#Epidemiology of #MERS-CoV in #Saudi Arabia, 2012–2025: a nationwide surveillance analysis

 

Abstract

Background

Middle East respiratory syndrome (MERS), caused by MERS coronavirus (MERS-CoV), is a severe zoonotic respiratory illness first identified in Saudi Arabia in 2012. Dromedary camels are the recognised reservoir, with human transmission occurring through animal exposure and, less commonly, person-to-person spread, particularly in healthcare settings.

Objective

To characterise all laboratory-confirmed MERS-CoV cases reported in Saudi Arabia from September 2012 to August 2025, examine trends across four periods defined by suspected-case definitions, and identify factors independently associated with mortality.

Methods

We analysed laboratory-confirmed cases in the national surveillance database by period and probable infection source. Case-fatality ratios (CFRs), 95% confidence intervals (CIs), and unadjusted odds ratios were calculated. Multivariable logistic regression assessed independent mortality associations using a prespecified model including period, age, sex, and infection source, and a fuller model additionally considering nationality, comorbidities, and pregnancy. Seasonality of primary cases was assessed using an annual harmonic term.

Results

Among 2,219 cases, 1,545 (70%) were male, 1,566 (71%) Saudi nationals, and 608 (27%) aged ≥65 years. Overall, 1,211 (55%) were primary cases, including 172 (14%) reporting camel contact; 737 (33%) were healthcare-associated and 271 (12%) household- or community-associated. There were 867 deaths (CFR, 39%; 95% CI, 37%–41%). CFR declined from 65% in the earliest period to 32% in the most recent, although changing testing eligibility and ascertainment limit temporal comparisons. Older adults had the highest crude CFR. In the prespecified model, healthcare-associated infection among patients was associated with higher odds of death (aOR, 1.74; 95% CI, 1.15–2.65), while odds were lower among healthcare workers (aOR, 0.09; 95% CI, 0.05–0.17) and household contacts (aOR, 0.29; 95% CI, 0.18–0.48). No consistent seasonality was observed.

Conclusions

MERS-CoV epidemiology in Saudi Arabia reflects persistent zoonotic spillover, episodic healthcare-associated transmission, and substantial mortality, particularly among older adults. Sustained One Health surveillance, rapid detection, and rigorous infection prevention and control remain essential.

Source: 

Link: https://doi.org/10.1093/jtm/taag094

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#MERS #Coronavirus in #Camels, #Kazakhstan, 2025

 

Abstract

In 2025, a respiratory disease outbreak occurred among camels in Kazakhstan. We detected Middle East respiratory syndrome coronavirus by using quantitative reverse transcription PCR in 38 symptomatic camels, demonstrating active circulation in Central Asia. Our findings highlight the need for enhanced surveillance to assess zoonotic transmission risk.

Source: 

Link: https://doi.org/10.3201/eid3211.260394

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#MERS #coronavirus - Kingdom of #Saudi Arabia (#WHO D.O.N., Oct. 16 '26)

 

Situation at a glance

    Between 1 January and 5 October 2026, the Kingdom of Saudi Arabia reported eight laboratory-confirmed cases of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection, including one death. 

    Cases were detected across six locations: Al Jouf (1), Arar (1), Hafr Al-Batin (1), Riyadh (2), Tabuk (1) and Taif (2). 

    No epidemiological links were identified between any of the cases. 

    All eight cases were symptomatic, most commonly presenting with fever (6/8), dyspnea (5/8), and cough (4/8). 

    None were health and care workers. 

    Infection was confirmed by RT-PCR testing. 

    MERS is a zoonotic viral respiratory disease for which dromedary camels serve as the primary animal reservoir and two cases reported direct contact with camels while six reported no known camel exposure. 

    Seven of eight cases had underlying comorbidities, recognized risk factors for severe MERS-CoV disease. 

    The cases appear to represent sporadic infections related to zoonotic spillover rather than a single outbreak cluster.

Description of the situation

    Between 1 January and 5 October 2026, a total of eight cases of MERS-CoV, including one death, was reported from six locations in the Kingdom of Saudi Arabia. 

    Of the eight reported cases, five occurred among persons aged 70 years and older, two among adults aged 50–59 years, and one among an adult aged 30–39 years. 

    Seven cases had underlying comorbidities, two reported direct camel contact, and one death was reported in an older adult (>65 year old) with comorbidities. 

    There was no known epidemiological link identified among cases.

        § Case 1: 

            - A male aged 50–59 years, with comorbidities, from Al Jouf developed symptoms on 14 March 2026. He reported no known contact with camels or camel products. The patient was hospitalized on 17 March and laboratory confirmation of MERS-CoV infection was obtained by RT-PCR on 19 March.

        § Case 2: 

            - A male aged ≥70 years, with comorbidities, from Taif developed symptoms on 18 April 2026. He reported no known contact with camels or camel products. The patient was hospitalized on the same day, and laboratory confirmation was obtained on 22 April. He subsequently died as a result of the illness.

        § Case 3: 

            - A male aged ≥70 years, with comorbidities, from Hafr Al-Batin developed symptoms on 20 May 2026. He reported direct contact with camels. The patient was hospitalized on 26 May and laboratory confirmation was obtained on 27 May.

        § Case 4: 

            - A female aged ≥70 years, with comorbidities, from Riyadh developed symptoms on 31 July 2026. No known exposure to camels or camel products was reported. She was hospitalized on 3 August and laboratory confirmation was obtained on 8 August.

        § Case 5: 

            - A male aged 50–59 years, with comorbidities, from Tabuk developed symptoms on 20 August 2026. He reported no known contact with camels or camel products. He was hospitalized on 23 August and laboratory confirmation was obtained by RT-PCR on 24 August.

        § Case 6: 

            - A male aged 30–39 years, with no known comorbidities, from Riyadh developed symptoms on 14 August 2026. He reported no known contact with camels or camel products. He was hospitalized on 20 August and laboratory confirmation was obtained on 23 August.

        § Case 7: 

            - A male aged ≥70 years, with comorbidities, from Taif developed symptoms on 11 September 2026. He reported no known contact with camels or camel products. He was hospitalized on 17 September and laboratory confirmation was obtained on 19 September.

        § Case 8: 

            - A male aged 60–69 years, with comorbidities, from Arar developed symptoms on 20 September 2026. He reported direct contact with camels. He was hospitalized on 20 September and laboratory confirmation was obtained on 21 September. 

Public health response

    The Kingdom of Saudi Arabia has incorporated MERS-CoV testing into sentinel surveillance algorithms, with testing conducted among patients who test negative for influenza and SARS-CoV-2. This approach aims to improve case detection given the overlapping clinical presentation of MERS, COVID-19, influenza and other respiratory infections. Additionally, IPC practices have improved considerably since 2012, implementing regular training for health and care workers, IPC programmes in health facilities and at national level and improving IPC practices in healthcare settings.

    National health authorities continue to promote public awareness and risk reduction measures, particularly regarding zoonotic transmission from dromedary camels. 

    Recommended measures include regular hand hygiene before and after animal contact, avoiding contact with sick animals, avoiding consumption of raw camel milk, camel urine, and undercooked camel meat, and seeking medical care when respiratory symptoms develop. 

    The Ministry of Health also continues to promote respiratory hygiene measures, including covering coughs and sneezes, avoiding close contact with ill individuals, and maintaining good respiratory hygiene. 

    In parallel, coordination has been established between the Public Health Authority and the National Center for the Prevention and Control of Plant Pests and Animal Diseases. 

    Appropriate control measures have been implemented for involved camels in accordance with animal health recommendations.

    Contact tracing has been conducted for all confirmed cases; no secondary cases have been identified to date. Enhanced infection prevention and control (IPC) measures remain in place at healthcare facilities. Health and care workers who are exposed before patients are isolated or identified as being infectious, were followed up and no secondary cases have been reported in healthcare facilities as a result of these cases.

WHO risk assessment

    MERS is a zoonotic viral respiratory disease caused by MERS-CoV, for which dromedary camels serve as the primary animal reservoir. Human infection can range from asymptomatic or mild illness to severe disease and death. Human infections continue to occur through direct or indirect exposure to infected dromedaries or their products, while limited human-to-human transmission has been documented, primarily among close contacts and in healthcare settings. Sustained community transmission has not been observed. No licensed vaccine for MERS-CoV exists to date.

    As of 5 October 2026, WHO had been notified of 2643 laboratory-confirmed MERS cases globally, including 965 deaths, since the virus was first identified in 2012. 

    The majority of cases (84%; 2232 cases and 870 deaths) have been reported from Saudi Arabia. These figures likely underestimate the true number of infections since mild and asymptomatic cases may remain undetected/unreported, while the reported case fatality of ratio of 37% may overestimate mortality among infections.

    Although the number of reported MERS cases has declined substantially since 2020, MERS-CoV continues to circulate in dromedary camel populations in the Middle East and African regions and continues to cause sporadic human infections. 

    The observed decline in reported MERS cases, in particular during the COVID-19 pandemic emergency phase, is thought to be a result of pandemic-related IPC measures that also limited human-to-human transmission of MERS-CoV, as well as behavioral changes during the pandemic. Any role of potential cross-reactive immunity from SARS-CoV-2 infection and/ or vaccination remains in need of further investigation. Other hypotheses—such as reduced surveillance, viral attenuation, or decreased circulation in camel populations—are not supported by current evidence.

    WHO expects additional sporadic MERS cases to occur in countries where the virus circulates in camels and anticipates that travel-associated exportation of cases will continue. Delays in detection remain possible due to the clinical presentation of MERS being similar with other respiratory infections, including influenza and COVID-19. Numerous outbreaks in KSA and the Republic of Korea have demonstrated that primary cases can result in substantial secondary transmission, particularly in healthcare settings and through importation of travel related cases.

    The notification of the recent cases in Saudi Arabia does not change WHO's overall risk assessment -  the risk remains moderate at both the regional and global levels, reflecting the continued occurrence of sporadic zoonotic infections, the potential for healthcare-associated outbreaks and international exportation of cases, in the absence of sustained human-to-human transmission.

    WHO continues to monitor the epidemiological situation through routine surveillance and reporting under the International Health Regulations (IHR 2005) and conducts ongoing risk assessments using available epidemiological and virological information.

WHO advice

    Based on the current situation and available information, WHO re-emphasizes the importance of maintaining strong surveillance for acute respiratory infections in all Member States. Where warranted by the epidemiological context, MERS-CoV should be included in the testing algorithm and included in differential diagnosis for patients presenting with acute respiratory illness and reporting history of travel to affected areas, and any unusual patterns of respiratory illness or severe acute respiratory infections should be carefully reviewed.

    Human-to-human transmission of MERS-CoV in healthcare settings has been associated with delays in recognizing acute respiratory symptoms of MERS-CoV infection as they are often non-specific and similar to other respiratory illnesses, leading to delayed triage of suspected cases and delayed implementation of IPC measures — both critical to prevent the spread of MERS-CoV in healthcare facilities and if left unmanaged have led to large healthcare outbreaks (example of the Republic of Korea in 2015). 

    Health and care workers should consistently apply standard precautions for all patients at every interaction in healthcare settings. In addition, transmission-based precautions should be implemented when caring for patients with symptoms of acute respiratory infection who are suspected of having a viral infection, including suspected, probable or confirmed MERS-CoV infection. 

    Contact and droplet precautions should be applied, while airborne precautions should be implemented when performing aerosol-generating procedures. Early identification, case management and prompt isolation of cases, contact tracing, together with appropriate IPC measures in healthcare settings and public health awareness, can reduce the risk of human-to-human transmission of MERS-CoV.

    MERS-CoV appears to cause more severe disease in people with underlying chronic medical conditions such as diabetes, renal failure, chronic lung disease and in immunocompromised persons. Therefore, people with these underlying medical conditions should avoid close contact with dromedary camels or their products, particularly when visiting farms, markets, barns or other areas where the virus may be circulating.

    General hygiene measures should be followed when interacting with animals or animal products, including regular hand washing before and after touching animals and avoiding contact with sick animals.

    Appropriate food hygiene should be observed when handling or consuming camel products. People should avoid drinking raw camel milk or camel urine or consuming meat that has not been properly cooked.

    WHO does not advise special screening at points of entry in relation to this event, nor does it currently recommend the application of any travel or trade restrictions. 

(...)

Source: 

Link: https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON618

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Serologic #Testing for #MERS #Coronavirus and #SARS-CoV-2 Cross-Reactive Immune Responses, the #Netherlands

 

Abstract

Cross-reactive SARS-CoV-2–specific antibodies could compromise the specificity of MERS-CoV serology, potentially leading to misclassification of infection history. SARS-CoV-2 exposure induced MERS-CoV antibodies primarily targeting the conserved S2 domain, with occasional neutralizing capacity. Combining MERS-CoV S1 binding with neutralization, however, limited the influence of SARS-CoV-2–induced cross-reactivity on MERS-CoV serology.

Source: 

Link: https://doi.org/10.3201/eid3211.260690

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#Global Genomic #Surveillance of #MERS #Coronavirus

 

Abstract

Middle East respiratory syndrome coronavirus (MERS-CoV) is a persistent zoonotic and epidemic threat. We analyzed 807 publicly available human- and camel-derived MERS-CoV genomes collected during 2012–2024 to assess global genomic surveillance. Most sequences originated from Saudi Arabia and the United Arab Emirates. Major gaps in surveillance persist across Africa and South and Central Asia despite large camel populations, active trade, and evidence of viral circulation. Phylogenetic analysis confirmed predominance of clade B in the Arabian Peninsula and clade C in East Africa, consistent with regional patterns. We identified uneven sampling, incomplete metadata, and long delays between sample collection and public sequence submission, often spanning years. Those limitations reduce the value of genomic data for timely situational awareness. Integrating genomic with population and trade data supports timelier, more representative, and coordinated One Health surveillance for MERS-CoV but reveals major blind spots.

Source: 

Link: https://doi.org/10.3201/eid3211.260668

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#MERS-CoV in #Africa: a One Health #review of the silent #reservoir

 

Summary

Africa harbours more than 80% of the world’s dromedary camels, with a pooled MERS-CoV seroprevalence of 73·7%; however, no autochthonous outbreak in humans has been documented. In this Review, we weigh five interacting explanations for the absence of documented human outbreaks based on the strength of the evidence for each explanation. The primary explanation is virological; many, although not all, African clade C MERS-CoV strains show reduced replication competence in human respiratory tissues, and clade C strains have not become established in Arabian camels or humans despite decades of large-scale export from the Horn of Africa into the world’s most intensively monitored MERS-CoV surveillance system. Environmental contexts, including dry-season herd aggregation, drought, and calving-linked shedding, influence when MERS-CoV exposure occurs in humans. Surveillance limitations, dispersed exposure among the African population particularly pastoralists, lower comorbidity burden than that in affected populations in the Arabian regions, and absent nosocomial amplification are secondary explanations, largely downstream of the primary factors. Although longitudinal cohort studies using enhanced diagnostics detected sporadic spillover in Africa, these infections were asymptomatic. The presence of clade B strains and interclade B×C recombinants in Egyptian camels are surveillance priorities and not evidence of MERS-CoV emergence in humans. Africa’s silent reservoir is therefore not a safe one: continued clade C circulation, alongside emerging clade B introductions and interclade recombinants, could shift this balance, underscoring the need for sustained genomic and human surveillance of the reservoir.

Source: 

Link: https://doi.org/10.1016/j.lanmic.2026.101530

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West African Clade C #MERS-CoV Strains BF785 and Mor213 Induce More Robust #Interferon and Inflammatory Signaling Compared to Clade A in #Human Respiratory Cells

 

Abstract

Clade A Middle East respiratory syndrome coronavirus (MERS-CoV) spilled over from camels into humans in Saudi Arabia in 2012 and caused pneumonia and severe respiratory disease, with a 37% case fatality rate. While clade A and B viruses are closely related phylogenetically, clade B MERS-CoV strains have since outcompeted clade A strains and continue to circulate in camels and humans in the Middle East and cause outbreaks in humans. Clade C strains circulate in camels across the African continent but have not been reported to cause disease in humans. We have shown that a number of East African clade C isolates are less able to utilize the TMPRSS2-mediated pathway for viral entry in both cell lines and primary nasal epithelial cultures, which may underlie the reduced replication of East African clade C strains in humans. However, the reduced replicative capacity of West African strains in human cells appears to be independent of viral entry, suggesting an alternative basis for their attenuation. Here, we report that West African clade C MERS-CoV isolates with deletions in ORF4b encoding a key accessory protein, NS4b, induced significantly more robust interferon and inflammatory responses than clade A MERS in human respiratory cell lines and primary bronchial air–liquid interface cultures. The replication deficit for the West African strain BF785, which has a complete deletion of ORF4b, was partially rescued when RNASEL was knocked out in A549 cells. These findings demonstrate that complete loss of NS4b results in stronger innate immune activation than partial truncation and suggests that differential selection on NS4b may contribute to the varying phenotypes of clade C MERS-CoV strains circulating in African camels.

Source: 

Link: https://www.mdpi.com/1999-4915/18/9/935

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#Risk #assessment of introduction, spread, and zoonotic #spillover of #MERS-CoV Clade B in #camel populations of the Nile Basin and Across #Africa (WHO, summary)

 

INTRODUCTION  

    The Global Early Warning System for Health Threats and Emerging Risks at the Human-Animal Ecosystems Interface (GLEWS+) is a joint initiative of the Food and Agriculture Organization of the UN (FAO), the World Health Organization (WHO), and the World Organisation for Animal Health (WOAH). 

    Within this framework, the GLEWS+ Risk Assessment (RA) mechanism enables the three organizations to jointly assess emerging health threats at the human–animal–ecosystem interface and provide evidence-based risk estimates. 

    These assessments support Members and State Parties in strengthening the prevention, detection, response and control measures.  

Event Description and Scope of the Assessment 

    Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus for which dromedary camels (Camelus dromedarius) are recognized as the primary animal reservoir. 

    Viral circulation within camel populations poses a risk of transmission to humans, particularly in settings characterized by frequent and close human–camel interactions. 

    Historically, MERS-CoV strains detected in dromedary camels in Africa have belonged to clade C, whereas clade B viruses have been associated with the majority of reported human MERS cases and have predominantly circulated in dromedary camel populations in the Middle East. 

    The recent detection of MERS-CoV clade B genome fragments in camels from the Nile Basin region represents a notable epidemiological development, suggesting the possibility of inter-regional viral movement and genetic mixing. 

    This finding may have implications for virus circulation and transmission dynamics, including potential changes in the risk of zoonotic spillover to humans and/or alterations in viral transmissibility and pathogenicity. 

    This assessment evaluates the risk of spread of MERS-CoV clade B within camel populations at both sub-regional (Nile Basin) and regional (Africa) levels. 

    It also assesses the risk of spillover from infected camels to humans in Nile Basin countries. 

    The assessment considers available virological, epidemiological, ecological, and socio-economic factors that influence virus circulation, including camel husbandry practices, pastoralist mobility patterns, cross-border animal movements, live-animal trade networks, and the extent of human-camel contact in the region.  

    Information used in this assessment was compiled from eight countries in Africa reporting camel populations exceeding 10,000 in 2024. 

    The countries included in the assessment are:     

        ° Chad, 

        ° Egypt*, 

        ° Eritrea*, 

        ° Ethiopia*, 

        ° Kenya*, 

        ° Libya, 

        ° South Sudan* and 

        ° Sudan*. 

    The six countries belonging to the Nile Basin sub-region are indicated by an asterisk (*). 

    This risk assessment reflects information available to 27 July 2026. FAO, WHO and WOAH will review and update the assessment as new information becomes available.  

SUMMARY 

    Middle East respiratory syndrome coronavirus (MERS-CoV) is an enveloped, positive-sense RNA virus belonging to the genus Betacoronavirus. 

    It causes Middle East respiratory syndrome (MERS), a zoonotic respiratory disease first recognized in 2012, following the detection of human cases in Saudi Arabia and Jordan. 

    As of 11 June 2026, a total of 2,637 laboratory-confirmed human cases have been reported to WHO globally, the majority from countries in the Arabian Peninsula, with an estimated crude case fatality ratio (CFR) of approximately 37%. (WHO, 2025c) 

    Dromedary camels (Camelus dromedarius) are the primary animal reservoir of MERS-CoV and the main source of zoonotic transmission to humans. 

    Human infections are thought to occur through direct or indirect contact with infected camels. 

    Consumption of raw camel products is considered a plausible route of exposure, although it has not been definitively confirmed as a primary transmission pathway. 

    Human-to-human transmission can occur, particularly in healthcare settings and among those in close-contact. 

    MERS-CoV antibodies have been found in other camelid species, including Bactrian camels, hybrid camels, llamas and alpacas, indicating susceptibility to infection (Islam, 2003). 

    However, these species are not considered to play a significant role in the current epidemiology of MERS.  

    MERS-CoV has evolved into three genetic clades (A, B, and C) with distinct geographic patterns. 

    Clade B predominates in the Arabian Peninsula and has been associated with all recent human infections. 

    Clade A has not been detected since 2015 and is considered extinct. 

    Clade C circulates among dromedary camels across Africa and despite frequent camel imports from Nile Basin countries into the Arabian Peninsula, has not become established in local camel populations. 

    Experimental and phenotypic studies indicate that clade B viruses exhibit higher replication efficiency in human respiratory tissues and experimentally infected camelids, more efficient cellular entry, and prolonged viral shedding compared with clade C viruses. (Rodon, 2023) 

    These characteristics suggest a greater zoonotic potential and an increased likelihood of transmission to humans. (Zhou, 2021) 

    The global camel population is estimated at over 42 million heads as of 2023, with more than 80% of the population in Africa (FAO, 2025a). 

    Camel trade within Africa is predominantly regional and fragmented, with significant informal cross-border movement. (WHO, 2025d, FAO, 2026) In the Nile Basin and the Horn of Africa {1}. 

    Camel trade and movement are largely driven by informal cross-border pastoralist systems, with frequent but poorly documented movements between neighboring countries such as Sudan, Ethiopia, Kenya, and South Sudan. 

    Sudan plays a central role as a major camel exporter, with substantial formal and informal movements to neighboring countries and toward North Africa, while Egypt functions primarily as a terminal hub where camels from multiple origins converge for trade and slaughter. 

    In contrast, long-distance east-to-west transcontinental movement appears limited, with little evidence of sustained camel movement from the Nile Basin into North or West Africa. (Younan et al., 2016) 

    Recent genomic surveillance studies have suggested the introduction of MERS-CoV clade B strains into camel populations in the Nile Basin, outside its historically recognized circulation in the Arabian Peninsula. 

    In Egypt, phylogenetic analyses of a camel-derived sample identified genome fragments clustering with clade B viruses from the Arabian Peninsula, circulating alongside endemic African clade C viruses (Gomaa, Edwards, Wang, Taweel, et al., 2025). 

    Recombination analyses in these studies were interpreted by the authors as suggesting potential genomic mixing between introduced clade B and endemic clade C lineages, highlighting a potential for inter-regional viral exchange and the emergence of novel variants. 

    However, as the publicly available sequences are incomplete, these findings require confirmation through full genome sequencing.  

    In a separate study (Hassan et al., 2025), metagenomic sequencing of nasal swabs from camels imported from Sudan also detected MERS-CoV genome fragments clustering with clade B human and camel strains. 

    Whole genome sequencing would be necessary to confirm these findings and better characterize their evolutionary relationships. 

    Overall, while these observations suggest the possible introduction of clade B viruses into camel population in the Nile Basin sub-region, additional research is required to determine whether there is sustained circulation, establishment, or recombination of clade B viruses in continental African camel populations. 

    Using a qualitative evidence-based approach and considering the assessed likelihood and consequences in the countries assessed, the overall risk at sub-regional level (Nile Basin) of further introduction and spread of MERS-CoV clade B within camel populations is minor. 

    The risk of introduction and spread from camel populations in the Nile Basin to camel populations in neighbouring countries is also assessed as minor. 

    However, if MERS-CoV clade B is introduced and established in camel populations in the Nile Basin countries, the public health risk of spillover from camels to humans exposed to infected camels or their products is assessed as high.  

    The level of confidence in the risk estimates is considered low for the first two questions, reflecting limitations in the quality and completeness of available genomic data, the presence of plausible but unconfirmed transmission pathways, very limited surveillance in camels and humans, and evolving camel trade dynamics that may facilitate virus spread within and beyond the Nile Basin. 

    The level of confidence is considered moderate for the third question. 

    While the clinical presentation and potential consequences of MERS-CoV infection in humans are well documented and observed in previous outbreaks, important uncertainties remain regarding the social, behavioral, and contextual factors that influence the likelihood of camel- to- human spillover in the Nile Basin.  

(...)

{1} Countries in the Horn of Africa are: Djibouti, Eritrea, Ethiopia, and Somalia

Source: 

Link: https://www.who.int/publications/m/item/risk-assessment-of-the-introduction--spread--and-zoonotic-spillover-of-mers-cov-clade-b-in-camel-populations-of-the-nile-basin-and-across-africa

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#Genomic and structural #evidence of #SARS-CoV-2 and #MERS-CoV in migratory #birds

 

Significance

Coronaviruses are regarded as highly important pathogens of birds and mammals. Herein, we obtained three almost full-length severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes and one partial Middle East respiratory syndrome coronavirus (MERS-CoV) genome in the feces of migratory birds based on meta-transcriptome and PCR amplification. We determined the affinities and the complex structures between receptor-binding domain (RBD) of the SARS-CoV-2 viral spike protein and angiotensin-converting enzyme 2 (ACE2) protein of two migratory birds, Tundra and Black swans. Moreover, pseudotyped SARS-CoV-2 variants can enter into HeLa cells expressing ACE2 proteins of these birds. Altogether, our results expand our understanding of migratory birds as potential carrier of both SARS-CoV-2 and MERS-CoV.

Abstract

Migratory birds are the natural reservoir of influenza A virus (IAV), but their role as a carrier of SARS-CoV-2 remains unclear. Here, we report the identification of three almost full-length viral genome sequences of SARS-CoV-2 variants of concern (VOCs) in Tundra swans. These sequences are named hCoV-19/Tundra swan/Jiangxi/IMCAS_M1/2021 (IMCAS_M1), hCoV-19/Tundra swan/Jiangxi /IMCAS_M2/2021 (IMCAS_M2), and hCoV-19/Tundra swan/Jiangxi/IMCAS_M3/2021 (IMCAS_M3). IMCAS_M1 and IMCAS_M3 have the same mutations as the Beta VOC (K417N, E484K, and N501Y) in the receptor-binding domain (RBD) of the viral spike (S) protein, whereas IMCAS_M2 shares the same mutations as the Gamma VOC (K417T, E484K, and N501Y) in the RBD with all three showing their distinct mutations in the genomes. Virus receptor angiotensin-converting enzyme 2 (ACE2) proteins from both Tundra swan (tsACE2) and Black swan (bsACE2) can bind to the RBDs of all three viruses and the Alpha VOC, but not to RBD of the prototype (PT) virus. The polar contacts and hydrophobic interactions revealed by cryo-electron microscopy (cryo-EM) structures of the RBD–ACE2 complex, play key roles in virus–receptor engagement. Furthermore, HeLa cells expressing bsACE2 and tsACE2 proteins could be transduced by pseudotyped SARS-CoV-2 variants (Alpha, Beta, and Gamma) but not PT SARS-CoV-2. In addition, we obtained one partial genome of MERS-CoV named Bar-headed goose/Tibet/IMCAS_M4/2022 (IMCAS_M4) with 20,180 bp (~70.0% coverage). Our findings highlight the importance of migratory birds as potential carrier of both SARS-CoV-2 and MERS-CoV, thereby posing potential threat to public health.

Source: 

Link: https://www.pnas.org/doi/abs/10.1073/pnas.2400023123?af=R

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Evaluation of a proposed #link between the #SARS-CoV-2 #furin #cleavage site and mouse-adapted #MERS-coronavirus MA30

 

Significance

This study formally evaluates a hypothesis that has been advanced by some scientists and public commentators in support of a nonnatural origin of SARS-CoV-2. The hypothesis proposes that the unique polybasic furin cleavage motif of SARS-CoV-2 may be technically or evolutionarily derived from a mouse-adapted laboratory strain of MERS-coronavirus (MA30). While the World Health Organization’s Scientific Advisory Group on the Origins of Novel Pathogens (SAGO) concluded that the available evidence was insufficient to support the proposed link, the underlying scientific rationale for this conclusion has not been published. We systematically assessed the evidence from genomic surveillance and conducted additional experimental studies. Together, these data do not support an evolutionary or genetic relationship.

Abstract

The origin of the polybasic furin cleavage site (FCS) of SARS-CoV-2 remains a central question in debates on the emergence of COVID-19. One hypothesis proposes a genetic relationship between the SARS-CoV-2 S1/S2 motif RRAR and the RRVR sequence found in the mouse-adapted MERS-CoV strain MERS-MA30. Here, we combined large-scale bioinformatic analysis with experimental virology to evaluate this scenario. Analysis of over 17 million SARS-CoV-2 genomes revealed that the S:684V substitution corresponding to RRVR occurred repeatedly but only sporadically, never became phylogenetically basal, and showed limited geographic and temporal spread. Using reverse genetics, we generated SARS-CoV-2 variants encoding RRVR and demonstrated that S:684V consistently reduced viral entry efficiency and competitive fitness in multiple cell systems, including human respiratory epithelial cultures. RRVR variants did not evolve toward RRAR but instead accumulated alternative substitutions. These findings do not support an evolutionary relationship between MERS-MA30 and the SARS-CoV-2 FCS.

Source: 

Link: https://www.pnas.org/doi/abs/10.1073/pnas.2601806123?af=R

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#Assessment of #influenza virus and #coronavirus #tropism, #replication competence and disease severity in ex vivo and in vitro cultures of the #human respiratory tract

ABSTRACT

The emergence of animal influenza viruses circulating in poultry and human populations poses a significant public health threat, yet current risk assessment tools that connect surveillance data to human transmission risk and disease severity are lacking. To address this, we employed a semi-quantitative approach to analyze virus tropism and replication competence, conducting risk assessments of influenza and coronavirus adaptation to human transmission in an ex vivo model, and evaluating virus-induced impairment of alveolar fluid clearance (AFC) in vitro as a correlation of disease severity. Our results showed that seasonal influenza A H1N1, H3N2, influenza B, MERS-CoV, and SARS-CoV exhibited productive viral replication and tissue infection in bronchial tissues, whereas wild bird surveillance isolates such as H5N3 and H7N1 showed minimal replication when compared to pandemic H1N1 and highly pathogenic avian influenza (HPAI) H5N1. Notably, differential lung viral replication and tissue tropism were detected for H5N6 and H9N2. HPAI H5N1, H7N9, MERS-CoV, and SARS-CoV caused more severe AFC impairment than seasonal H1N1, H3N2, and influenza B viruses, correlating with their clinical severity. Overall, these findings revealed an important association between viral tropism and human transmissibility in ex vivo explants, as well as the impairment of AFC in vitro, which aligns with the clinical manifestations of disease severity across different viral strains.

Source: 

Link: https://www.microbiologyresearch.org/content/journal/jgv/10.1099/jgv.0.002281

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#Genomic and structural #evidence of #SARS-CoV-2 and #MERS-CoV in migratory #birds

 

Significance

Coronaviruses are regarded as highly important pathogens of birds and mammals. Herein, we obtained three almost full-length severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genomes and one partial Middle East respiratory syndrome coronavirus (MERS-CoV) genome in the feces of migratory birds based on meta-transcriptome and PCR amplification. We determined the affinities and the complex structures between receptor-binding domain (RBD) of the SARS-CoV-2 viral spike protein and angiotensin-converting enzyme 2 (ACE2) protein of two migratory birds, Tundra and Black swans. Moreover, pseudotyped SARS-CoV-2 variants can enter into HeLa cells expressing ACE2 proteins of these birds. Altogether, our results expand our understanding of migratory birds as potential carrier of both SARS-CoV-2 and MERS-CoV.

Abstract

Migratory birds are the natural reservoir of influenza A virus (IAV), but their role as a carrier of SARS-CoV-2 remains unclear. Here, we report the identification of three almost full-length viral genome sequences of SARS-CoV-2 variants of concern (VOCs) in Tundra swans. These sequences are named hCoV-19/Tundra swan/Jiangxi/IMCAS_M1/2021 (IMCAS_M1), hCoV-19/Tundra swan/Jiangxi /IMCAS_M2/2021 (IMCAS_M2), and hCoV-19/Tundra swan/Jiangxi/IMCAS_M3/2021 (IMCAS_M3). IMCAS_M1 and IMCAS_M3 have the same mutations as the Beta VOC (K417N, E484K, and N501Y) in the receptor-binding domain (RBD) of the viral spike (S) protein, whereas IMCAS_M2 shares the same mutations as the Gamma VOC (K417T, E484K, and N501Y) in the RBD with all three showing their distinct mutations in the genomes. Virus receptor angiotensin-converting enzyme 2 (ACE2) proteins from both Tundra swan (tsACE2) and Black swan (bsACE2) can bind to the RBDs of all three viruses and the Alpha VOC, but not to RBD of the prototype (PT) virus. The polar contacts and hydrophobic interactions revealed by cryo-electron microscopy (cryo-EM) structures of the RBD–ACE2 complex, play key roles in virus–receptor engagement. Furthermore, HeLa cells expressing bsACE2 and tsACE2 proteins could be transduced by pseudotyped SARS-CoV-2 variants (Alpha, Beta, and Gamma) but not PT SARS-CoV-2. In addition, we obtained one partial genome of MERS-CoV named Bar-headed goose/Tibet/IMCAS_M4/2022 (IMCAS_M4) with 20,180 bp (~70.0% coverage). Our findings highlight the importance of migratory birds as potential carrier of both SARS-CoV-2 and MERS-CoV, thereby posing potential threat to public health.

Source: Proceedings of the National Academy of Sciences of the United States of America, https://www.pnas.org/

Link: https://www.pnas.org/doi/10.1073/pnas.2400023123

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Cross-clade #vaccination to overcome #sarbecovirus or #merbecovirus #neutralization gaps

 

Highlights

    • Multiplex sVNT profiles neutralizing antibodies across two zoonotic viral families

    • Pre-pandemic serosurveillance identifies human exposure to ACE2-using MERS-like viruses

    • Pathogen-specific vaccination leaves major neutralization gaps against related viral clades

    • Cross-clade prime-and-boost vaccination elicits broad-spectrum neutralizing antibodies

Summary

The coronavirus disease 2019 (COVID-19) pandemic highlights the importance of identifying high risk pathogens, defining the immunity gaps and developing preemptive vaccination strategies. Here, we establish a high-resolution surrogate virus neutralization test detecting neutralizing antibodies against multiple virus families simultaneously, demonstrating good concordance with traditional assays. Extensive serosurveillance of pre-pandemic sera from different continents reveals low prevalence human exposures to different beta-coronaviruses, and identifies individuals with prior exposure to ACE2-binding MERS-like viruses. Furthermore, COVID-19 vaccination induces significant cross-neutralizing antibodies against clade 1b, 1c, and 3 but not clade 1a sarbecoviruses. Similarly, MERS and Nipah convalescent sera neutralize cognate viruses but have limited cross-neutralization against other related merbecoviruses and henipaviruses that utilize DPP4 and ephrin B2 receptors. Finally, a cross-clade prime-and-boost vaccination strategy using antigenically distinct antigens could induce broadly neutralizing antibodies against related viruses beyond vaccine antigens, supporting broad-spectrum beta coronavirus vaccine development.

Source: 

Link: https://www.cell.com/cell-reports/fulltext/S2211-1247(26)00522-X?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS221112472600522X%3Fshowall%3Dtrue

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Addressing the #zoonotic #threat of #merbecoviruses

 

Abstract

Merbecovirus is a subgenus of betacoronaviruses and exhibits high genetic diversity with a capacity for cross-species transmission. However, beyond Middle East respiratory syndrome coronavirus (MERS-CoV), our knowledge of the ecology and pathogenic potential of these viruses remains limited. Merbecoviruses were once thought to rely exclusively on dipeptidyl peptidase 4 for cell entry, but recent discoveries have revealed that several members can also engage with angiotensin-converting enzyme 2 or aminopeptidase N, expanding their receptor repertoire and potential host range. Here we summarize recent advances in understanding of the receptor usage of merbecoviruses and examine how these insights inform pandemic preparedness and risk assessment. We discuss the development of targeted diagnostics, broad-spectrum antivirals and vaccines, including pan-coronavirus strategies. Together, these advances provide a foundation for predictive surveillance and rational countermeasure design, enabling earlier detection and more effective containment of future merbecovirus spillover events before they escalate into epidemics.

Source: 

Link: https://www.nature.com/articles/s41564-026-02397-1

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#Human #MERS-CoV #research in the #Gulf Cooperation Council Countries: A mapping scoping review of #epidemiology, #clade, and research priority gaps

 

Abstract

Middle East Respiratory Syndrome Coronavirus (MERS-CoV) continues to pose a substantial public health challenge within Gulf Cooperation Council (GCC) countries. This scoping review systematically examines geographic distribution, methodological characteristics, and thematic priorities of published research, while identifying critical evidence gaps. A total of 171 peer-reviewed studies on human MERS-CoV were included, with a marked predominance from Saudi Arabia (88.3%). Research output peaked in 2016 and 2019, followed by a decline coinciding with the COVID-19 pandemic. Cross-sectional designs were most common (43.3%), with widespread reliance on non-probability sampling (95.3%). Epidemiology and surveillance constituted the primary research focus (∼24%), with case fatality rate being the most frequently reported metric (43.9%). Limited genomic investigations were identified, with Clade B representing 71.4% of characterized strains. Overall, the evidence base reflects geographic concentration, methodological heterogeneity, and thematic limitations, underscoring the need for expanded research scope and enhanced regional collaboration.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S1876034126001449?via%3Dihub

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Loss of nsp14-exonuclease activity impairs the #replication, proofreading, fitness, and #pathogenesis of #SARS-CoV-2

 

ABSTRACT

Coronaviruses (CoVs) replicate their RNA genomes with a higher degree of fidelity than other RNA viruses, a mechanism mediated by the proofreading and recombination activities of the exoribonuclease domain of replicase nonstructural protein 14 (nsp14-ExoN). Both murine hepatitis virus (MHV) and SARS-CoV tolerate nsp14-ExoN loss-of-function mutations (ExoN−) (D90A and E92A), but have impaired replication fidelity and pathogenesis; yet identical substitutions in MERS-CoV and SARS-CoV-2 have been reported to be lethal. Here, we report a saturation mutagenesis approach facilitating the recovery and analysis of several constellations of SARS-CoV-2 nsp14 ExoN-inactivating, loss-of-function substitutions, including the canonical D90A and E92A. Biochemical assays with purified WT or ExoN-nsp10-14 fusion proteins confirmed that active site substitutions abolished ExoN activity (ExoN−). SARS-CoV-2 ExoN− viruses exhibited impaired replication, RNA synthesis, and recombination, as well as decreased replication fidelity and loss of fitness in vitro. ExoN− viruses were significantly attenuated for replication in human primary airway epithelial cells and were attenuated for replication and pathogenesis in WT mice, as well as the highly susceptible K18 transgenic mice. In the absence of interferon signaling in vivo, SARS-CoV and SARS-CoV-2 ExoN− viral replication could be partially restored. These results demonstrate that SARS-CoV-2 ExoN− viruses are viable but highly impaired for replication, fitness, and fidelity in vitro, as well as innate immune antagonism and pathogenesis in vivo. Collectively, our results solidify the multiple critical roles of nsp14-ExoN across CoV genera and establish new approaches for rescuing and analyzing loss-of-function substitutions in studies of CoV replication, pathogenesis, and evolution.

Source: 

Link: https://journals.asm.org/doi/10.1128/mbio.00073-26

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Respiratory #infections due to #human common cold #coronaviruses, #SARS-CoV, #MERS-CoV, and SARS-CoV-2: #epidemiology, #pathogenesis, clinical features, diagnostics, therapeutics, and vaccine landscapes

 

Summary

Over the past half-century, perceptions of human coronaviruses have evolved from their initial characterisation as causes of the common cold to recognition of their capacity to trigger severe disease and global epidemics. The emergence of three zoonotic coronaviruses—severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002, Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, and SARS-CoV-2 in 2019, has had profound health, economic, and societal consequences and continues to influence global epidemic-preparedness strategies. All three viruses remain on the WHO Blueprint of priority pathogens for research and development. This Review summarises current knowledge on human coronaviruses, drawing lessons from the past 25 years of epidemic outbreaks. The shared and divergent features of SARS-CoV, MERS-CoV, and SARS-CoV-2, including their origins, evolution, transmission determinants, zoonotic transmission, viral entry pathways, pathogenesis, spectrum of clinical manifestations, long-term sequelae, and case-fatality profiles are highlighted. The full range of clinical manifestations, from asymptomatic or atypical presentations to severe acute respiratory and multisystem disease, are outlined together with risk factors for progression and populations with the greatest susceptibility. Diagnostic approaches, including molecular assays, antigen-based tests, and imaging modalities are described alongside current therapeutics, antiviral strategies, immunomodulators, supportive care principles, and evidence from clinical trials. Advances in diagnostics, vaccines, therapeutics, and infection-control practices are examined together with persistent challenges in early recognition, particularly in resource-limited settings. Strengthening multinational clinical trial capacity, leveraging digital innovations, and embedding One Health approaches are essential to mitigating spillover risks and improving global readiness. We review the latest data, identify gaps and opportunities, and outline forward-looking strategies to anticipate and prepare for the threat of future coronaviruses, and other existing or new respiratory pathogens with epidemic potential. Clinicians and other health-care workers play a central role in detecting and reporting possible lethal coronavirus infection including atypical presentations, enabling rapid, coordinated infection control and management responses.

Source: 

Link: https://www.thelancet.com/journals/lanres/article/PIIS2213-2600(26)00049-4/abstract?rss=yes

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Operational #zoonotic #containment of #MERS #coronavirus in #Saudi Arabia: An implementation-oriented #OneHealth genomic #framework

 

Abstract

Background and Aim: 

Middle East respiratory syndrome coronavirus (MERS-CoV) remains a persistent zoonotic threat more than a decade after its first detection, with Saudi Arabia continuing to be the global epicenter of human infections and the main reservoir interface through dromedary camels. Despite ongoing surveillance, advances in molecular diagnostics, and research on vaccines and therapeutics, sporadic zoonotic spillovers and healthcare-associated outbreaks still occur, showing that current prevention strategies are still not enough. This review compiles current evidence from epidemiological studies, camel reservoir research, genomic monitoring, and public health reports published between 2012 and April 2025 to identify the key gaps preventing effective containment. Special focus is given to recent genomic discoveries, including post-2022 clade B sublineages, recombination events, and spike protein changes that might affect transmission and the effectiveness of countermeasures. Available data suggest that MERS-CoV epidemiology is driven by repeated camel-to-human transmission, followed by occasional amplification in healthcare settings rather than sustained community spread. High seroprevalence and frequent detection of viral RNA in juvenile camels, seasonal gathering in markets, and extensive animal movement networks contribute to ongoing viral circulation at the animal–human interface. Genomic studies consistently show close phylogenetic relationships between camel and human isolates, confirming recurrent zoonotic transmissions. However, fragmented surveillance systems, delayed genomic data integration, inconsistent biosecurity practices, and limited field evidence for camel vaccination pose major barriers to control. Additionally, hospital outbreaks continue to occur due to delayed diagnosis, overcrowding, and incomplete adherence to infection-prevention protocols, underscoring the need for improved clinical preparedness. Based on the integrated synthesis of epidemiological, veterinary, and genomic evidence, this review proposes an implementation-focused One Health genomic framework tailored to the Saudi context. The proposed roadmap highlights real-time connection of human and camel surveillance, expands genomic sequencing capacity, targets vaccination strategies in camels and high-risk human populations, standardizes biosecurity measures in markets and abattoirs, and strengthens infection control systems in healthcare facilities. Alignment with national governance structures and Saudi Vision 2030 offers a practical pathway for coordinated multi-sectoral action. This review concludes that MERS-CoV is unlikely to be eradicated soon, but it can be effectively managed through a genomics-enabled, operational One Health approach that combines surveillance, vaccination, clinical preparedness, and policy coordination. The model outlined here provides a scalable way to reduce zoonotic spillover risk and strengthen readiness against future coronavirus and emerging zoonotic threats. 

Source: 

Link: https://veterinaryworld.org/Vol.19/March-2026/29.php

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A natural five-amino-acid insert at the S2’ #cleavage site of #MERS-CoV #spike enhances viral membrane fusion

 

Highlights

• A novel 5-aa insert, TSGVF, is present at the S2’ cleavage site of the spike protein of MERS-CoV from dromedary camels.

• Pseudovirus-based entry assays showed that the TSGVF insert increases viral entry efficiency in different human cells.

• Pseudovirus with TSGVF insert at the S2’ cleavage site showed strong resistance to TMPRSS2 inhibitor.

• The natural occurrence of TSGVF insert at the spike S2’ cleavage site enhances viral membrane fusion and syncytia formation.

Source: 

Link: https://www.sciencedirect.com/science/article/pii/S1995820X26000611?via%3Dihub

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