The new study found that increased biodiversity -- measured as the number of species and amount of forested land -- was not associated with reduced levels of infectious disease. In some cases, disease burdens actually increased as areas became more forested over time.

Surprisingly, Wood said, the study also found that increasing urbanization reduced disease, probably because cities bring people closer to medical care and give them greater access to vaccinations, clean water and sanitation. Even though cities crowd people together, the net benefit of their services results in reductions of infectious disease. It seems pretty clear that urbanization is good for people's health -- at least when it comes to infectious disease. And that's good news, because the world is rapidly urbanizing,  Wood said. The researchers relied on the UW-based Institute for Health Metrics and Evaluation's Global Burden of Disease database, a massive, worldwide effort to document premature death and disability from hundreds of diseases and injuries from 1990 to the present.

For example, as rates of precipitation went up, so did the burden of "geohelminths" -- a group of gut parasites that includes hookworm, whipworm and roundworm. Together, the geohelminths affect 1.5 billion people.

The authors hope the disease-specific information included in this study reveals pathways toward effective control, and helps country officials to avoid inadvertently exacerbating existing public health problems.

I hope this study encourages people to explicitly acknowledge the potential disease-related risks and benefits of conservation projects, Wood said.  The absolute last thing we want to do is a conservation project that gets people sick.

Regards
Alpine
Editorial Assistant
Journal of infectious disease and dignosis