Deadly Mers virus has been infecting camels for years, study shows

The research strengthens suggestions that camels play a key role in the spread of the deadly coronavirus.

Reseachers found antibodies for Mers in three quarters of camel samples, and the Mers infection in camels matched that in humans. EPA/SPA / HO

DUBAI // The potentially deadly Mers virus has been infecting camels for more than 20 years, new research suggests.

Camels are thought to play a key role in the spread of the coronavirus. The new findings mean early cases in human beings probably went unnoticed and could have been dismissed as a common flu.

Researchers took archived blood samples dating from 1992 from more than 260 camels in Saudi Arabia. They found antibodies for Mers in three quarters of the samples, and the Mers infection in camels matched that in humans.

The research shows the virus is “extraordinarily common” in camels and has been for at least 20 years, according to Ian Lipkin, of Columbia University in the United States, the author of the study.

Dr Ulrich Wernery, a director of the central veterinary research laboratory in Dubai, who has also carried out research suggesting camels could be responsible for passing Mers to humans, agreed that the virus has been around in the animals for decades.

“Maybe 20, 30, 40 years,” said Dr Wernery, who was not involved in the latest paper. “The virus has been around much longer than we thought. I am sure camels produce antibodies for many viruses and Mers is one of them.”

The research was carried out using blood, nasal and rectal samples from more than 200 one-humped camels across the country, as well as from goats and sheep.

The researchers found no sign of Mers in the goats or sheep. But 74 per cent of camels had antibodies in their blood – meaning they were previously infected with either Mers or another closely-related virus.

While it remains unknown how people contract the disease, the results highlight the importance of investigating camels’ role in transmission to people.

“In some parts of Saudi Arabia, two thirds of young animals have an infectious virus in their respiratory tracts,” said Mr Lipkin. “It is plausible that camels could be a major source of infection for humans.”

Mr Lipkin said Mers appeared to have stayed relatively stable since 1992 and guessed that some human cases went unnoticed and may have been generically labelled as an unexplained respiratory disease.

Dr Wernery also believes Mers has been infecting humans for longer than officially recorded but a lack of advanced laboratory testing meant scientists did not know what they were dealing with.

“Mers did not suddenly crop up one-and-a-half years or two years ago,” he said.

“People were complaining of flu-like symptoms and most probably doctors thought it was bronchitis or the flu because we did not have the equipment or the testing we have now.”

Dr Wernery said while there was no evidence to suggest how the virus is transmitted to humans, he believed as more research was carried out scientists would eventually be able to pinpoint the animals as a host of the respiratory syndrome.

Globally there have been 182 confirmed cases of the virus, of which 79 have died, since September 2012.

Symptoms include acute, serious respiratory illness with fever, cough, shortness of breath and breathing difficulties. Most patients have had pneumonia, and many had gastrointestinal symptoms, including diarrhoea. Some patients have suffered kidney failure.

The UAE is the second-most prevalent country for Mers after Saudi Arabia, said International SOS, a company of experts in global health issues, last month.

Other cases have been found in Jordan, Qatar and Tunisia. Some cases have also been reported in France, Germany, Italy and Britain, but all have had some links to travel in the Middle East.

Mr Lipkin warned that Mers could still evolve into a form that spreads more easily among people and advised public-health officials to take preventive measures in the Middle East, where camels are kept for meat, racing and as pets.

This month, a 66-year-old Emirati camel owner in Abu Dhabi became the latest person to be infected with the Mers coronavirus. He was found to have the virus after complaining of respiratory problems.

As yet, there is no vaccine for Mers and treatment is mainly supportive.

Previous studies have shown bats to be a source of the virus. Subsequent research has focused on camels as intermediate hosts, given humans’ limited contact with bats. The study has been published online in mBio, the journal of the American Society for Microbiology.