With roughly 3 million religious pilgrims partaking in the Hajj this weekend in Saudi Arabia - and many of those international visitors - for the fourth year in a row health officials around the globe are on alert for the possibility of seeing MERS infections among returning Hajjis.
While the potential is certainly there (see WHO: Mass Gatherings & MERS), so far, the Hajj has not turned out to be a serious factor in the dissemination of MERS-CoV.
But the MERS virus continues to evolve (see Epidemiology of a Novel Recombinant MERS-CoV in Humans in Saudi Arabia), and with it so potentially does the threat. This new clade - first identified in a patient 18 months ago and dubbed NRC-2015 - has quickly become the dominant strain in Saudi Arabia in both humans and camels.
During this same time period we've also seen some subtle changes in patient profiles, including a substantial jump in the number of asymptomatic cases (possibly due to better testing and surveillance), and a marked increase in cases attributed to `indirect camel contact'.
Whether these shifting patterns are due to a change in the virus, or to changes in KSA's surveillance and reporting, is unknown.
Trying to find out, researchers investigated 27 community acquired cases reported over a 2-month timespan from earlier this year, and found the NRC-2015 clade still king of the hill, and that half of the cases did not have the traditional risk exposures (camels, hospital or household exposure to known cases) for MERS acquisition.
But they noted: Among the remaining 12 case-patients without these risk factors, 7 were identified as having at least some exposure to persons with direct camel contact.
Whether this indicates asymptomatic transmission of the virus, or transfer of infectious materials via fomites, or some other mechanism of virus transfer is unknown. The authors do say:
Our findings suggest that community and household exposure to persons with direct camel contact might play a role in MERS-CoV acquisition. Further investigation is needed to determine any specific roles of these interactions in MERS-CoV transmission.
Follow the link below to read the full letter.
Exposures among MERS Case-Patients, Saudi Arabia, January–February 2016
To the Editor: Risk factors for primary acquisition of Middle East respiratory syndrome (MERS) coronavirus (CoV) include recent direct contact with dromedary camels (1), but secondary transmission, associated with healthcare settings (2–4) or household contact (5), accounts for most reported cases.
Because persons with MERS often do not report any of these risk factors, we investigated MERS cases in Saudi Arabia during an apparent period of limited hospital transmission. Through telephone interviews of case-patients and information from routine investigations, we aimed to characterize exposures and to explore additional factors potentially important in disease transmission. We also genetically sequenced MERS-CoV from respiratory specimens to identify circulating strains.
For confirmed MERS cases (6) reported in Saudi Arabia during January–February 2016, we assessed exposures during the 2 weeks before illness onset (exposure period), including direct (1) and indirect camel contact; indirect contact was defined as 1) having visited settings where camels were kept but without having direct contact or 2) exposure to friends or household members who themselves had direct camel exposure (1). We assessed whether case-patients had worked at, visited, or been admitted to a healthcare setting or had contact with a person known to have MERS during the case-patient’s exposure period. We also asked about recent travel and if any household members were healthcare personnel. For persons too ill to participate or deceased, we interviewed relatives or close friends.
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Raafat F. Alhakeem, Claire M. MidgleyComments to Author , Abdullah M. Assiri, Mohammed Alessa, Hassan Al Hawaj, Abdulaziz Bin Saeed, Malak M. Almasri, Xiaoyan Lu, Glen R. Abedi, Osman Abdalla, Mutaz Mohammed, Homoud S. Algarni, Hail M. Al-Abdely, Ali Abraheem Alsharef, Randa Nooh, Dean D. Erdman, Susan I. Gerber, and John T. Watson