POPULATION growth, agricultural expansion and the rise of globe-spanning food supply chains have dramatically altered how diseases emerge, jump species boundaries and spread, according to a report the U.N. Food & Agriculture Organization (FAO) released Dec. 16.
A new, more holistic approach to managing disease threats at the animal/human/environment interface is needed, FAO argued.
Of the new diseases that have emerged in people over recent decades, 70% are of animal origin and, in part, are directly related to the human quest for more animal-sourced food, according to the report, "World Livestock 2013: Changing Disease Landscapes."
The ongoing expansion of agricultural lands into wild areas, coupled with a worldwide boom in livestock production, means that "livestock and wildlife are more in contact with each other, and we, ourselves, are more in contact with animals than ever before," said Ren Wang, FAO assistant director-general for agriculture and consumer protection.
"What this means is that we cannot deal with human health, animal health and ecosystem health in isolation from each other; we have to look at them together and address the drivers of disease emergence, persistence and spread rather than simply fighting back against diseases after they emerge," he added.
FAO said its report provides a number of compelling reasons for taking a new tack on disease emergence.
Developing countries face a staggering burden of human, zoonotic and livestock diseases, the report says, creating a major impediment to development and food safety. Recurrent epidemics in livestock affect food security, livelihoods and national and local economies in poor and rich countries alike.
Meanwhile, food safety hazards and antibiotic resistance are on the increase worldwide, FAO said, adding that globalization and climate change are redistributing pathogens, vectors and hosts, and pandemic risks to humans caused by pathogens of animal origin present a major concern.
Role of livestock
FAO's report focuses, in particular, on how changes in the way people raise and trade animals have affected how diseases emerge and spread.
"In response to human population growth, income increases and urbanization, world food and agriculture has shifted its main focus from the supply of cereals as staples to providing an increasingly protein-rich diet based on livestock and fishery products," the report notes.
While livestock production provides a number of economic and nutritional benefits, the sector's rapid growth has spawned a number of health-related challenges, it says.
The risk of animal-to-human pathogen shifts varies greatly according to the type of livestock production and the presence of basic infrastructure and services.
While intensive production systems are largely free from high-impact animal and zoonotic diseases, they do present some pitfalls, particularly in developing countries and countries in transition, according to the report.
In intensive, large-scale production, strong biosecurity and health protection regimes generally prevent infectious disease problems, but major outbreaks occasionally occur when a pathogen performs a virulence jump, escapes the vaccine used, acquires resistance to antibiotics or travels along the food chain.
However, the report also states that disease emergence in livestock is not specific to large-scale, intensive systems.
Smallholder livestock systems — which tend to involve animals roaming freely over large areas, but still in relatively high densities — often facilitate disease spread both among local animal populations and over broad distances.
"The many diverse disease challenges discussed in this publication require greater attention to prevention," FAO argued. "A business-as-usual approach to risk management no longer suffices."
To achieve this, FAO advocates the "One Health" approach — looking at the interplay among environmental factors, animal health and human health and bringing together human health professionals, veterinary specialists, sociologists, economists and ecologists to work on disease issues within a holistic framework.
At the same time, "livestock health is the weakest link in our global health chain. Disease must be addressed at its source — particularly in animals," it adds.
FAO's report identifies four main fronts for action:
1. Reducing poverty-driven endemic disease burdens in humans and livestock;
2. Addressing the biological threats driven by globalization and climate change;
3. Providing safer animal-sourced food from healthy livestock and agriculture, and
4. Preventing disease agents from jumping from wildlife to domesticated animals and humans.
In particular, FAO said assembling better evidence on the drivers of animal disease must be a top priority, and the resulting analyses must focus attention on improving risk assessment and prevention measures.
There is a need for stronger mechanisms for the international exchange of information on animal diseases in general, as well as on best practices in livestock rearing and managing animal health risks, within a One Health framework, FAO concluded.