In confirming the five latest Middle East respiratory syndrome coronavirus (MERS-CoV) cases in Saudi Arabia, the World Health Organization (WHO) today signaled that four of the cases were in a cluster in which the first patient had contact with camels.

Also today, it was revealed that Dutch and Qatari scientists have isolated and cultured a MERS-CoV from a camel in Qatar, and there are plans to conduct a serologic survey and a case-control study in that country in the effort to determine whether camels are passing the virus to humans.

Evidence of MERS-CoV has been found in camels in several countries, including Qatar, implicating the animals as a source of human infections, but the link has not been conclusively shown.

WHO updates

The WHO in its statement today recognized five cases, including one death, that were reported by Saudi Arabia on Mar 14. All the patients are from the Riyadh area.

The fatal case was in a 19-year-old man who had underlying medical conditions and a history of exposure to animals, including camels, the agency said. He became ill on Mar 1, was hospitalized on Mar 7, and died shortly afterward.

Three of the other case-patients had contact with the 19-year-old, according to the WHO. They were:

A 22-year-old woman who became mildly ill on Mar 10 and is in stable condition

An 18-year-old woman who became mildly ill on Mar 14 and has since recovered

A 53-year-old man who has no symptoms; the statement didn't specify when he was tested

The WHO didn't say whether these four patients are related, but an Associated Press report last week said the two young women were sisters of the 19-year-old.

The other case noted by the WHO is in an 83-year-old man from Riyadh who has underlying medical conditions and got sick on Feb 24. He was hospitalized on Mar 1 and is in critical condition. The agency said he has no history of contact with animals or other MERS patients.

Several previous family clusters of MERS cases have been reported since the virus was identified in 2012. The virus does not appear to spread very readily from person to person, but it can do so with close contact.

In related developments, yesterday the WHO acknowledged two earlier MERS cases reported by Saudi Arabia.

One case, announced by Saudi Arabia on Feb 26, involved a 56-year-old woman from the Riyadh region who has underlying medical conditions, the agency said. She became ill on Feb 12 and was hospitalized on Feb 22. She had no known contact with animals or other MERS patients. The statement did not describe her condition.

The other infection, which Saudi officials announced Mar 6, is in an 86-year-old Riyadh man who has no symptoms, the WHO said. He is reported to have had contact with a previous MERS patient.

With the announcements yesterday and today, the WHO's count of confirmed MERS cases has reached 196, including 83 deaths.

Research in Qatar

Meanwhile, a news report from Qatar today said a team of Qatari and Dutch scientists succeeded in isolating and culturing a MERS-CoV, and a Dutch member of the team explained that the virus came from a camel. The news story was published by the Qatari news outlet The Peninsula.

In e-mailed comments to CIDRAP News, Bart L. Haagmans, PhD, a virologist with Erasmus Medical Center in the Netherlands, noted that previous studies detected MERS-CoV genetic material in nasal swabs from camels in Qatar, Saudi Arabia, and Egypt.

"Now we were able to culture the virus from one of the swabs taken from a dromedary camel. We are now in the process of further characterizing this virus," he said.

"The virus we now [have] cultured is the first one isolated from a dromedary camel," he added.

"The next step is to prove that the virus detected in dromedary camels indeed is the one that is transmitted to humans, that there is zoonotic transmission," Haagmans said. "This possibly can be accomplished by a serosurvey testing different groups of humans in Qatar."

The Peninsula story mentioned plans for a national serologic survey, with screening of "animals and workers," to help identify risk factors for MERS-CoV infection and the source of the virus. The study was recommended by the WHO, it noted.

In addition, Haagmans said there are "definite plans for a case-control study in Qatar" with the same goals. "A detailed case-control study may give you insight in the risk factors that are associated with the zoonotic transmission," he said. "Based on these results one can take the appropriate measures to downscale this risk of zoonotic transmission."

The work on isolating the virus involved Qatar's Supreme Council of Health and Ministry of Environment along with Erasmus Medical Center, with WHO support, according to the news story. It said the Netherlands' Institute for Public Health and the Environment will participate in the serologic survey.

See also:

Mar 18 WHO update

Mar 17 WHO MERS update

Mar 18 The Peninsula story