Bird Flu Outbreak in China: H5N1 Influenza Pandemic Fears Surge


Home / Bird Flu Outbreak in China: H5N1 Influenza Pandemic Fears Surge

How H5N1 Spreads Among Birds

H5N1 virus. Photo by Cynthia Goldsmith; CDC

The growing fear is that the H5N1 will mutate and be transmitted through person to person contact. Influenza is a virus, and viruses cannot produce on their own – they must infect a cell, and use the resources of that cell to reproduce. Viruses are classified into two groups: ribonucleic acid (RNA) and deoxyribonucleic acid (DNA), but all influenzas are RNA viruses. Influenza also comes in two viruses; A and B – influenza A viruses are found in animals, and influenza B is found among humans. Influenza B doesn’t make humans as sick as the influenza A virus. Ducks are the main carriers of the avian flu, because the duck’s proteases (type of molecule) are not affected by the avian flu – this means that ducks can carry the virus, without dying from it. Other fowl pass the virus along through sneezing, coughing, and contact with other infected birds.

How Could Bird Flu Spread to Humans?

There are two ways for the virus to mutate to humans, according to the World Health Organization (WHO). The first way is called a “reassortment event.” This event occurs when the H5N1 genetic material is transmitted to humans during a co-infection of a human or pig. This type of event would result in a significant amount of cases, and allows the virus to be transmitted quickly. The second way that the H5N1 can mutate is called adaptive mutation. Adaptive mutation occurs gradually – after multiple infections, the infected cells increase and the virus begins to spread. This results in a small cluster of infected people and human to human transmission.

H5N1 Vaccine

As of now there is no avian influenza vaccine for humans, but the CDC and WHO are working together to establish, and improve upon, best practices for bird flu treatment in human patients. With such high fatality rates when it does occur, it’s no wonder that the world holds its breath every time there’s even a minor outbreak of bird flu.


AFP. China reports bird flu outbreak. (2012). Accessed April 18, 2012.

World Health Organization. Cumulative number of confirmed human cases for avian influenza reported to WHO, 2003 to 2012. (2012). Accessed April 18, 2012. H5N1 Avian Flu. (2012). Accessed April 18, 2012.

World Health Organization. Avian Influenza Fact Sheet. (2011). Accessed April 18, 2012.

The New England Journal of Medicine. Avian Influenza (H5N1) Infection in Humans. (2005). Vol. 353: 1374-1385. 29. Accessed April 18, 2012.

Article updated 4-20-2012 for clarification of the difference between H5N1 in birds and H5N1 in humans.

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