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The highly pathogenic influenza A virus subtype H5N1 is an emerging avian influenza virus that has been causing global concern as a potential pandemic threat. It is often referred to simply as "bird flu" or "avian influenza", even though it is only one subtype of avian influenza-causing virus.
H5N1 has killed millions of poultry in a growing number of countries throughout Asia, Europe and Africa. Health experts are concerned that the coexistence of human flu viruses and avian flu viruses (especially H5N1) will provide an opportunity for genetic material to be exchanged between species-specific viruses, possibly creating a new virulent influenza strain that is easily transmissible and lethal to humans. The mortality rate for humans with H5N1 is 60%.
Since the first H5N1 outbreak occurred in 1987, there has been an increasing number of HPAI H5N1 bird-to-human transmissions, leading to clinically severe and fatal human infections. Because a significant species barrier exists between birds and humans, though, the virus does not easily cross over to humans, though some cases of infection are being researched to discern whether human to human transmission is occurring. More research is necessary to understand the pathogenesis and epidemiology of the H5N1 virus in humans. Exposure routes and other disease transmission characteristics, such as genetic and immunological factors that may increase the likelihood of infection, are not clearly understood.
On January 18, 2009, a 27-year-old woman from eastern China died of bird flu, Chinese authorities said, making her the second person to die from the deadly virus at that time. Two tests on the woman were positive for H5N1 avian influenza, said the ministry, which did not say how she might have contracted the virus.
Although millions of birds have become infected with the virus since its discovery, 359 humans have died from the H5N1 in twelve countries according to WHO data as of August 10, 2012.
The avian flu claimed at least 300 humans in Azerbaijan, Cambodia, China, Egypt, Indonesia, Iraq, Laos, Nigeria, Pakistan, Thailand, Turkey, and Vietnam. Epidemiologists are afraid the next time such a virus mutates, it could pass from human to human; however, the current A/H5N1 virus does not transmit easily from human to human. If this form of transmission occurs, another pandemic could result. Thus, disease-control centers around the world are making avian flu a top priority. These organizations encourage poultry-related operations to develop a preemptive plan to prevent the spread of H5N1 and its potentially pandemic strains. The recommended plans center on providing protective clothing for workers and isolating flocks to prevent the spread of the virus.
The Thailand outbreak of avian flu caused massive economic losses, especially among poultry workers. Infected birds were culled and slaughtered. The public lost confidence with the poultry products, thus decreasing the consumption of chicken products. This also elicited a ban from importing countries. There were, however, factors which aggravated the spread of the virus, including bird migration, cool temperature (increases virus survival) and several festivals at that time.
Read more about this topic: Avian Influenza