According to a study published in the Public Library of Science journal PLoS ONE, the avian influenza strain found in Nigeria is genetically different from previous African outbreaks.
Scientists have so far focused on the H5N1 bird flu virus and H7 avian flu viruses as candidates for the next pandemic, but new circumstantial evidence suggests that the H9 viruses could also cause a future pandemic.
A single mutation in the H9 strain can make the virus more pathogenic and capable of infecting humans.
Researchers believe that the H9 strain is responsible for the recent outbreak, carried to Africa by wild birds migrating to the continent. It also affected at least four children in Hong Kong. The virus was also found in birds, pigs and other animals in Europe and Asia.
The virus doesn't make birds sick, so it often goes unnoticed. So far, the most deadly strain of bird flu, the H5N1 strain of bird flu, has killed more than 230 people worldwide since late 2003 through contact with infected birds, with about half of the cases in Indonesia.
Other strains of avian influenza viruses include H7N3, H7N7 and H9N2 that also have the potential to be transmitted to humans.
