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Tracing the Start of the Bird FluThe start of the bird flu is difficult to trace. While many people consider it a recent occurrence, it may find its beginning laced back into history instead.
Several chickens died in Italy in 1878 as a result of what was termed as the fowl plague. Studies later determined that it was one of the influenza viruses. Recent studies of samples from victims of the 1918 Spanish flu lead scientists to believe that as well may have been a mutated form of bird flu that was able to be transmitted from one person to another. It is still difficult to say whether these cases have any bearing on the current variety of bird flu that is plaguing Asia.
In more recent history, the firs confirmed outbreak was in 1997 in Hong Kong. It is
the first confirmed case where the virus was found to be transmitted directly from birds to people, and 18 people were hospitalized with 6 deaths.
Six years later, in 2003, two new cases of H5N1 infections were diagnosed in Hong Kong. One patient recovered, and the other died. It was never determined how the people contacted the disease, nor were any additional cases reported in that area. Different strains of the avian flu not related to the H5N1 were also blamed for deaths and infections that year in China and Hong Kong. An outbreak of the virus among poultry in South Korea and Taiwan leads to a massive slaughter of infected birds.
In 2004, H5N1 was proven to be the cause of infection and death of 32 people in Thailand and Vietnam. Cases in domesticated poultry in these countries, as well as Japan, South Korea, Pakistan, Cambodia, Indonesia, South China, and Malaysia led to widespread slaughter of infected birds.
Since that time, the number of cases and deaths has been gradually increasing, as well as worldwide concern of the disease.
With such sporadic outbreaks of the disease, it has been difficult for scientists to determine an exact origin of the virus. Some scientists feel that genetic evidence points to the virus having been circulated in China for at least a decade, and being transmitted there to other countries via wild birds. The Chinese government denies these claims.
Research was done on 13,000 migratory birds and 50,000 market bird in southeast China between January 2004 and June 2005. From the birds purchased in the market, H5N1 was found in approximately 2% of apparently healthy animals. While different geographical areas had a slightly different genetic makeup, all could be traced from a 1996 Guangdong virus.
Researchers believe that this virus may be responsible for the viruses in Vietnam and Thailand, while Indonesia has its own related cluster of genetic matches. This information, however, conflicts with Chinese officials, who feel that the cases discovered were isolated and no proof that the virus originated in their country. However, finding these clusters also causes scientists to believe that the most likely form of transmission is through poultry movement and not wild birds.
Wild birds, however, may be responsible for infecting other wild birds, if not the local poultry populations. Tests of migratory birds in the Jiangxi province found variations of the virus that was very like the form found in Turkey. Many wild birds infected with the disease recover, allowing them to be carriers over great distances when they go through their annual migration patterns.
Regardless of the exact origins of the bird flu, the history of the virus is not nearly as important as what the future holds for it. By studying the history, scientists can hopefully get some clue as to how the virus works, so that they will better be able to come up with a vaccine to fight it.
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