@WHO announcement today on Twitter
# 7420
The World Health Organization has a new Global Alert & Response update on MERS-CoV situation, adding four cases to the tally, and providing us with a previously undisclosed detail; that two of the healthcare workers infected in Taif are reportedly asymptomatic.
First the update, then I’ll be back with a little more.
Middle East respiratory syndrome coronavirus (MERS-CoV) - update 22 June 2013
22/06/2013
The Ministry of Health in Saudi Arabia has announced an additional four laboratory-confirmed cases with Middle East respiratory syndrome coronavirus (MERS-CoV).
The first case is a 43 year-old female in the Eastern Region who has recovered. The other three cases are female health care workers aged 29, 39 and 45 from Taif governorate who cared for two previously confirmed MERS-CoV cases and were detected as part of the outbreak investigation and contact tracing. Two of these three cases were asymptomatic and all three tested weakly positive by PCR.
Globally, from September 2012 to date, WHO has been informed of a total of 68 laboratory-confirmed cases of infection with MERS-CoV, including 38 deaths.
WHO has received reports of laboratory-confirmed case originating in the following countries in the Middle East to date: Jordan, Qatar, Saudi Arabia, and the United Arab Emirates (UAE). France, Germany, Italy, Tunisia and the United Kingdom also reported laboratory-confirmed cases; they were either transferred there for care of the disease or returned from the Middle East and subsequently became ill. In France, Italy, Tunisia and the United Kingdom, there has been limited local transmission among patients who had not been to the Middle East but had been in close contact with the laboratory-confirmed or probable cases.
This latest update does not include the two cases announced overnight by the Saudi MOH (see MERS-CoV: KSA Reports 2 New Cases, 1 Fatality).
The big news here is the detection of asymptomatic infections in two healthcare workers, with their tests described as being `weakly positive’ by PCR.
While most of the earlier MERS-CoV cases we’ve seen have presented with serious illness, a minority have displayed only mild symptoms.
Earlier this week the possibility of subclinical MERS-CoV infection was raised when we learned one of the seropositive cases from the Jordanian hospital outbreak a year ago reported not remembering having been ill during that time (see MERS-CoV: Early Serological Results).
Today’s announcement appears to be our first contemporaneous lab report/medical observation that confirms asymptomatic carriage of the virus.
As we discussed earlier this week, asymptomatic infections can be found with nearly every virus. How a disease presents in its host depends greatly on the competence of their immune system, previous exposures, age, and other comorbidities.
So while firm evidence has been lacking until now, it is not terribly surprising to now find asymptomatic cases of MERS-CoV.
Whether asymptomatic MERS cases can go on to infect others is an important question that we don’t know the answer to, yet.
Confirmed asymptomatic carriage of the virus will likely encourage more aggressive testing - particularly among contacts of known cases - whether they are currently symptomatic or not.
Dr. Ian Mackay shared his thoughts earlier this week on the need for expanded testing with this virus in MERS-CoV in the Asymptomatic? on his Virology Down Under Blog.
You’ll have to scroll down the page a bit to get to last Tuesday’s entry.
