In May 2024 WHO issued a Disease Outbreak News (DON) update stating that it has been notified of three human cases, including one death, of Middle East respiratory syndrome coronavirus (MERS-CoV). These cases were reported between 10th and 17th April 2024 by the Ministry of Health of the Kingdom of Saudia Arabia. Although investigations are “ongoing” to verify the link and route of transmission for the cases, WHO’s overall risk assessment remains “moderate” at both global and regional levels.
What is MERS?
Middle East respiratory syndrome (MERS) is a viral respiratory infection caused by MERS-CoV, with an estimated mortality rate of 36%. However, WHO suggests that this may be an overestimate as the case fatality ration (CFR) is based on laboratory-confirmed cases. The natural host and zoonotic source of the virus is the dromedary camel. Humans are infected from direct or indirect contact with these camels, but the virus has also demonstrated the ability to transmit between humans, mostly in health care settings. MERS disease can be asymptomatic or present mild respiratory symptoms, but it can also cause severe acute respiratory disease and death.
There is no approved vaccine or specific treatment, but there are several MERS-CoV-specific vaccines and therapeutics in development.
The first case
All three cases reported to WHO were identified in Riyadh and linked to the same health-care facility. Two cases were identified through contact tracing, initiated after the identification of the index case. These cases are “suspected to be secondary health care associated cases” from contact with the index case. However, investigations are underway to determine the route of transmission.
The index case is a 56-year-old male, a teacher who lived in Riyadh. After developing a fever, runny nose, cough, and body aches on 29th March, he sought medical care in Riyadh on 4th April. He visited the same hospital where case three was receiving treatment and was admitted to a ward where he shared a room with case two. On 6th April the index case was transferred to Intensive Care Unit (ICU) isolation and intubated. He was tested by RT-PCR, which confirmed MERS-CoV. He had no clear history of exposure to “typical MERS-CoV risk factors”, and investigations to determine the source of infection continue. The index case died on 7th April.
More cases
The second case is a retired 60-year-old male who lives in Riyadh, admitted to ICU on 8th March before being transferred to a ward where he shared a room with the index case on 4th April. This case developed a fever on 6th April and tested positive for MERS-CoV by RT-PCR on 8th April. With “no history of exposure to camels” it is suspected that this case is a secondary healthcare-associated case from contact with the index case.
The third case is another retired 60-year-old male in Riyadh who went to the same hospital before being admitted to a ward on 5th April. After developing shortness of breath on 10th April, he was transferred to the ICU on 15th April and tested positive for MERS-CoV on the same day. Like the second case, this case has no history of exposure to camels and is suspected to be a secondary healthcare-associated case due to contact with the index case. Both the second and third cases were intubated in April and, as of 21st April, were in the ICU.
WHO’s risk assessment
WHO states that these cases do not change the overall risk assessment, and “expects” additional cases to be reported from countries where MERS-CoV is circulating in dromedaries.
“WHO continues to monitor the epidemiological situation and conducts risk assessments based on the latest available information.”
However, WHO “re-emphasises” the importance of “strong surveillance” by all Member States.
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