* MERS virus has killed at least 327 people, infected 850
* Scientists say detecting virus in air is a concern
* WHO says camel farmers, workers should take precautions
By Kate Kelland
LONDON, July 22 (Reuters) - Saudi scientists have found gene fragments of the deadly Middle East Respiratory Syndrome (MERS) virus in air from a barn housing an infected camel and say this suggests the disease may be transmitted through the air.
MERS, a serious respiratory illness caused by a virus known as a coronavirus (CoV), has infected at least 850 people since it first emerged two years ago and killed at least 327 of them, according to latest figures from the European Centre for Disease Prevention and Control (ECDC).
The vast majority of human cases have been in Saudi Arabia, but isolated MERS cases have been reported across Europe and in Asia and the United States in people linked who have recently travelled in the Middle East.
Scientists are not sure of the origin of the virus, but several studies have linked it to camels and some experts think it is being passed to humans through close physical contact or through the consumption of camel meat or camel milk.
However, in this latest study, published in the online journal of the American Society for Microbiology mBio, scientists said the detection of the virus in air samples was concerning and needed to be followed up.
"The clear message here is that detection of airborne MERS-CoV molecules, which were 100 percent identical with the viral genomic sequence detected from a camel actively shedding the virus in the same barn on the same day, warrants further investigations and measures to prevent possible airborne transmission of this deadly virus," said Esam Azhar, an associate professor of medical virology at King Abdulaziz University in Jeddah who led the study.
Viruses that spread through air - such as flu viruses for example - are far more likely to spread swiftly and widely in human populations than those that can only move from an animal to a person, or from person to person, via direct contact.
For their research, Azhar's team collected three air samples on three consecutive days from a camel barn near Jeddah owned by a 43-year-old male MERS patient who later died from the disease.
Four of the man's nine camels had shown signs of nasal discharge the week before the patient became ill, and he had applied a topical medicine in the nose of one of the sick camels a week before experiencing symptoms.
Using a laboratory technique called reverse transcription polymerase chain reaction (RT-PCR) to detect levels of particular genes, the scientists found that the first air sample, collected on Nov. 7, 2013, contained genetic fragments of the MERS virus.
This was the same day that one of the patient's camels tested positive for the disease, they explained in a report of their work.
The other samples did not test positive for the MERS virus - suggesting short or intermittent shedding of the virus into the air surrounding the camels, Azhar said.
Further tests of the first air sample confirmed the presence of MERS genetic sequences and showed that the fragments were identical to fragments detected in the camel and its sick owner.
"This study also underscores the importance of obtaining a detailed clinical history with particular emphasis on any animal exposure for any MERS case, especially because recent reports suggest higher risk of (MERS) infections among people working with camels," Azhar said.
The World Health Organisation and the Saudi Health Ministry have advised camel farm and slaughterhouse workers to take precautions against MERS by ensuring good hygiene, including frequent hand washing after touching animals, facial protection where feasible, and wearing of protective clothing.
(Reporting by Kate Kelland, editing by Ken Wills)