Most Recent WHO EMRO Update on MERS-CoV
#18,300
When SARS-CoV-2 emerged in 2019 - sparking the first known coronavirus pandemic - we were actively following several other coronaviruses with pandemic potential, particularly MERS-CoV; which emerged from camels in 2012, and had infected > 2400 people in the previous 8 years.
While not nearly as transmissible as SARS-CoV-2, MERS-CoV appears to be much deadlier than COVID (35% CFR among known cases), although surveillance and reporting has been limited.
In 2017 we saw a study (see A Pandemic Risk Assessment Of MERS-CoV In Saudi Arabia) suggesting the virus didn't have all that far to evolve before it could pose a genuine global threat.
Since COVID emerged, reporting of MERS cases by Middle Eastern nations - which has often left a lot to be desired - has plummeted (see WHO EMRO Chart above). In their April 2022 update, the WHO suggested that MERS cases are probably still occurring, but going unreported due to the pandemic.Admittedly, detecting MERS cases isn't always easy. Over the past decade we've looked at many of the challenges of MERS-CoV surveillance, including:
EID Journal: Sensitivity and Specificity Of MERS-CoV Antibody TestingEven before the COVID pandemic, we'd seen estimates that the vast majority of MERS cases go undiagnosed (or unreported) in the Middle East (see EID Journal: Estimation of Severe MERS Cases in the Middle East, 2012–2016).
AJIC:Intermittent Positive Testing For MERS-CoV
JIDC: Atypical Presentation Of MERS-CoV In A Lebanese Patient
Evaluation of a Visual Triage for the Screening of MERS-CoV Patients
So, while it doesn't get the media attention it once did, we continue to keep an eye on this continually evolving coronavirus threat (see last May's WHO DON on MERS-COV Cluster In Saudi Arabia).
Last June, in Cureus: Circulation of Non-(MERS) Coronaviruses in Imported Camels in Saudi Arabia, we looked at a study which found a diverse array of coronaviruses with zoonotic potential in imported camels. The authors wrote:
This suggests that camel importation could introduce new, divergent CoVs into Saudi Arabia, potentially leading to recombination events and increased viral diversity.
All of which brings us to a new preprint which finds that the MERS-CoV virus continues to evolve, and diversify, in the camel population in Saudi Arabia, and that newer MERS sequences `. . . harbor unique genetic features, including novel amino acid polymorphisms in the Spike protein.'
They also report finding 229E-related human coronaviruses (which cause the `common cold'), co-circulating in dromedaries.
While this is a preprint, it has an impressive pedigree, including Ahmed M Hassan, Ziad Memish, and Christian Drosten, among others. Due to its length, I've only posted the abstract and some excerpts from the discussion. Follow the link to read it in its entirety. I'll have a brief postscript after the break.
Ongoing evolution of Middle East Respiratory Syndrome Coronavirus, Kingdom of Saudi Arabia, 2023-2024Ahmed M Hassan, Barbara Mühlemann, Tagreed L Al-Subhi, Jordi Rodon, Sherif A El-Kafrawy, Ziad Memish, Julia Melchert, Tobias Bleicker, Tiina Mauno, Stanley Perlman, Alimuddin Zumla, Terry C Jones, Marcel A Müller, VVictor M Corman, Christian Drosten, Esam I Azhar
doi: https://doi.org/10.1101/2024.09.12.612455
AbstractD) Spatial distribution of sub-lineages within the B5-2023 clade.
Middle East respiratory syndrome coronavirus (MERS-CoV) circulates in dromedary camels in the Arabian Peninsula and occasionally causes spillover infections in humans. Due to lack of sampling during the SARS-CoV-2 pandemic, current MERS-CoV diversity is poorly understood.Of 558 dromedary camel nasal swabs from Saudi Arabia, sampled November 2023 to January 2024, 39% were positive for MERS-CoV RNA by RT-PCR. We generated 42 MERS-CoV and seven human 229E-related CoV by high-throughput sequencing. For both viruses, the sequences fell into monophyletic clades apical to the most recent available genomes.The MERS-CoV sequences were most similar to those from lineage B5. The new MERS-CoVs sequences harbor unique genetic features, including novel amino acid polymorphisms in the Spike protein. The new variant. Med. Virology: Potential Cross-Species Transmission Risks of Emerging Swine Enteric Coronavirus to Human Beingss require further phenotypic characterization to understand their impact. Ongoing MERS-CoV spillovers into humans pose significant public health concerns, emphasizing the need for continued surveillance and phenotypic studies.
(SNIP)
Forty-three percent of the 51 sequenced samples showed evidence of infection with HCoV169 229E-related CoV. Widespread infection of dromedary camels with that virus, both with and without MERS-CoV co-infection, has been observed previously.26,27 170 The apical placement of the newly described HCoV-229E-related sequences, together with temporal signal observed here, may also point to a ladder-like pattern of evolution of the virus in dromedary camels.
Similarities in the epidemiology of HCoV-229E-related CoV and MERS-CoV in dromedary camels, including the absence of severe disease and the higher rate of infection in younger camels,27 175 suggest that HCoV-229E-related CoV may be maintained at population level in a similar fashion as MERS-CoV, highlighting the importance of dromedary camels as reservoir hosts for coronaviruses.
Ongoing spillovers of MERS-CoV into the human population in the Arabian Peninsula pose a significant public health concern. Global efforts to mitigate MERS-CoV impact in human populations are threatened by lineage B5 viruses, which possess enhanced replicative fitness and transmission capabilities in dromedary camels.21–24 181The MERS-CoV genome evolution revealed by the sequences presented here, the first available from the Arabian Peninsula since 2019, highlight the urgent need for further MERS-CoV surveillance and phenotypic studies
MERS-CoV isn't the only non-COVID coronavirus that we are watching. A few recent blogs include:
Preprint: Human Cell adaptation of the Swine Acute Diarrhea Syndrome Coronavirus Spike Protein
J. Med. Virology: Potential Cross-Species Transmission Risks of Emerging Swine Enteric Coronavirus to Human Beings
Nature: Comparative Susceptibility of SARS-CoV-2, SARS-CoV, and MERS-CoV Across Mammals