ZOONOSES: BLURRED LINES OF EMERGENT DISEASE AND ECOSYSTEM HEALTH


Zoonoses: Blurred Lines of Emergent Disease and Ecosystem Health


Emerging and neglected zoonotic diseases


The 20th century was a period of unprecedented ecological change, with dramatic reductions in natural ecosystems and biodiversity and equally dramatic increases in people and domestic animals. Never before have so many animals been kept by so many people—and never before have so many opportunities existed for pathogens to pass from wild and domestic animals through the biophysical environment to affect people causing zoonotic diseases or zoonoses. The result has been a worldwide increase in emerging zoonotic diseases, outbreaks of epidemic zoonoses as well as a rise in foodborne zoonoses globally, and a troubling persistence of neglected zoonotic diseases in poor countries.


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Around 60 per cent of all infectious diseases in humans are zoonotic1


as are 75 per cent of all emerging infectious diseases.2


On average, one new infectious disease emerges in humans every four months.3


While many originate in wildlife, livestock


often serve as an epidemiological bridge between wildlife and human infections. This is especially the case for intensively- reared livestock which are often genetically similar within a herd or flock and therefore lack the genetic diversity that provides resilience: the result of being bred for production characteristics rather than disease resistance.4


An example of livestock acting


as a “disease bridge” is the case of bird flu or avian influenza pathogens, which first circulated in wild birds, then infected domestic poultry and from them passed to humans. The


Photo Credit: ILRI/ Nguyen Ngoc Huyen

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