Mers outbreak in Saudi Arabia puts health experts on high alert

Most previous outbreaks have been traced back to people working in close contact with camels – JOHN WESSELS/AFP via Getty Images

Health agencies are racing to determine the origins of a Mers outbreak in Saudi Arabia, after three people with no direct contact to camels contracted the coronavirus.

The pathogen, known as Middle East respiratory syndrome, is a close relative of Sars-Cov-2 but has a far higher fatality rate – 35 per cent of confirmed cases have died, according to the World Health Organization (WHO).

The virus comes from dromedary camels, and most previous outbreaks have been traced back to people working in close contact with the mammals or their raw milk.

Yet authorities have not been able to link the current outbreak – which was detected when a 56-year-old school teacher in the capital Riyadh went to hospital in early April – to the animals, raising concerns that milder cases could be spreading undetected.

The WHO expects that less serious and asymptomatic cases have historically been missed, which could also affect the overall case fatality rate.

“There was no clear history of exposure to typical Mers-CoV risk factors,” the UN agency said in a disease alert this week. “Investigations, including determining the source of the infection, are ongoing.”

Mers was first detected in 2012, when it jumped from camels to humans in Saudi Arabia, and it has since spread to 27 other countries – KHALED DESOUKI/AFP/Getty Images

The first case, a man with underlying health conditions, went to hospital in early April after developing a cough, fever and body aches. He later died from the disease.

But two other men in the same hospital, both aged 60, have also tested positive for the coronavirus – sparking a broad contact tracing effort from health officials, to detect further infections before it can spread further. Dozens of people have been tested.

“Hospitals can either serve as a source of prevention or amplification of transmission,” said Dr Saskia Popescu, an infectious disease epidemiologist at the University of Maryland School of Medicine.

“I’ve spent a lot of time studying Mers healthcare-transmission cases and using those lessons to strengthen healthcare bioprep and honestly, THIS is why we invest in infection prevention programs,” she wrote on X, formerly Twitter.

Mers is ‘still around and still a threat’

Mers was first detected in 2012, when it jumped from camels to humans in Saudi Arabia, and it has since spread to 27 other countries. Globally, 2,204 cases and 860 deaths have been reported, according to the WHO – the vast majority, more than 80 per cent, have been in Saudi Arabia.

Earlier this year, the country also reported a fatal case in Taif – a city 500 miles west of Riyadh, by the Red Sea earlier this year.

There have been several large chains of transmission in healthcare facilities – including the largest outbreak outside of the Middle East, in South Korea in 2015. The country confirmed 185 cases and 38 fatalities as the coronavirus swept through 24 hospitals.

While several Mers treatments and vaccines are in clinical development, unlike Covid-19 none have been carried through clinical trials and approved by regulators.

“[This is] a good reminder that we don’t have any proven antiviral treatments, vaccines or rapid diagnostics for Mers,” said Dr Tom Fletcher, an infectious disease specialist at the Liverpool School of Tropical Medicine.

The WHO said the latest cases do not change the overall risk assessment, though it “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”.

The health analytic firm Airfinty, which monitors disease outbreaks globally, said there was a “high threat” for the city Riyadh.

“Mers-CoV [is] still around and still a threat,” Prof Peter Horby, director of the Pandemic Sciences Institute at the University of Oxford said on X. “[Saudi Arabia] has great experience of detecting and controlling health-care associated MERS transmission – other places are less aware and less prepared.”

Prof David Heymann, Professor of Infectious Disease Epidemiology at the London School of Hygiene and Tropical Medicine, said there had been “no change in epidemiology” with these infections.

He added: “The index case is not the first case but was likely infected from the first case  – they are looking for that case now.”

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