A World Health Organization-led group of experts is in Saudi Arabia trying to get to the bottom of what is happening there with the new MERS coronavirus.

A Canadian SARS expert, Dr. Allison McGeer of Toronto's Mount Sinai Hospital, is part of the team.

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Dr. Keiji Fukuda, WHO's assistant director general for health security and the environment, is helping to lead the team investigating the MERS outbreak in Saudi Arabia. (Eugene Hoshiko/Associated Press)

McGeer was recently in Saudi Arabia at the behest of the kingdom's government, helping to investigate a MERS outbreak in a hospital at Al-Ahsa in the eastern part of the country.

WHO Director General Dr. Margaret Chan announced the expert mission to Saudi Arabia during the recent World Health Assembly in Geneva.

The team is led by Dr. Keiji Fukuda, the WHO's assistant director general for health security and the environment, and Dr. Jaouad Mahjour, director of communicable diseases at WHO's Regional Office for the Eastern Mediterranean.

WHO spokesperson Gregory Hartl says the team includes representatives from the UN's Food and Agriculture Organization and the World Organization for Animal Health, better known as the OIE.

The group began its work Tuesday, meeting with Saudi Ministry of Health officials to flesh out terms of reference, Hartl says. The mission is expected to conclude Sunday.

Between 10 and 15 people are on the team, including Dr. Dan Jernigan of the U.S. Centers for Disease Control. Jernigan, who is normally the second in command in the CDC's influenza division, is currently detailed to the CDC's office of surveillance, epidemiology and laboratory services.

Hartl says that among the issues the team hopes to explore is the epidemiology of the infection in Saudi Arabia — in essence, trying to find out how people are contracting the virus. It is still not known where the virus lives in nature or how people are coming in contact with it.

"They [also] want to get a better idea of the true severity spectrum of MERS," Hartl says.

To date there have been 55 confirmed cases of MERS,  the most recent announced Tuesday by Saudi Arabia. Thirty have been fatal. Infections appear to originate from the Middle East, in particular countries on the Arabian Peninsula — Saudi Arabia, Jordan, United Arab Emirates and Qatar.

But spread from those countries has led to infections in Britain, France, Tunisia and most recently Italy. A man who had been visiting family in Jordan became ill after returning to Italy. He passed the virus to a family member and a coworker.

The bulk of the cases — 40, according to the WHO's count — have occurred in Saudi Arabia, which has reported a steady stream of infections since early May. The kingdom has been parsimonious with information about what is happening in its Eastern Province, where most of the cases have occurred.