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Christine O'Connor

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Can we control the emergence of zoonotic infectious disease?

Seventy five percent of the world’s emerging infectious diseases are zoonotic, or animal, in origin. Familiar examples include HIV/AIDS, Ebola, SARS, Lyme disease and West Nile Virus.

Humans play a big part in the emergence and spread of these and other infectious diseases. Our ever-expanding encroachment on forests – due to deforestation and increases in bushmeat hunting – increases the potential for disease transmission from animals to humans. Urbanization and global travel more easily allow for the spread of a disease from person to person and across the globe. These factors combine to greatly increase the probability of successful emergence and spread of an infectious disease.

Despite the clear importance understanding and controlling zoonotic diseases we have not had much success eradicating them, or even limiting their spread. It is hard to eradicate what we can’t find. Fore example, despite many years of study, researchers still are not sure where Ebola comes from. Outbreaks can be traced to handling of dead chimpanzees and gorillas, but neither appears to be the reservoir host (a species that is a source of infection but not affected by the disease) for Ebola.

What should be done to stop or control the emergence and spread of these diseases before they become global pandemics? Should we try and limit close contact with wild animals, perhaps via habitat preservation? Should we better control the bushmeat trade and/or educate hunters and consumers of bushmeat and other types of wild animal markets of the risks involved with such meat? Or, is a more proactive approach possible? Is there a way to pre-emptively identify such emerging diseases, via monitoring of wild animals and those who regularly have close contact with them?

Souce: Spillover by David Quammen

Also see: Q&A on swine flue with virus hunter Nathan Wolfe "We've created the perfect storm for viruses" http://blog.ted.com/2009/04/28/qa_with_virus_h/


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    Jun 3 2013: How do the effects of climate change factor in to zoonotic disease spread? When the vectors for disease can range farther or into new areas, the likelihood of transmission increases. Maybe it is not just increased contact with animals in their historic ranges but also their spread into previously marginal habitat that contributes to increased disease transmission. There was an article in Veterinary World 2010 entitled "Effect of climatic changes on the prevalence of zoonotic diseases" that explores some of these issues. http://www.scopemed.org/?mno=2164
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      Jun 3 2013: Climate change will almost certainly affect the spread of zoonotic infectious diseases. Unfortunately, scientists are not sure how - depending on the animals affected, disease transmission mode, original range etc., the probability of disease spread could increase or decrease. (For a possible increase, see this article about Denge fever re-emergence in the south from Slate: http://www.slate.com/articles/health_and_science/pandemics/2012/12/dengue_fever_in_united_states_breakbone_fever_outbreaks_florida_texas_and.html

      However, on a possible bright side, the transmission of some infectious diseases can be controlled, but widespread control and elimination seems to depend on organization and effort from the government. As shown by this article from the CDC most of the US used to be endemic for malaria, and now I don't think anywhere is.
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        Jun 4 2013: These articles give me mixed emotions. I think it is great that we were able to rid the US of malaria, but I'm not sure that spraying DDT on the interior of homes is a healthy solution. I was surprised to learn that dengue has had such a presence here, but if its only a matter of time before it re-establishes itself, I wonder if we will be facing lots of large scale insecticide dispersals in the future?...I'm picturing "Silent Spring" all over again

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