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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: This comment is mainly concerned with the effects of Ebola but I think that it is an interesting subject. In this paper that I found they mention that the Ebola haemorrhagic fever has contributed to the roughly 98% local population decline of the great apes http://www.scielo.org.za/scielo.php?pid=S0030-24652012000200003&script=sci_arttext. I wonder how that has affected the biodiversity in those areas? It would be interesting to see if there were any historical records of the biodiversity before EHF hit those areas and how the community dynamics have changed.
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      Jun 3 2013: I thought the piece from "Spillover" was very interesting, regarding Ebola and the severity with which it can curtail ape populations. I did not even know that Ebola was zoonotic until that reading. Just hearing about researchers being unable to find a single sign of gorillas in prime gorilla habitat in an area where they used to thrive, or finding the normally trafficked Bais completely bereft of gorillas, and the very very few found could not even be approached is quite illustrative. Also the clusters, or "piles" of apes fallen dead in the jungle was a really haunting image, and captures the speed with which an Ebola outbreak can ravage these apes. 98%, damn.

      It would/will be interesting to see which species starts filling the niche of the extirpated apes, maybe even just other apes immigrating in, or a reestablishment of local populations from resistant survivors/uninfected refugees. In any case, that's a huge ecological event, losing practically all of a large-bodied animal, quickly.
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        Jun 3 2013: That is exactly what I was wondering. How would the large animal niche be filled and how do the plant communities change?
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          Jun 3 2013: Nick, you might like this article about seed dispersal by lowland gorillas. It discusses how their nesting sites might benefit seed survival because they are usually in more open areas, that allow for more light availability. Its a little long, but most of the good stuff is in the discussion section.
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          Jun 4 2013: Sometimes the niche won't be filled by another large animal. Often times smaller animals are able to exploit the niche left behind by the disappearance of a large animals. But large rainforest animals such as primates don't necessarily have other animals that occupy that same niche (outside of other primates). If chimps or gorillas are wiped out from a forested area because of disease, it's very hard to replace those animals and their ecological impact.
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        Jun 3 2013: Sometimes I wonder if it would even be possible to 're-fill' any empty niches left by extirpation of great apes and other large primates with other populations of the same species. So many of those species are already limited to small and scatted populations and they need so much space to thrive. And of course, primates are not a very specious group in the first place.
        I have a horrible feeling that we could see the extinction of a great ape species in our lifetimes.
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          Jun 3 2013: Unfortunately, I think your horrible feeling might be right. I've heard predictions that chimpanzees, our closest relatives, might be extinct in 30 years!!!!!!!

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