genetically similar stock kept close together. Thus the animals are not only exposed to more contact opportunities but they also lack the genetic diversity that helps resist the spread of disease, a vulnerability known as the monoculture effect. Intensification of livestock production systems also results in increased fertiliser use (for feed and fodder) and increased production of livestock waste, which can create nutrient- rich environments that foster certain pathogens.23
Changes
in human host behaviours are also drivers of emerging zoonotic disease, including travel, conflict, migration, wildlife trade, globalization, urbanization, and changing dietary preferences.24
Changes in the pathogens themselves occur as they evolve to exploit new hosts or adapt to changing evolutionary pressures. An example of this is the emergence of resistance to antimicrobial drugs.25
Antimicrobial resistance is the result of
Primary drivers of disease emergence associated with the past emerging zoonotic disease events
Incidences of spill-over of zoonotic diseases due to anthropogenic activities
Rabies transmitted by
Forest fragmentation in North America led to an increased risk of
Lyme Disease in human
vampire bats to cattle and human was linked to forest activities in South America
Emergence of
Bat-associated viruses emerged due to loss of bat habitat from deforestation and agricultural expansion
Nipah virus was linked to intensification
of pig farming and fruit production in Malaysia
Source: Kalema-Zikusoka (2005)45 Video: Zoonotic Diseases Among Pastoralists in Uganda
pathogens being exposed to antimicrobial drugs and building resistance over their short-lived generations. This most commonly occurs when people are prescribed antimicrobials or buy them without prescription and self-treat incorrectly. Antimicrobials are also widely used, or misused, in veterinary medicine, often as preventatives, and resistance to them is growing in domesticated animals especially in industrial- style production systems.26
Antimicrobial resistance created
in livestock can then affect humans, so when people get sick antibiotics no longer work.
Suspected disease transmission from people to primates
Scabies and measles in mountain gorillas at Bwindi Impenetrable
National Park, Uganda, and Parc de Volcans, Rwanda
Yaws and intestinal parasites in baboons at Gombe National Park, Tanzania
Polio in Chimpanzees at Gombe National
Park Tanzania, and in Beni, Congo
Japanese
encephalitis virus (JEV) was linked to
irrigated rice production and pig farming in Southeast Asia
Ebola outbreak in West Africa was
a result of forest losses, leading to closer
contacts between wildlife and
human settlements Emergence
of Avian Influenza was linked to
intensive poultry farming
Early human cases of SARS was associated with contact with civet cats either in the wild or in live animal markets
Created based on data from Jones et al. (2013)5
© IDRC/Government of Canada
Video Link:
https://www.youtube.com/watch?v=fp4BhQTNjwQ Photo Credit: ILRI/ Stevie Mann
23
UNEP FRONTIERS 2016 REPORT
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