Flu pandemics

According to multiple online sources, other than the current H1N1 'swine' flue, notable pandemics which occurred recently were the 1918 Spanish flu, the 1957 Asian flu and the 1968 Hong Kong flu. I shall be describing each of the 3 pandemics briefly.

The Spanish flu was a severe pandemic that spread globally, affecting even minor countries. About 50 - 100 million people were killed in this pandemic. It had an infection rate of 50% and killed about 1/5 of the infected. Earlier, before the flu was discovered, patients infected with the Spanish flu were diagnosed as having dengue or other diseases which had similar symptoms. The most distinctive symptom of the flu was bleeding from parts of the body which produced mucous, such as the nose. The origins of the flu were unknown, but some speculated that it originated from China.

The Asian flu pandemic was actually a type of avian flu which originated from China. Online sources state that the flu was actually developed from a mutation of the flu virus in wild ducks, which then quickly spread to humans. It affected mainly Asian countries, but reached the US very quickly. It spread to Singapore by about February 1957. About 1-4 million were killed in this pandemic.

The Hong Kong flu pandemic involved from a flu, which developed genetically from another category of flu virus. The flu originated from Hong Kong and spread globally, killing approximately 1 million.

By the way, an epidemic is a disease which is widespread throughout a locality (you could think of a locality as a relatively insignificant area, as compared to a country or a continent). A pandemic is an epidemic on a large scale.