Bird flu has catastrophic potential

Q: What is avian flu?

Like humans and other species, birds are susceptible to flu. There are 15 strains of bird - or avian - flu. The most contagious types, which are usually fatal in birds, are H5 and H7. The type currently causing concern is the deadly H5N1 strain.

Even within this strain, variations are seen, and slightly different strains are being seen in the countries affected in this outbreak.