‘Diseases’ which we know as H1N1 or H5N1 are actually the names of influenza viruses.
Some of these have become notorious because they are able to cause severe, life-threatening infections.
These viruses are named after two types of molecules found on their surface.
The H stands for Haemagluttinin and at the moment, 18 subtypes of these molecules have been identified in influenza viruses, named H1, H2 and so on.
These molecules help the virus enter healthy body cells.
The N stands for Neuraminidase and currently, 9 subtypes of influenza neuraminidases have been identified, called N1 to N9.
These molecules help viruses ‘leave’ infected cells as they spread through tissue.
By using these molecules, scientists are able to determine the type of viruses and hence, the labels H1N1 (also known as swine flu) or H5N1 (bird flu).