About viruses and viral disease
5 February 2013
I think, to make the title and content more accurate, it would be good to show how many of the infections turned eventually to AIDS.
I certainly do after reading “Possible consequences of the overlap between the CaMV 35S promoter regions in plant transformation vectors used and the viral gene VI in transgenic plants” by Nancy Podevin and Patrick du Jardin. From GM Crops and Food: Biotechnology in Agriculture and the Food Chain 3:4, 296-300; October/November/December 2012; Landes Bioscience
I can imagine how attractive the concept of the “patient zero” must be from an epidemiological point of view since it brings at least some simplification to an otherwise very complex discipline. However, do you think it is really a valid concept for most viral diseases/zoonoses or just an oversimplification?
The slide simplifies the origin of HIV-1 group M viruses. All evidence indicates that this lineage arose from a very small number of cross-species transmissions from chimanzee to human. Although we will never know for sure the number of such initial transmissions, current evidence suggests that in the early 1900s probably less than ten individuals, possibly one, were infected with HIV-cpz. Bear in mind that each of the other HIV-1 clades also represent a separate spillover event. It seems likely that HIV-cpz infected small numbers of humans for a long time, and only those in the early 1900s continued further in humans – probably as a consequence of the colonialization of Africa in the 1900s. I find it mind boggling that one or a few crossovers lead to so many human infections. The insidious nature of the infection for so many years is truly remarkable.
The other point I wanted to make is that flight attendant Gaetan Dugas was not patient zero – not by a long shot.
David Quammen has an excellent chapter in Spillover providing a nice story to accompany this figure. Well worth a read for anyone interested.
Because chimpanzees and cauliflower are both so similar to humans, and because we haven’t already been eating functional CaMV promoters for millennia? Way to stay on topic.
The aforementioned Sharp and Hahn paper, figure 1 is really good to show all the HIV clades’ origins. Seeing this blog post immediately made me think of that figure (1). Therefor at the very least 4 patient zeroes. I feel that picture is a good way to dispel a lot of HIV myths/conspiracy theories.
Anyone else notice the chimp is holding a plastic gun to his own mouth? Yikes! Given the debates going on currently…
Has anyone else seen Ian Lipkin’s TED talk where he puts together a model showing the regular introduction of viruses from other primates into the human population? He suggests that viruses are always “testing the waters” and that there might be several unsuccessful introductions. This could mean there were lots of patient zeroes, but only four that led to productive infections and spawned the pandemic.
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