Avian influenza

Avian influenza (bird flu, or avian flu), is an illness caused by a virus. The virus, called influenza A or type A, usually lives in birds. Sometimes it infects mammals, like humans.

There are many types of influenza A. It was first found in a bird in Italy in 1878. Most types have weak symptoms like conjunctivitis and afluenza-like symptoms. Also breathing problems, like the common cold. It often mutates.

But some types kill birds, and a few kill humans and other mammals. One type of bird flu, called Spanish flu, killed 50 to 100 million people in 1918/1920. Another type, called Asian Flu killed one million in 1957. Another, called Hong Kong Flu, killed one million people in 1968.

A subtype, called H5N1, killed six people in Hong Kong in 1997, but did not kill again until 2003, this time in China. Until the middle of 2005, it was primarily found in southeast Asia but since then has spread to parts of Africa and Europe. It has killed tens of millions of birds and resulted in the slaughter of hundreds of millions of other birds to limit its spread. So far it is mostly a bird disease and rarely infects humans. The concern about H5N1 is that it is constantly evolving at a very fast rate. It might create a human flu pandemic. Governments around the world are spending money to deal with this problem: studying H5N1, creating vaccines, conducting pandemic practice exercises, stockpiling useful flu medication, and many other activities.

2020s spread

United States

The CDC says farm workers wear personal protective equipment, like N95s, when with sick farm animals. The sick farm animals could have H5N1, which could spread the virus. Yet, workers keep getting sick. This may be due to workers' fear of losing their job. This may also be due to employers and state officials not letting CDC inspectors into dairy farms.

As of July 2024, 11 humans sick with H5N1 were found in the USA. All of the sick humans found were dairy farm workers.