Disease Outbreak News, Middle East respiratory syndrome coronavirus - Kingdom of Saudi Arabia

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13 March 2025

Situation at a glance

This is the bi-annual update on the Middle East respiratory syndrome coronavirus (MERS-CoV) infections reported to the World Health Organization (WHO) from the Kingdom of Saudi Arabia (KSA). From 6 September 2024 to 28 February 2025, four laboratory-confirmed cases of MERS-CoV infection, including two deaths, were reported to WHO by the Ministry of Health of the KSA. One of the four cases was a secondary case exposed to the virus in a healthcare facility (nosocomial transmission). Close contacts of the four cases were followed up by the Ministry of Health. No additional secondary cases have been detected. The notification of these four cases does not alter the overall risk assessment, which remains moderate at both the global and regional levels. The reporting of these cases shows that the virus continues to pose a threat in countries where it is circulating in dromedary camels, particularly those in the Middle East.

Description of the situation

Between 6 September 2024 and 28 February 2025, the Ministry of Health (MoH) of the Kingdom of Saudi Arabia (KSA) reported four cases of Middle East respiratory syndrome coronavirus (MERS-CoV) infection, including two deaths, with the last case being reported on 4 February 2025. The cases were reported from the Hail (2), Riyadh (1) and the Eastern (1) Provinces of the KSA (Figure 1). Laboratory confirmation of the cases was performed by real-time polymerase chain reaction (RT-PCR) between 8 November 2024 and 4 February 2025.

All cases involved males aged between 27 and 78 years, and all presented with comorbidities. None were health workers, and from investigations only one was found to have indirect contact with dromedary camels (hosts of MERS-CoV) and their raw products (milk).

Two cases, with symptoms onset in November 2024, were identified within the same hospital. The first case was confirmed on 11 November through RT-PCR testing, and follow-up on close contacts revealed a secondary case that shared the same hospital room and developed symptoms subsequently. Neither of the two patients had direct or indirect contact with dromedary camels, including consumption of raw camel milk in the 14 days prior to the onset of symptoms.

Since the first report of MERS-CoV in KSA in 2012, a total 2618 laboratory-confirmed cases of MERS-CoV infection, with 945 associated deaths (CFR 36%), have been reported to WHO from 27 countries, across all six WHO regions. The majority of cases (2209; 84%), have been reported from KSA, including these newly reported cases. Since 2019, no MERS-CoV infections have been reported from countries outside the Middle East.

Figure 1. Geographical distribution of MERS-CoV infections between 6 September 2024 to 28 February 2025 by city and region, KSA (n=4).

Figure 2: Epidemic curve of MERS-CoV infections (n=2209) and deaths (n=864) reported in KSA between 2012-2025*

Epidemiology

Middle East respiratory syndrome (MERS) is a respiratory illness caused by a coronavirus (MERS-CoV). The fatality rate among confirmed cases is around 36%, though this may be an overestimate since milder cases often go undetected. The case fatality ratio (CFR) is calculated based solely on laboratory-confirmed infections, which may not reflect the correct mortality rate.

Humans contract MERS-CoV through direct or indirect contact with dromedary camels, the virus’s natural host and zoonotic reservoir. While human-to-human transmission is possible, it has mainly occurred in close-contact situations, particularly in healthcare settings. Outside these environments, there has been limited human-to-human transmission to date.

MERS can present with no symptoms, mild respiratory issues, or severe illness leading to acute respiratory distress and death. Common symptoms include fever, cough, and breathing difficulties, with pneumonia frequently observed, though not always present. Some patients also experience gastrointestinal symptoms such as diarrhoea. Severe cases may require intensive care, including mechanical ventilation. Those at higher risk of severe outcomes include older adults, individuals with weakened immune systems, and those with chronic conditions like diabetes, kidney disease, cancer, or lung disorders.

The number of MERS-CoV infections reported to WHO has substantially declined since the beginning of the COVID-19 pandemic. Initially, this was likely the result of epidemiological surveillance activities for COVID-19 being prioritized. The similar clinical picture of both diseases may result in reduced testing and detection of MERS-CoV infections. In addition, measures taken to reduce SARS-CoV-2 transmission (e.g., mask-wearing, hand hygiene, physical distancing, improving the ventilation of indoor spaces, respiratory etiquette, stay-at-home orders, reduced mobility) also likely reduced opportunities for onward human-to-human transmission of MERS-CoV. Potential cross-protection conferred from infection with or vaccination against SARS-CoV-2 and any reduction in MERS-CoV infection or disease severity and vice versa has been hypothesized but requires further investigation.

No vaccine or specific treatment is currently available, although several MERS-CoV-specific vaccines and therapeutics are in development. Treatment remains supportive, focusing on managing symptoms based on the severity of the illness.

Public health response

Apart from the two cases linked to healthcare settings, the Ministry of Health did not detect any additional secondary infections. Triage for respiratory diseases has been implemented in the concerned hospital to enable early detection of patients with respiratory symptoms. In addition, comprehensive refresher training on the case definition has commenced for all health and care workers to ensure early detection of cases.

WHO risk assessment

The notification of these four additional 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, and that cases will continue to be exported to other countries by individuals who were exposed to the virus through contact with dromedaries or their products (consumption of raw camel milk), or in a healthcare setting. WHO continues to monitor the epidemiological situation and conducts risk assessment based on the latest available information.

WHO advice

Based on the current situation and available information, WHO re-emphasizes the importance of strong surveillance by all Member States for acute respiratory infections, including MERS-CoV, and to carefully review and investigate any unusual patterns.

Human-to-human transmission of MERS-CoV in health care settings has been associated with delays in recognizing the early symptoms of MERS-CoV infection, delayed triage of suspected cases, and delays in implementing infection prevention and control (IPC) measures. IPC measures are critical to prevent the possible spread of MERS-CoV between people in health care facilities. Health workers should consistently apply standard precautions, including risk assessment for any new onset of symptoms of respiratory infections, consistently with all patients, at every interaction in health-care settings.

Contact and droplet precautions, which include patient placement in single rooms with dedicated care equipment, and the use of personal protective equipment (PPE) such as clean non-sterile gown, gloves, eye protection and a well-fitting medical mask, should be added to standard precautions when providing care to patients with MERS-CoV. Ventilation rates in patient care rooms should meet or exceed 60 litres per second per patient (or 6 air changes per hour). Airborne precautions should be applied when performing aerosol-generating procedures or in settings where aerosol-generating procedures are conducted, including the use of procedure rooms with ventilation rates meeting or exceeding 160 litres per second (or 12 air changes per hour). Early identification, case management and isolation of cases, quarantine of contacts, together with appropriate IPC measures in health-care settings and public health awareness can prevent human-to-human transmission of MERS-CoV.

MERS-CoV infection 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 animals, particularly dromedaries, when visiting farms, markets, or barn areas where the virus may be circulating. General hygiene measures should be adhered to, such as regular hand washing before and after touching animals and avoiding contact with sick animals.

Food hygiene practices should be observed. People should avoid drinking raw camel milk, contact with camel urine or eating camel meat that has not been thoroughly cooked. The consumption of raw or undercooked animal products, including milk and meat, carries a high risk of infection from pathogens that may cause disease in humans. Animal products that are processed appropriately through cooking or pasteurization are safe for consumption. Foods that have gone through these processes should be handled with care to avoid cross contamination with uncooked/unsafe foods. Camel meat and camel milk are nutritious products that can continue to be consumed after cooking, pasteurization or other thermal treatments.

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

Further information

Citable reference: World Health Organization (13 March 2025). Disease Outbreak News; Middle East Respiratory Syndrome coronavirus – Kingdom of Saudi Arabia. Available at: http://www.who.int/emergencies/disease-outbreak-news/item/2025-DON560