Biodiversity loss isn’t just bad for the species that go extinct – it can also lead to major increases in human disease. That’s the message from ecologists at the ESA meeting, who are today calling for greater awareness of the often complex link between ecosystem harm and human health.

Damage to ecosystems can contribute to human disease in three main ways, says Osvaldo Sala of Brown University, one of the ecologists spearheading the campaign. Species loss can wipe out many plant species of medicinal value; it can reduce ecosystems’ ability to regulate the buildup of toxic compounds in food and water; and it can increase the spread of infectious disease by cutting the number of alternative host species besides humans.

That process is illustrated by the rise in malaria in Peru as a result of human development. Jonathan Patz of the University of Wisconsin-Madison has discovered that, since the construction of a new road through the Peruvian Amazon in the 1980s, the malaria-carrying mosquito Anopheles darlingi has risen to prominence, bringing with it a severe increase in disease. Previously, this mosquito was hardly present at all, and in its meteoric rise it has outcompeted more than 400 other mosquito species, most of them harmless to humans.

The problem, as with many in the complex world of ecology, is that it’s difficult to know how to begin to tackle the problem in a concrete way. With so many variables at play, changing one thing could have unforseen knock-on consequences elsewhere. The Peruvian region that Patz studied, for example, was already colonized by humans, but it was the construction of the road that seemed to boost the mosquitoes. It’s not really clear why.

In a bid to form a coherent plan of action, Patz and his colleagues have organized a the first ever ‘ecohealth’ conference, to be held in Madison in October. The problem extends beyond simple direct increases in disease-related organisms such as mosquitoes. In some cases, for instance where overapplication of nitrogen fertilizer leads to unexpected booms in ecosystem growth that can fuel disease-causing microbes, the picture is so complex as to be almost intractable without a lot of detailed study.

Often, the solution will involve the efforts of scientists who do not have much prior experience of thinking about human disease. “I came to this as a biogeochemist,” says Alan Townsend of the University of Colorado. “But we are starting to see that the nitrogen cycle not only has a litany of environmental effects, but also there’s a lot of smoke and fire to indicate that it affects human health.”