Pandemic Flu Viruses: An Old (And Formidable) Adversary

Has the H1N1 virus been around longer than previously suspected?

American and Hong Kong researchers now say yes. They have discovered connections between the different (but similar viruses) that have in the past wreaked havoc on populations unprepared for their onslaught.

Recent scientific discoveries represent an important milestone in understanding flu epidemics and are considered important because of the lack of studies of the virus in animals before the current outbreak of H1N1.

Researchers have discovered that the three worst pandemics of flu during the last century were actually circulating for years before they “struck.”

New knowledge suggests that the H1N1 virus that sparked the Spanish flu of 1918-1919 was not something novel. Previous studies suggested that the particular virus, which killed as many as 50 million people, was a mutant that jumped directly from birds to humans.

Now it is known that the virus circulated in both humans and swine well before the pandemic started and that it did not come directly from birds, but probably via genetic exchanges between flu viruses originating in both swine and humans.

We learn through our mistakes and nowhere is that fact more important or brought to light at a heavier price than in the area of scientific research. By understanding the natural history of viruses, current infections can be monitored and modified, thus reducing their impact on a vulnerable population.

The researchers responsible for this important discovery hail from the University of Hong Kong and St. Jude’s Hospital in the United States. Their findings, which involved two other pandemic viruses as well (Asian Flu of 1957 and H3N2 which caused the Hong Kong flu of 1968), have been published in the Proceedings of the National Academy of Sciences.

In the words of Guan Yi, microbiologist at the University of Hong Kong and member of the research team:

“The viruses of 1918 and 1957 went through at least two rounds of re-assortments before the pandemics occurred. Re-assortments happen when flu viruses swap genetic material, which happens when an animal or person is infected with two strains at the same time. Before, people did not know how pandemic viruses came about … this study gives us a deeper understanding into the evolution and emerging process of pandemic viruses.”

The focus of study concerned an analysis and comparison of the genes of the 1918, 1957, and 1968 viruses and their close relatives to determine their ancestry and the gene exchanges that created them.

Guan said:

“All three are different viruses but related … which would explain why some waves of the (1918-1919) pandemic were more deadly than others. The genes of the 1918 virus likely circulated in swine and humans from as early as 1911, and the virus was unlikely to have been transmitted directly from birds to humans.”

Although many questions remain concerning the direct involvement of swine in pandemic flu strains of the past, some have been answered and shed much light on the flu and its many perilous public health implications.

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