Unpredictable Pandemics: Viruses Spread Between Humans and Animals

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H5N1 is also a concern for becoming a pandemic. Image by the CDC.

H5N1 is also a concern for becoming a pandemic. Image by the CDC.

Scientists are warning the public that ‘unpredictable pandemics’ are possible as viruses spread from animals to humans. The warning comes after a woman was diagnosed with the common strain of bird flu, H6N1 and after an article in The Lancet that talked about a need for “intensive” monitoring of bird flu.

Are we monitoring for these potential pandemics?

Bird Flu: The Lancet Article

An article published in The Lancet entitled, “Human infection with avian influenza A H6N1 virus: an epidemiological analysis” discusses the human infection of H6N1. The 20 year old woman who was diagnosed with H6N1 went to the hospital in May 2013 presenting with shortness of breath, where the throat swab came up with an unsubtyped  influenza A virus.

The hospital sent the sample to the Tawian Centers for Disease Control for further identification; the tests showed that the virus was H6N1, but they couldn’t identify the source of the infection. This is the first report of the wild avian influenza, H6N1 in humans. Researcher conclude that as these viruses continue to evolve and change, the more at risk humans are of catching these viruses and then passing them onto other humans. According to the researchers, “Our report highlights the continuous need for preparedness for a pandemic of unpredictable and complex avian influenza.”

Avian Influenza and Pandemics

No one knows when a pandemic will occur or what virus it may be; however, there has been quite the concern over the avian influenza.

Experts are also watching the H7N9 virus as a potential to becoming a pandemic.  Image by the CDC.

Experts are also watching the H7N9 virus as a potential to becoming a pandemic. Image by the CDC.

Avian influenza, or bird flu, are influenza A viruses, which only infect birds. However, there are genetic differences between subtypes that infect humans and birds and within these subtypes there are different strains. Experts categorizes avian influenza viruses into two groups, low pathogenic and high pathogenic.

According to the Centers for Disease Control and Prevention (CDC) most avian influenza is considered ‘low pathogenic’ because it causes mild illness in poultry. However, subtypes, H5 and H7, which include the H5N1, H7N7, H7N3 have been considered highly pathogenic because the human infection has ranged from mild infections to severe and fatal infections. H6N1 is considered a low pathogenic virus and only one human case (the woman in Taiwan) has been reported.

There are 16 different avian flu types, but the one that is of the most concern is H5N1. The first H5N1 cause occurred in 2003 and since then there have been 641 cases and 380 deaths in 15 different countries, reports the World Health Organization (WHO).

Other strains like the H7N9 is also becoming a concern. The first cases of H7N9 began in February 2013 in China and by April 2013 more cases had been identified in Shanghai, Anhui, Jiangsu, Zhejiang, Beijing, and Henan. According to the WHO, as of October 25, 2013 there have been a total of 137 cases and 45 deaths.

Researchers at Massachusetts Institute of Technology reported in the journal Cell  that if either the H5N9 or the H7N9 mutated and became easily passed from human to human, there would be a great risk of a pandemic. Researchers said that it would only take one or two mutations before bird flu would be easily passed between humans.

Pandemic Alert

According to the WHO, the main risk factor for human infections of avian influenza is having direct contact with sick poultry (dead or a live) and their contaminated environment. The WHO and animal health organizations are working together to identify and reduce animal infections and to reduce the public’s risk of developing avian influenza. According to the WHO, “an influenza pandemic occurs when key factors converge: an influenza virus emerges with the ability to cause sustained transmission from human-to-human, and there is very low, or no, immunity to the virus among most people.”

Resources:

BBC News. ‘Unpredictable Pandemic Warnings.’ (2013). Accessed November 14, 2013.

Center for Disease Control and Prevention. Avian Influenza A viruses. (2005). Accessed November 14, 2013.

Medical News Today. Influenza Virus Mutations Could Result In Pandemic Flu. (2013). Accessed November 14, 2013.

Wei, S., Yang, J., Wu, H., et al. Human infection with avian influenza A H6N1 virus: an epidemiological analysis. The Lancet. (2013). Accessed November 14, 2013.

World Health Organization. Cumulative number of confirmed human cases for avian influenza A(H5N1) reported to WHO, 2003-2013. Accessed November 14, 2103.

World Health Organization. Number of confirmed human cases of avian influenza A(H7N9) reported to WHO. Accessed November 14, 2013.

World Health Organization. Avian Influenza. (2011). Accessed November 14, 2013.

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