The coronavirus-type infection recorded in a 28-year-old man in Al Ain on June 8 showed that the camel-linked Middle East respiratory syndrome, or Mers, continues to be a health risk.
It was the first reported case of the virus in 2023, with the majority of all known cases having links to the Middle East.
Despite the world’s attention shifting towards Covid-19, and related pathogens that continue to circulate, the latest World Health Organisation report on Mers shows that the coronavirus is still on the wane.
The most recent recorded incident in Al Ain was the first reported in 2023 by health authorities worldwide or the WHO.
From 29 December 2021 to 31 October 2022, four cases were reported to WHO by the Ministry of Health of the Kingdom of Saudi Arabia, with no deaths.
Figures show there were 19 cases of Mers in 2021, 17 of them in Saudi Arabia and two in the UAE. Eight of that year’s cases were fatal.
Numbers have fallen dramatically since their peak in 2015 when there were 492 laboratory-confirmed cases of the disease.
Mers-CoV, a coronavirus first identified in 2012, is much more deadly to infected people than SARS-CoV-2 but is much less easily transmitted.
University of Liverpool
Since the disease was first detected a decade ago, there have been 2,613 confirmed cases, about 84 per cent of which were in Saudi Arabia.
According to the WHO, the global death toll from known cases of Mers is 858, although the EU's European Centre for Disease Prevention and Control reports that the number is higher, with 945 fatalities related to the virus.
Transmitting virus to humans
Camels continue to act as a “reservoir” for the disease and to transmit the virus to people, although some cases are still recorded in humans who have not had contact with the animals.
Dr Ulrich Wernery, scientific director of the Central Veterinary Research Laboratory in Dubai, said better hygiene and other virus control measures have helped to reduce the number of people infected with the virus.
“The cases in humans have dropped dramatically. We see very few. I believe if it continues like this, it will die out, like Sars,” he said, referring to Severe Acute Respiratory Syndrome, which caused more than 8,000 infections and almost 800 deaths between 2002 and 2004.
“The virus is still around. The source of the infection is the camel – there’s no doubt, we’ve known that for many, many years.”
He said the centre continues to isolate the virus in some postmortem samples from calves that have died from other causes.
Person-to-person spread happens rarely and it was not thought to be a factor in any of last year’s cases. Transmission is usually in a health care setting or between people in the same household.
A large proportion of Mers cases are in people who work with camels and have picked up the virus from an infected animal.
“I believe that the virus will still circulate in camel herds and camel populations,” Dr Wernery said.
“The contact with people will be much, much less because people are more aware. People will wear masks if they’re treating camel calves and gloves.”
Calves are protected from Mers in their infancy by antibodies against the virus in the milk they consume from their mothers.
However, the level of antibodies in the milk declines after four to six months, leaving the animal open to infection should it be exposed to the virus.
For a short period, until the young camel starts to produce its own antibodies, it may have mild symptoms, such as a nasal discharge that contains the virus. It is at this point the camel may infect a person, who is at risk of a much more serious infection.
Risk factors remain
Among the researchers working on Mers is Prof Julian Hiscox, a professor of infection and global health at the University of Liverpool.
He is part of a multimillion-dollar project, also involving SARS-CoV-2, the virus that causes Covid-19, looking at ways to test treatments for infected people.
Risk factors for people infected with Mers-CoV are typically the same as those for people infected with SARS-CoV-2, he said, including being obese and having kidney disease.
“The treatments for Mers are to do with specialist care rather than directly targeting the virus,” he said.
“You’re treating the symptoms around the infection and the body’s response to disease.”
Some generic therapies used to treat Covid-19 may be effective against Mers, he said, and specific therapies, such as those using monoclonal antibodies, which involve large numbers of identical laboratory-made antibodies, could be tailored to treat Mers patients.
Trials are continuing with vaccines for camels and for people, with Prof Hiscox saying that those at a high risk of being infected, such as people who handle camels, may want to be immunised.
While case numbers in people have dwindled, he said it was unlikely the disease would disappear given that camels remain a reservoir and other creatures may be infecting them.
“There’s a lot of evidence of Mers in camels in different parts of the world, not just the Gulf states,” he said.
“We see continuous spillover into humans … sometimes these diseases wax and wane. In the future, we could be on an upwards trend.”
