Post by JC on Oct 30, 2009 13:16:28 GMT -5
I wrote this summary of what H1N1 is a while ago. It's just some random facts about H1N1.
There are 3 types of influenza virus: types B and C, which only infect humans and have never caused an epidemic, and then there's our friend the type A which infects a wide range of animals, including (obviously) birds, pigs, horses, and humans. Influenza A strains have caused three major flu epidemics in history. The worst was the Spanish flu pandemic in 1918 which killed about 40 million people. Birds were the source of that one!
When the virus mutates as it's passed from one host species to another (i.e. bird to pig, etc.) it causes a likely scenario for a pandemic. When an animal is infected with more than one strain of flu virus, the different strains can undergo genetic recombination if the RNA molecules making up their genomes mix and match during viral assembly in the host. In more simple terms if there are different strains of the virus in a host, they have a big party and start combining to make one big bad virus. Along with mutation, this can lead to what causes these viruses to infect human cells. Since it's an animal virus, we haven't been exposed to that particular strain before so that means we lack immunity and the recombined virus (big bad virus) has the potential to be highly infections. Once it reaches humans, it begins to circulate among us because it can acquire the ability to spread from person to person which then leads to a major human outbreak. And since we all can't resist touching each other and people still don't listen when we say to wash your damn hands, we spread this big bad virus easily.
So what is exactly all this H1N1 coding anyway? Different strains of influenza A are given standardized names; for example the strain that caused the 1918 flu was also called H1N1. The name identifies which forms of two viral surface proteins are present: hemagglutinin (H) and neuraminidase (N). There are 16 different types of hemagglutinin (H) which is the protein that allows the virus attach to the host. There are 9 types of neuraminidase (N) which is an enzyme that helps release new particles from infected cells. Water birds, those little bastards, have been found to carry viruses with all possible combinations of H and N. The famous Avian bird flu from 1997 in Hong Kong was an H5N1. Since then, this crazy bird flu has resurfaced in 2002 in southeast Asia.
As a general note, emerging viruses are generally NOT NEW; rather they are existing viruses that mutate, disseminate more widely in the current host species, or spread to new host species. Changes in host behavior or environmental changes can increase the viral traffic responsible for emerging disease. And this was the case with our recent swine flu. The source pigs were actually imported to Mexico from New Jersey. The reason they didn't infect humans in New Jersey is because of the differences in sanitation. The environmental change from being in sanitary conditions in New Jersey to unsanitary conditions in Mexico caused the virus to pass to humans. The rest my friends..... is history.
There are 3 types of influenza virus: types B and C, which only infect humans and have never caused an epidemic, and then there's our friend the type A which infects a wide range of animals, including (obviously) birds, pigs, horses, and humans. Influenza A strains have caused three major flu epidemics in history. The worst was the Spanish flu pandemic in 1918 which killed about 40 million people. Birds were the source of that one!
When the virus mutates as it's passed from one host species to another (i.e. bird to pig, etc.) it causes a likely scenario for a pandemic. When an animal is infected with more than one strain of flu virus, the different strains can undergo genetic recombination if the RNA molecules making up their genomes mix and match during viral assembly in the host. In more simple terms if there are different strains of the virus in a host, they have a big party and start combining to make one big bad virus. Along with mutation, this can lead to what causes these viruses to infect human cells. Since it's an animal virus, we haven't been exposed to that particular strain before so that means we lack immunity and the recombined virus (big bad virus) has the potential to be highly infections. Once it reaches humans, it begins to circulate among us because it can acquire the ability to spread from person to person which then leads to a major human outbreak. And since we all can't resist touching each other and people still don't listen when we say to wash your damn hands, we spread this big bad virus easily.
So what is exactly all this H1N1 coding anyway? Different strains of influenza A are given standardized names; for example the strain that caused the 1918 flu was also called H1N1. The name identifies which forms of two viral surface proteins are present: hemagglutinin (H) and neuraminidase (N). There are 16 different types of hemagglutinin (H) which is the protein that allows the virus attach to the host. There are 9 types of neuraminidase (N) which is an enzyme that helps release new particles from infected cells. Water birds, those little bastards, have been found to carry viruses with all possible combinations of H and N. The famous Avian bird flu from 1997 in Hong Kong was an H5N1. Since then, this crazy bird flu has resurfaced in 2002 in southeast Asia.
As a general note, emerging viruses are generally NOT NEW; rather they are existing viruses that mutate, disseminate more widely in the current host species, or spread to new host species. Changes in host behavior or environmental changes can increase the viral traffic responsible for emerging disease. And this was the case with our recent swine flu. The source pigs were actually imported to Mexico from New Jersey. The reason they didn't infect humans in New Jersey is because of the differences in sanitation. The environmental change from being in sanitary conditions in New Jersey to unsanitary conditions in Mexico caused the virus to pass to humans. The rest my friends..... is history.
