Proliferation of bird flu outbreaks raises risk of human pandemic

The global spread of bird flu and the number of viral strains currently circulating and causing infections have reached unprecedented levels, raising the risk of a potential human outbreak, according to disease experts. Multiple outbreaks have been reported in poultry farms and wild flocks across Europe, Africa and Asia in the past three months. While most involve strains that are currently low risk for human health, the sheer number of different types, and their presence in so many parts of the world at the same time, increases the risk of viruses mixing and mutating - and possibly jumping to people. "This is a fundamental change in the natural history of influenza viruses," Michael Osterholm, an infectious disease specialist at University of Minnesota, said of the proliferation of bird flu in terms of geography and strains - a situation he described as "unprecedented".