Origins of MERS virus still puzzles researchers

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One of the earliest known victims of the Middle East Respiratory Syndrome coronavirus -- a retired Saudi military man who owned a herd of camels outside of Jeddah -- almost certainly was infected when he applied a topical medication to the runny nose of one of his sick animals, a new study says.

But the authors of the latest effort to pinpoint the origins of the MERS virus said the farmer's camel was probably an intermediate MERS host, and suggested that bats named for the Egyptian tombs they inhabit may have been the virus' first sanctuary.

In a "brief report" published online by the New England Journal of Medicine, a team of Saudi biomedical researchers used a combination of old-fashioned field investigation and viral genetic sequencing to track down one of the MERS virus' earliest leaps from animal to human. Their inquiries showed that the Saudi victim, who died 15 days after being admitted to a Jeddah hospital with severe shortness of breath, had tended to several camels suffering from an unusual nasal discharge.

One of those camels, the researchers found, carried a virus genetically identical to that found in the blood and nasal passages of the Saudi patient who died. The scientists found evidence that the man's nine camels had transmitted the virus among themselves in the period before the man was infected, since all carried antibodies, and had recovered from any ill effects.

The scientists cited evidence that the MERS virus did not transmit readily from camel to human or from human to human -- at least in November 2013. Three of the patient's friends report having visited the camels daily with the victim, and were uninfected. The victim's 18-year-old daughter was also uninfected.

But a sample of the MERS virus' genetic sequences suggest that the dromedary camels, made mildly ill when exposed, may have been the virus' intermediary host. They cited several studies published earlier suggesting that bats native to several Middle Eastern countries harbor a closely related virus.

One 2013 study discovered that a small fragment of the human MERS virus's genetic sequence was identical to that found in an Egyptian tomb bat caught in Saudi Arabia. But, the authors wrote, the exact origins of MERS, which by late March had killed 86 and sickened at least 206 people worldwide, remains a mystery.



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