What are the different kinds of avian influenza?
There are 15 different strains of bird flu. The mildest – the low pathogenic form – often goes unnoticed, except that hens may produce fewer eggs. More severe kinds spread rapidly and kill many of the birds they infect. The virus that hit poultry in B.C.’s Fraser Valley in February 2004 – the H7N3 virus – is highly pathogenic.