Attempting to eradicate disease is not a good use of public health dollars, say researchers writing in Proceedings of The Royal Society B. Instead, the emphasis should be placed on reducing the prevalence of diseases in areas most affected by them.

What's more, the scientists argue, new research shows that the most at-risk populations can be identified using just three variables.

A great diversity of local mammals and birds in a region, a large human population and ineffective disease control efforts point to a high-prevalence of disease. Climate plays a role in determining how many different kinds of diseases there are, but not how many people will suffer from them.

Biology research shows general health spending offers far better return in most affected areas.

"Because disease is not restricted by political boundaries local epidemics can rapidly transform into global pandemics, reducing prevalence in one part of the world will also benefit people everywhere," explains McGill University Biologist Jonathan Davies. Recent flu outbreaks demonstrate how quickly diseases can spread to different parts of the world and the high cost of providing vaccines for millions of people. By targeting at-risk populations it might be possible to prevent global outbreaks and save money at the same time.

The research shows that efforts should be concentrated in countries with large populations, such as India and Pakistan, and areas where there is currently almost no spending on health care, such as Madagascar and much of eastern Africa.

In addition to the health benefits, the research team points out that disease affects human behavior, the politics and political stability of countries, human fertility, global economies and more generally the course and dynamics of human history. The ramifications could be huge. "While it is clear that the distribution of diseases have, in the past, affected all aspects of human life, the degree to which these diseases will affect us in the future depends on the choices we make today in the global allocation of health-care dollars," Davies said.

Citation: Dunn et al., Global drivers of human pathogen richness and prevalence', Proc. R. Soc. B, April 2010; doi:10.1098/rspb.2010.0340