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Three in Five Human Diseases Have Animal Links

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When it comes to human health, we're not the only species out there.

In fact, of the roughly 1,500 diseases now recognized in humans, about 60 percent are due to pathogens that move across species. Such were the findings of a task force convened through the American Veterinary Medical Association with the backing of Ronald Davis, the immediate past president of the American Medical Association.

The AVMA's immediate past president Roger Mahr and Davis are the powers behind the One Health Initiative that reported on in February.

The task force, composed of leaders in human and animal health, public health, the environment, government and industry, drafted 12 recommendations aimed at establishing the framework for One Health, which they say will involve multiple disciplines working together "to attain optimal health for people, animals and our environment."

The idea is to foster collaboration between physicians, veterinarians and other health professionals to addresses global health and environmental challenges.

You and your dog may have share many health ailments - arthritis, diabetes, heart disease - and collaboration between physicians and veterinarians is central to the concept. But the initiative goes far beyond that to consider global transmission of disease and the solving of interrelated health and environment quandaries.

A main impetus behind the initiative is the rapid emergence of zoonotic diseases (diseases that can be transmitted from animals to humans), as well as a global environment where many factors are increasing the spread of disease. Some of the factors listed in the report are: adaptation of microbes, increasing global travel, host susceptibility, climate change, poverty and social inequality.

These manmade factors, the writers say, have produced a "global mixing bowl" where "microbes have great possibilities to create new niches, cross species boundaries, travel worldwide very quickly and establish new beachheads in populations of people and animals while also invading environments where they are being uniquely maintained in nature outside of living hosts."

Scary stuff.

One example of how the One Health concept has worked is illustrated in a study of the 2006 outbreak of E. coli in 26 states. The bug was linked to contaminated fresh spinach grown in California. An investigation revealed that the same causative organism was found in cattle close to where the spinach was produced. This exact strain also was recovered from wild hogs that ran through the same fields.

The study found that ground and surface water in the agricultural region where the spinach was grown had been mixed due, in part, to old, porous agricultural wells and also to an irritation system that could not keep up with agricultural production. The investigation concluded that the spinach was likely contaminated by the irrigation water that contained E. coli from the infected hogs.

It is this sort of analysis - involving species within a total environment - that the One Health Initiative hopes to provide to a world that gets smaller by the day.