It's extremely rare for people to catch the disease, so very few humans have had bird flu.
This is because the only confirmed cases involved people catching it from a live bird in one of the affected areas.
Many countries across Europe and south-east Asia have been affected by the current outbreak, but by April 2006 only around 100 people were reported to have died.
The bird flu virus causes fever and flu symptoms in humans. They suffer from coughing fits and eventual pneumonia.
There are no confirmed cases of a human catching it from another human.