Why is flu called flu?

Answer 1

The scientific names for the virus strains that cause the flu are derived from the proteins on the virus capsid (coat), and usually some indication of the location from which the virus strain was first obtained or a type of known virus to which the new strain is similar, e.g., "Perth-like".

In the naming convention of viruses, the protein classifications become part of the name as in H1N1; H for the haemagglutinin and N for the neuraminidase. There are different subtypes of viruses using the H and N nomenclature, for example the H5N1 subtype is the Avian (Bird) Flu and H1N1 subtype is the Swine Flu.

The common names usually are based upon where the virus was first discovered, e.g., The Hong Kong Flu, Fujian Flu, etc. or in what animal the virus is endemic, e.g., Swine Flu, Bird Flu, Horse Flu, etc.

See the related question for more information on the naming of flu viruses.

Answer 2

The virus originated as a disease in birds only, but now can also infect humans making direct contact with birds carrying the virus.

Answer 3

It just is. Some Infectious Diseases are caused by bacteria, fungi, parasites, or, as in the case of influenza infections, viruses.

Answer 4

flu is short for influenza