What are the other types of the flu?

Answer 1

ABC.

A is the worst, causes pandemics and epidemics

B causes epidemics

C is minimally problematic

If you're talking about strains, you have 9 types of Hemagglutinin and 16 types of Neuraminidase. So H5N1 (swine flue from a couple years ago) has Hemagluttinin number 5 and Neuraminidase number 1

Answer 2

There are two main types of flu that people get sick from : Type A and Type B. Some subtypes of these circulate every year as seasonal flu in the US. There are many subtypes. As, for example, the "Pandemic Swine Flu" is a subtype of the Type A influenza. That is why you see it called A-H1N1/09.

Another virus type is Type C (there is only one strain of this type of virus), humans do get this type and so do pigs, but it causes such mild symptoms that it isn't usually connected with epidemics, just small local outbreaks. Influenza Type B is found in humans and seals and consists of only one type that mutates slowly, but mutates often enough that new immunization vaccines need to be given to keep up with the changes to new mutated strains and maintain immunity. The Type A virus also circulates in animals, such as chickens, ducks, pigs, and horses, etc.

The Type A virus has subtypes that are identified by the differences in the two proteins on their outer shells (capsids), the H and N proteins. The H protein is hemagglutinin and the N protein is neuraminidase. There are currently 16 H subtypes and 9 N subtypes of Type A influenza identified. All of these have been found in wild birds (and that is where the scientists believe they all originated). But only H 1, 2 and 3, and N 1 and 2 are commonly found in humans.

One of the other Type A viruses is H1N2, which was known to have been in China in the 1980's and was not seen again until discovered in 2002, in England, Isreal, and Egypt. H3N2 and H1N1 (not the pandemic one) have been circulating Type A viruses since the 1970's. It is thought that H1N2 was a reassortant of the H3N2 and H1N1 viruses that took the N2 from H3N2 and merged it with the H1 from H1N1 to create the H1N2 subtype.

In each flu season there are typically three main subtypes that surface again or are new from across the world. Since the Southern Hemisphere gets their flu season first, the epidemiologists in the North can monitor in Asia and the Southern Hemisphere to see what types are spreading in outbreaks in those areas and plan our seasonal flu shots to prepare for their spreading into the Northern Hemisphere. New ones are mutating all the time.

One of the other more well known types is the Avian (Bird) Flu H5N1, which is also a Type A flu, and circulates rampantly among birds but rarely in humans. It has not been seen yet at all in birds or humans in the US, but it is known to have infected at least 400 people since 2003 in over ten countries in Europe, Asia, Africa, the Pacific, and the Near East. It has shown a 60% mortality rate, mostly in people under 40. Very few are human to human transmissions.

Another Avian Flu is H7N3 which has been known to very rarely infect humans. It was found in 2006 in England at a poultry farm and, of 103 people exposed, only one person tested positive for the virus. Many had symptoms only of eye infections.

The 2009 Seasonal Flu vaccine was developed to provide immunity to the three main types of flu expected to hit the Northern Hemisphere in addition to the Pandemic A-H1N1/09 flu. These three types include two Type A viruses and one Type B virus:

• A/Brisbane/59/2007(H1N1)-like virus
• A/Brisbane/10/2007 (H3N2)-like virus;
  
• B/Brisbane 60/2008-like antigens.

The Spanish Flu was the pandemic flu of 1918, another Type A H1N1 (another one that is different than the 2009 Pandemic swine flu). Another flu of the A Type was the Russian Flu of 1889 subtype H2N2. In 1977 there was another Russian Flu caused by Type A which was the A/USSR/90/77 (H1N1) subtype. It infected people under age 23. In 1968 there were outbreaks of the Hong Kong flu, Type A H3N2.

A list of more of the Type A Influenza viruses includes :

H1N1, H1N2, H2N2, H2N3, H3N1, H3N2, H3N8, H5N1, H5N2, H5N3, H5N8, H5N9, H7N1, H7N2, H7N3, H7N4, H7N7, H9N2, H10N7