The global threat that most preoccupies the world's business leaders is the deadly H5N1 bird flu virus, according to a study released Thursday at the World Economic Forum.
Other global risks, such as terrorist attacks and the possibility of an even bigger oil price shock, were deemed just as dangerous, but less likely to happen in the coming year, said the "Global Risks 2006" report.
The H5N1 bird flu strain has ravaged poultry stocks in Asia since 2003 and recently spread to Europe through migratory birds. World health authorities fear the disease could mutate into a form that spreads easily from person-to-person, sparking a flu pandemic that could kill millions of people.
So far, though, human cases of the disease have been mostly limited to people who have come into direct contact with infected birds. According to the World Health Organization, 83 people have died of the disease since 2003.
"If the avian flu H5N1 virus mutates to enable human-to-human transmission, it may disrupt our global society and economy in an unprecedented way," said the 22-page risk study, which was released by a panel of companies and experts.
Death tolls could be on the level of the 1918-1919 Spanish flu pandemic, which is estimated to have killed between 40 million and 50 million people worldwide, it said.
The report also said it was very likely that 5 million more people would become infected with HIV and tuberculosis this year.
While the report predicted a number of small-scale terrorist attacks in 2006, it said large-scale simultaneous attacks were less likely, primarily because the capability of terrorists to coordinate their activities had diminished.
"Terrorist attacks involving aircraft and high explosives have already had a massive global impact," the study said, but added, "The capacity of terrorist organizations to act globally in a coordinated way has diminished."
The risk of a major attack will rise in coming years, however, it said.
The report warned of other possible severe shocks, such as an oil price spike to $100 a barrel or an earthquake hitting Tokyo, but said those risks had a low likelihood of occurring.
"The world suffered an oil-price spike above $70 in 2005," the study said. "The world's reliance on hydrocarbons and growing concerns about the geopolitics of supply mean that oil prices will inevitably be an issue of concern in 2006 and beyond."
But even if oil prices should rise above $100, it is "relatively unlikely" that they would remain so high for an extended period, it said.
It said the Pakistan earthquake provided a lesson that the world lacks the capacity to respond sufficiently to major disasters and "a warning that many parts of the world remain highly vulnerable to natural disaster."
The Forum study was based primarily on contributions from Marsh & McLennan Companies, Inc., Merrill Lynch and Swiss Reinsurance Co. and the Wharton School at the University of Pennsylvania.