The Source of the Spread

The cause of bird flu was the A virus of type influenza that spread between the poultry. This virus was afterwards found also could spread to the other species like the pig, the cat, the dog, the tiger, and humankind. The A virus of type influenza had several sub-types that were marked by the Hemagglutinin existence (H) and Neuramidase (N). There were 9 H variants and 14 variants of N. Virus bird flu that was contagious at this time was the sub-type H5N1 that had incubation time for 3-5 days.