#18,051While the WHO Epi curve (above) suggests that the threat from MERS-CoV - which first emerged a dozen years ago on the Arabian Peninsula - has declined since the start of the COVID pandemic, various clades of this novel coronavirus continue to circulate in camels - and occasionally spill over into humans - primarily in Saudi Arabia.
Surveillance and reporting of cases has often been lacking in the Middle East (and is nearly non-existent in Africa where the virus can also be found), leading many researchers to believe that a significant number of cases go unreported (see EID Journal: Estimation of Severe MERS Cases in the Middle East, 2012–2016).
Overnight the WHO published a DON update on a cluster of MERS-CoV cases in Riyadh, which began when the index case fell ill in late March. Notably the index case had no known exposures to common `risk factors' (camels, camel products, hospitals, etc.), and was not tested until after he'd been admitted to a hospital for at least two days.
The other two cases were the results of nosocomial transmission of the virus. The index case died a day after admission to the ICU, and as of April 21st, the other two cases were still in the ICU and intubated.
I reproduced some excerpts from the WHO statement below, including their risk assessment. I'll have a bit more after the break.
Middle East respiratory syndrome coronavirus-Kingdom of Saudi Arabia8 May 2024
Situation at a glance
The World Health Organization (WHO) was notified of three human cases, including one death, of Middle East respiratory syndrome coronavirus (MERS-CoV) between 10 and 17 April 2024, by the Ministry of Health of the Kingdom of Saudi Arabia (KSA). All three cases were males from Riyadh aged between 56 and 60 years with underlying health conditions and were not health care workers. The three cases are epidemiologically linked to exposures in a health-care facility in Riyadh, although investigations are ongoing to verify this and understand the route of transmission. Since the beginning of the year, a total of four cases and two deaths have been reported from the Kingdom of Saudi Arabia. The notification of these cases does not change WHO’s overall risk assessment, which remains moderate at both the global and regional levels.
Description of the situation
Between 10 and 17 April 2024, the Ministry of Health (MoH) of the Kingdom of Saudi Arabia (KSA) reported three cases of Middle East respiratory syndrome coronavirus (MERS-CoV), including one death, to WHO. All three cases were reported in Riyadh and linked to the same health-care facility. Two of the cases were identified through contact tracing following identification of the index case. The second and third case are suspected to be secondary health care associated cases due to contact with the index case. The investigations are ongoing to verify this and understand the route of transmission.
The index case is a 56-year-old male school teacher, and a Saudi national residing in Riyadh. On 29 March, he developed a fever, cough, runny nose and body aches. He sought medical care at the emergency room (ER) of a hospital in Riyadh on 4 April, where case number three was also being treated. He was then admitted to a ward on 4 April, where he shared a room with case number two.
On 6 April, he was transferred to Intensive Care Unit (ICU) isolation and intubated, was tested by reverse-transcriptase polymerase chain reaction (RT-PCR), and was confirmed positive for MERS-CoV. The case had underlying health conditions, including hypertension and chronic renal failure requiring hemodialysis . There was no clear history of exposure to typical MERS-CoV risk factors. Close contacts, including 20 health and care workers and seven household members, were followed up, which promptly identified the two secondary cases. Investigations, including determining the source of the infection, are still ongoing. The index case died on 7 April.
The second case is a retired 60-year-old male Saudi national, residing in Riyadh. He was admitted to the ICU at the same hospital in Riyadh on 8 March 2024. On 31 March, he was transferred to a ward, where he subsequently shared a room with the index case on 4 April. The case developed a fever on 6 April and tested positive for MERS-CoV by RT-PCR on 8 April. He has underlying health conditions including heart disease and being a smoker. With no history of exposure to camels, the case is suspected to be a secondary healthcare-associated case due to contact with the index case, with investigations ongoing. The follow-up of 13 health and care workers and one patient has been completed, with no additional cases identified to date.
The third case is a 60-year-old male, retired military personnel and Saudi national, residing in Riyadh. On 4 April, he went to the ER of the same hospital in Riyadh, where the index case was also admitted. He was then admitted to the ward (different to the one that the index case and case number two shared) on 5 April. He developed shortness of breath on 10 April and was transferred to the ICU on 15 April. He tested positive for MERS-CoV by RT-PCR on the same day. He has underlying health conditions including chronic renal failure requiring hemodialysis, malignancy, and liver disease. No history of exposure to camels was identified and, like the second case, he is suspected to be a secondary healthcare-associated case due to contact with the index case. A follow-up of 14 health care workers is ongoing, with no additional cases identified to date.
As of 21 April 2024, the second and third cases remained in the ICU and were intubated on 9 April and 18 April, respectively.
Additionally, since the last Disease Outbreak News (DON) published on 16 February 2024, one further case has been notified through IHR mechanisms with no epidemiological link to the three cases described above. The case is a 32-year-old male with comorbidities from Taif, KSA who had had direct contact with camels, he had onset of symptoms on 21 January and died on 17 February 2024.(SNIP)
WHO risk assessment
The notification of these cases does not change the overall risk assessment. WHO expects that additional cases of MERS-CoV infection will be reported from the Middle East and/or other countries where MERS-CoV is circulating in dromedaries. In addition, cases will continue to be exported to other countries by individuals who were exposed to the virus through contact with dromedaries or their products (for example, consumption of raw camel milk), or in a health-care setting. WHO continues to monitor the epidemiological situation and conducts risk assessments based on the latest available information.
The sharp decline in MERS-CoV cases over the past five years has attributed to a number of factors, including the adoption of pandemic precautions, and potential immunity gained by COVID infection or via the COVID vaccine (see CIDRAP COVID vaccine may boost antibody response to MERS, other coronaviruses).
But since MERS-CoV continues to evolve, and COVID-derived immunity tends to wane over time, it is unknown how long its decline might last.
While mostly theoretical, concerns that MERS-CoV and SARS-CoV-2 might infect a common host and produce a dangerous recombinant have been given serious consideration in scientific journals, including:
Nature: CoV Recombination Potential & The Need For the Development of Pan-CoV Vaccines
Co-infection of MERS-CoV and SARS-CoV-2 in the same host: A silent threat by Buket Baddal
The Recombination Potential between SARS-CoV-2 and MERS-CoV from Cross-Species Spill-over Infections by Abdulrahim A Sajini, Almohanad A Alkayyal & Fathi A Mubaraki
But even without that genetic long-shot, MERS-CoV has long been thought to have at least some pandemic potential (see 2017's A Pandemic Risk Assessment Of MERS-CoV In Saudi Arabia), which is why any new uptick in cases is worthy of our attention.
