Bird flu refers to an illness caused to a particular host caused be any of species of influenza virus. This bird flu is also called as Avian Influenza in which birds are affected by a particular influenza A virus. It is usually spread from bird to bird. Bird flu is technically caused by H5N1 and H7N9 bird flu viruses. This influenza virus attacks the birds and when humans consume them, they will be affected by this virus, where humans do not have any immunity against the virus and so causes severe effects.
Prevention: There is no treatment for bird flu and the virus is most effective to humans and so prevention can only be done by taking certain precautionary measures like will preferring birds as a source of food better to check them whether they are affected by any virus or not.
In Japan, 23 million people were affected, and 390,000 died. In the Dutch East Indies (now Indonesia), 1.5 million were assumed to have died among 30 million inhabitants. In Tahiti, 13% of the population died during only a month. Similarly, in Samoa in November 1918, 22% of the population of 38,000 died within two months.