The rising tide of ocean plagues: How humans are changing the dynamics of disease

A leading group of epidemiologists, veterinarians and ecologists report that humans are affecting the oceans in ways that are changing the dynamics of disease. Previously harmless pathogens are becoming killers when combined with contaminants; "good" parasites that invisibly control the balance of species in an ecosystem are disappearing; and changes in sea surface temperature can trigger cholera outbreaks thousands of miles away.

"Human activities are knocking things out of balance," says Andrew Dobson of Princeton University. "For some pathogens, we're seeing nasty synergistic effects with contaminants, such as PCBs. Paradoxically, diseases also play an important role in healthy ecosystem functioning. These changes tend to slip under the radar screen until they show up in ecological cascades that lead to wildlife and human health problems."