Researchers at the University of British Columbia have synthesized a vaccine that may prevent the spread of West Nile virus in birds, a development that could have a major impact on how the disease spreads. 

Since the West Nile pathogen arrived in North America in 1999, it has infected more than 4,700 Canadians and killed 42.

The virus is transmitted to humans from mosquitoes that have fed on infected birds, so an effective bird vaccine could prevent the spread of the disease to humans, but also protect vulnerable bird species. 

"West Nile virus has been identified as a threat contributing to the extinction of some rare bird species and its presence in common birds facilitates the spread of the disease," says Joanne Young, a UBC vaccine researcher. 

"A bird vaccine would go a long way to helping combat these adverse effects."

Some endangered bird species like the eastern loggerhead shrike and California condor have proven especially susceptible to the virus, with mortality rates approaching 100 per cent in some cases.