A respiratory virus that has killed dozens of people, mainly in the Middle East, is widespread in camels and may be jumping directly from camels to humans, said a study on Tuesday.
Called Middle East Respiratory Syndrome, or MERS, it has killed 79 of the 182 people infected since September 2012, according to the World Health Organization.
The virus is related to SARS, which killed about 800 people globally in a 2003 outbreak. Camels or bats are suspected as possible animal reservoirs of MERS, though there has been little hard evidence.
But senior study author Ian Lipkin of Columbia University said research now shows the virus is "extraordinarily common" in camels and has been for at least 20 years.
"In some parts of Saudi Arabia, two-thirds of young animals have the infectious virus in their respiratory tracts," he said. "It is plausible that camels could be a major source of infection for humans."
Lipkin worked on the study with colleagues at the US National Institute of Allergy and Infectious Diseases and lead author Abdulaziz Alagaili of King Saud University in Riyadh. It was published in the journal mBio on Tuesday.
Researchers took blood samples as well as rectal and nasal swabs from more than 200 camels in Saudi Arabia in November and December of 2013.
They analyzed the samples using mobile laboratory technology and found antibodies for MERS as well as active virus, particularly in the nasal secretions of younger camels.
Overall, 74 percent of camels sampled countrywide had antibodies to MERS-CoV (coronavirus), the study said.
The team also analyzed archives of blood samples from dromedary camels - the most common species - taken from 1992 to 2010, and found evidence of MERS going back two decades.
"The virus that has been identified in these camels is identical to the virus that has been found in humans with disease," Lipkin said.