Canadian SARS expert Dr. Allison McGeer of Toronto's Mount Sinai Hospital is part of the team, which began its work Tuesday.
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.
The MERS virus — the acronym is short for Middle Eastern respiratory syndrome — comes from the same family as the SARS coronavirus. McGeer helped lead Toronto's response to SARS, and actually contracted SARS in the early days of the outbreak.
The mission is an attempt to find answers to some of the many questions that persist about the puzzling new MERS virus.
More than a year after the first known infections occurred, the world still has no idea where the virus lives in nature, how people are contracting it, how often and under what conditions person-to-person spread occur and whether the genetic sequences of the viruses suggest they are evolving to infect people more easily.
In fact, although there have been 55 confirmed cases — the most recent announced Tuesday by Saudi Arabia — the genetic blueprints of only four viruses have been publicly posted for scientific scrutiny.
The lack of information on the virus has raised serious concerns among public health agencies and governments trying to assess the threat it poses.
During the WHO's annual meeting, World Health Assembly, at the end of May both WHO leaders and country delegations repeatedly pressed Saudi Arabia for more information.
The frank talk at the Geneva meeting hasn't led to an increase in the data flow. Since then, the Saudis have reported eight additional cases via terse press releases posted on the Ministry of Health's website. These statements have typically revealed little more than the general region in the country where the infection was spotted and the age and gender — sometimes — of the person infected.
The statements have not revealed whether the cases are linked to previous infections, which is information needed to gauge whether there may be secondary spread going on in Saudi Arabia.
An infectious diseases expert who has been watching the situation closely said the Saudi approach to information sharing "borders on irresponsible at this point."
Michael Osterholm, director of the Center for Infectious Diseases Research and Policy at the University of Minnesota, said it is clear Saudi health authorities either don't know what is going on with the MERS virus or are sitting on data for some reason.
"They have to know more. They just have to know more. And to suggest that they don't means that it's either an incompetent investigation, or they're withholding information," Osterholm said.
"Public Health 101 would mean you would understand things like incubation periods, potential secondary attack rates, likely source of exposure, potential animal reservoirs and issues like that.
"If that's not known, then I question whether the people who are in charge should be in public health and in charge. If they, on the other hand, have withheld the information for whatever reason, that also is equally damning."
The team in Saudi Arabia 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 said the group includes representatives from the UN's Food and Agriculture Organization and the World Organization for Animal Health, better known as the OIE. WHO, FAO and OIE often work together on disease outbreaks that involve animals and people.
The group began its work Tuesday, meeting with Saudi Ministry of Health officials to flesh out terms of reference, Hartl said. 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.
"They (also) want to get a better idea of the true severity spectrum of MERS," Hartl said.
Of the 55 confirmed MERS cases to date, 30 have been fatal. Infections appear to originate in 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 have occurred in Saudi Arabia, which has reported a steady stream of infections since early May.