Wednesday, September 2, 2009

Swine flu

Another cool find from the Registry of Noteworthy Research in Pathology - I just opened the Richard E. Shope folder which contains his original, handwritten research records documenting the first isolation of swine influenza. In an article from the Medical Tribune of June 17, 1963, Dr. Shope "described the appearance of a new respiratory disease among swine in the Midwestern states, in the autumn of 1918. Since there existed at that time a widespread outbreak of human pandemic influenza, and since the disease in swine, both clinically and at autopsy, resembled the human disease, it was named swine influenza." He said that swine flu was suspected to be as a result from an infection from humans, but because no virus from the human disease was yet available, it was impossible to make the connection.

But!! When the human influenza virus was discovered in 1933, it was found to be closely related to the swine virus, which supported the notion that swine flu originated in humans. So why did swine flu continue to appear once human flu more or less disappeared, at least as a pandemic, in about 1920? Dr. Shope maintained that the virus found a way to perpetuate itself in the hog population, which was ultimately proven when the swine lungworm, a nematode parasitic in the respiratory tract, was discovered. It serves as a reservoir and intermediate host, which is why the flu sticks around. If not for this reservoir, swine flu would have subsided about the same time as the human influenza virus.

Still with me? The article in the Medical Tribune, where I got all this information, is illustrated with a photo of Dr. Shope receiving the Ricketts Award from the son of Howard Taylor Ricketts, the doctor I wrote about yesterday, and for whom the award was named.

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