fatal case – both who tested positive for MERS – and both who have remained asymptomatic while in isolation. First the WHO report, then I’ll return with a bit more:
Disease outbreak news
26 June 2015
On 21 June 2015, the National IHR Focal Point of the United Arab Emirates notified WHO of 2 additional cases of Middle East respiratory syndrome coronavirus (MERS-CoV) infection.
Details of the cases are as follows:
- A 46-year-old, non-national female from the Eastern region was identified through contact screening as she is a family member of a laboratory-confirmed MERS-CoV case reported in a previous DON on 16 June. The patient, who has comorbidities, tested positive for MERS-CoV on 18 June. She has no history of exposure to other known risk factors in the 14 days prior to detection. Currently, she is still asymptomatic in a negative pressure isolation room on a ward.
- An 11-year-old, non-national male from the Eastern region was identified through contact screening as he is a family member of a laboratory-confirmed MERS-CoV case reported in a previous DON on 16 June. The patient, who has no comorbidities, tested positive for MERS-CoV on 18 June. He has no history of exposure to other known risk factors in the 14 days prior to detection. Currently, the patient is asymptomatic in a negative pressure isolation room on a ward.
Contact tracing of household and healthcare contacts is ongoing for these cases.
The National IHR Focal Point of the United Arab Emirates also notified WHO of the death of the MERS-CoV case that was reported in a previous DON on 16 June.
Globally, WHO has been notified of 1,350 laboratory-confirmed cases of infection with MERS-CoV, including at least 480 related deaths.
MERS, like many viral infections, is capable of producing a broad spectrum of illness – ranging from mild (or even asymptomatic) to severe and life threatening. Older patients, and those with co-morbidities, tend to do worse with the virus than younger, healthier individuals, although we’ve seen serious morbidity among all cohorts.
Among the unknowns is how many people have actually been infected. The `official’ number of 1350, is likely a serious undercount, as we normally only hear about the `sickest of the sick’ who are hospitalized and tested.
Contact tracing has unveiled that a percentage of infections are either asymptomatic, or so mild as not to provoke enough concern for the patient to seek medical assistance. Among known cases, that number is running 10%-20%, but their discovery is more serendipitous than the result of broad-based testing.
How many there really are, is unknown.
We’ve seen estimates, from a variety of sources. In November of 2013, we looked at a study published in The Lancet that calculated for every case identified, there were likely 5 to 10 that went undetected.
A more recent study, also published in the Lancet, projected 44 951 (95% CI 26 971–71 922) individuals older than 15 years might be seropositive for MERS-CoV in Saudi Arabia.
Although it seems likely that asymptomatic (or mildly symptomatic) cases are less infectious than patients with full blown symptoms - they still shed the virus - and so the possibility exists that they might serve as silent vectors of the disease in the community (see Study: Possible Transmission From Asymptomatic MERS-CoV Case).
Unfortunately, after nearly 2 years of waiting we still don’t have a comprehensive case-control study from the Saudis.
Which means that many aspects of how this virus spreads in the community remain largely unanswered.