Nigeria, Feb. 10 -- Bird flu, also called avian influenza, is a disease that mostly affects birds. However, in rare cases, it can spread to humans. This can be dangerous, so it's important to understand what bird flu is and how to prevent it.

What is Bird Flu?

Bird flu is caused by viruses that infect birds, especially chickens, ducks, and other poultry. Some types of bird flu are mild, but others, like H5N1 and H7N9, can be deadly to birds and humans.

Humans usually get bird flu through direct contact with infected birds, their droppings, or contaminated surfaces. It does not spread easily from person to person, but in some cases, it has happened.

Signs of Bird Flu in Humans

If a person gets bird flu, they may experience:

Fever and...