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Human Pathogens: Their Presence and Prevalence
Dunn, R.R., Davies, T.J., Harris, N.C. and Gavin, M.C. Global drivers of human pathogen richness and prevalence. Proceedings of the Royal Society B 277: 2587-2595.

The authors write that "differences in the richness and prevalence of human pathogens among different geographical locations have ramifying consequences for societies and individuals," including human demographics (Anderson and May, 1991; WHO, 2004, 2008), human behavior (Fincher and Thornhill, 2008; Nettle, 2009; Park and Schaller, 2009; Preston et al., 2009; Zhu, 2009), the politics and political stability of countries (Thornhill et al., 2009), human fertility (Guegan et al., 2001), global economies (Thornhill et al., 2009) and, more generally, the course and dynamics of human history (Denevan, 1992; Morens et al., 2004). And in this regard, they note that "researchers have linked the presence and prevalence of some pathogens to climate, as has been highlighted in recent discussions of climate change and disease."

What was done
In an attempt to delve a little deeper into the subject of climate change and disease, and looking for some real-world answers, Dunn et al. conducted a global analysis of the relative influence of [1] climate, [2] alternative host diversity and [3] spending on disease prevention on modern patterns in the richness and prevalence of human pathogens.

What was learned
The Canadian, New Zealand and U.S. researchers determined that "pathogen richness (number of kinds) is largely explained by the number of birds and mammal species in a region," such that "the most diverse countries with respect to birds and mammals are also the most diverse with respect to pathogens." However -- and "importantly" -- they report that "for human health, the prevalence of key human pathogens (number of cases) is strongly influenced by disease control efforts."

What it means
As a consequence of their findings, Dunn et al. state that "even where disease richness is high, we might still control prevalence, particularly if we spend money in those regions where current spending is low, prevalence is high and populations are large." And, as they continue, "because pathogens are not restricted by political boundaries and local epidemics can rapidly transform into global pandemics, reducing prevalence in one part of the world will also benefit other parts of the world." Therefore, they conclude that "the degree to which these pathogens will affect us in the future depends on how well we mediate their prevalence." And pursuing the course of action they prescribe should be a whole lot easier, more practical, more timely, less expensive and more likely to be successful than trying to change the planet's temperature, as many climate alarmists contend we must do.

Anderson, R.M. and May, R.M. 1991. Infectious Diseases of Humans: Dynamics and Control. Oxford University Press, Oxford, United Kingdom.

Denevan, W. 1992. The pristine myth: the landscape of the Americas in 1492. Annals of the American Association of Geographers 82: 369-385.

Fincher, C.L. and Thornhill, R. 2008. Assortative sociality, limited dispersal, infectious disease and the genesis of the global pattern of religion diversity. Proceedings of the Royal Society B 275: 2587-2594.

Morens, D.M., Folkers, G.K. and Fauci, A.S. 2004. The challenge of emerging and re-emerging infectious diseases. Nature 430: 242-249.

Nettle, D. 2009. Ecological influences on human behavioural diversity: a review of recent findings. Trends in Ecology and Evolution 24: 618-624.

Park, J.H. and Schaller, M. 2009. Parasites, minds and cultures. Psychologist 22: 942-945.

Preston, B.T., Capellini, I., McNamara, P., Barton, R.A. and Nunn, C.L. 2009. Parasite resistance and the adaptive significance of sleep. BMC Evolutionary Biology 9: 10.1186/1471-2148-9-7.

Thornhill, R., Fincher, C.L. and Aran, D. 2009. Parasites, democratization, and the liberalization of values across contemporary countries. Biological Reviews 84: 113-131.

WHO. 2004. World Health Report 2004. World Health Organization, Geneva, Switzerland.

WHO. 2008. World Health Report 2008. World Health Organization, Geneva, Switzerland.

Zhu, S. 2009. Psychosis may be associated with toxoplasmosis. Medical Hypotheses 73: 799-801.

Reviewed 19 October 2011