FAO sees threats from concentrated livestock operations.

The risk of disease transmission from animals to humans is predicted to increase in the future due to human and livestock population growth, dramatic changes in livestock production, the emergence of worldwide agro-food networks, and a significant increase in mobility of people and goods, according

"There is no doubt that the world has to depend upon some of the technologies of intensive animal food production systems," said FAO livestock policy expert Joachim Otte. "But excessive concentration of animals in large scale industrial production units should be avoided and adequate investments should be made in heightened biosecurity and improved disease monitoring to safeguard public health," he added.

To help combat the movement of diseases from animals to humans--and from animals to other animals--FAO is calling on meat producers to apply basic biosecurity measures. For example, the report said, production sites should not be built close to urban areas or wild bird populations; farms should be regularly cleaned and disinfected; the movements of staff and vehicles should be controlled and employees should be trained in biosecurity.

As the report notes, the demand for meat and other livestock products has increased substantially as the global human population has grown and countries have become more affluent. In response, there have been significant increases in livestock populations and densities, at times close to urban centers. In addition, concentrated industrial food animal production has increased, using fewer but more productive livestock breeds and lines, with vertical integration of the various stages of production, as well as major changes in the design and size of animal housing facilities. "These developments have potentially serious consequences for local and global disease risks, which, so far, have not been widely recognized," says the report.

Keeping thousands of animals in industrial-sized production units coupled with the often rapid and repeated movement of animals between units in the course of the production process increases the probability of transferring pathogens within and between livestock populations, says the report. The frequency of exposure of susceptible animal populations to pathogens also affects the rates of pathogen evolution, and thus could facilitate the emergence of pathogens.

The report concludes that policy makers in both developing and developed countries appear to accept that large-scale industrial farms have must develop higher standards. "But the realities of animal health, economic incentives and the public interest in disease prevention are far too complex for simple rules of thumb like this to be optimal for society," it says. "Only a comprehensive, evidence-based approach to risk management on industrial and backyard farms can sustain a safe and affordable food supply."