In Oaxaca, Mexico delegates from around the world gather (November 9-12) to discuss the global importance of biodiversity. Sponsored by the international science organization DIVERSITAS, the meeting brings together hundreds of experts from the natural and social sciences.

A dominant theme at the 4-day conference will be the interplay among humans, the environment and public health. DIVERSITAS organizer Peter Daszak calls biodiversity a kind of global health insurance. "If you really look at some of the big diseases that are affecting humans - diseases like SARS, avian influenza - there is something common to all of those," he says. "That is: changes to the environment are what drive them to emerge in the first place. Changes like building roads into forests, trading in wildlife species, changing the way we grow livestock around the world. Now if we look at that process and say 'let's start to address the way we cause these diseases to emerge,' we also do good for conservation. So there is a very interesting double positive benefit."

Researchers believe the bird flu virus first passed to humans in the crowded poultry markets of Vietnam, and is being spread by migratory birds.

Peter Daszak says SARS, the highly infectious respiratory illness that emerged in 2002, also began with the sale of wildlife ? in this case bats and wild civets in Chinese markets. Because the animals were kept in such close quarters a SARS-like virus in bats was able to move to the civets and from them to people. "What really needs to happen now is how do we use that information to protect us from SARS emerging again," he says, adding, "Quite interestingly these bats are being traded all across Asia for food. They are still being used for traditional medicine."

Mr. Daszak says one way public health officials can use that information is by paying closer attention to human-wildlife interaction. But he stresses that any regulation must be done thoughtfully, recognizing that wildlife also plays a positive role in the environment. For example, bats are integral to agriculture, he points out. "Fruit bats pollinate fruit trees. Bats eat insects, which are often agricultural pests and pollinate other crops as well. So bats perform a useful eco-service," he says. "And, one of the programs within DIVERSITAS is to look at the services to people that wildlife perform and to put a value on them and because of the value of those services we need to conserve these species."

DIVERSITAS organizer Peter Daszak expects the Mexico meeting to highlight new research and raise awareness about the delicate balance between wildlife conservation and human health. "If a virus comes from wildlife and we go out into the environment and exploit that species, we run the risk of the virus emerging," he says. "The big lesson is let's look at the way we interact with wildlife around the world, whether it is through hunting wildlife, [or] trading them internationally, we need to address how we do that and therefore prevent diseases emerging like SARS."

Peter Daszak says DIVERSITAS provides a forum for understanding the complex relationship between humans and the environment and the consequences of that interaction.