Environmental Change and the Emergence of Infectious Diseases: A Regional Perspective From South America

Background

The emergence of infectious diseases was identified as a major global health threat in the last quarter of the 20^th century. Zoonotic pathogens from wild animals formed the majority of newly emerged human pathogens in the past few decades (Jones et al., 2008). Several factors have been pointed as major contributors to human infectious disease emergence: new strains of the pathogens, increased resistance to antibiotics, reduced resistance of hosts (e.g. infection by HIV), variations in human populations densities, shifts in diversity of populations of vectors and hosts, hunting of wild animals for food, deforestation and loss of biodiversity and climatic anomalies (Jones et al. 2008; Keesing et al, 2010; Pongsiri et al, 2009; Wilcox & Gubler 2005).

In general, it is acknowledged that, for disease emergence to take place, an association of different drivers is necessary. In South America, since the middle of the last century, several diseases have emerged caused by different etiological agents, from Protozoa to viral infections. Some of these were part of larger epidemics/pandemics (e.g. Cholera; Dengue Fever) but other diseases have emerged as autochthonous local processes and became endemic, such as viral haemorrhagic fevers caused by Junin and Guanarito Viruses. While some of those that have emerged or re-emerged became widely distributed (e.g. Dengue Fever), others occurred as local outbreaks with a small number of cases, restricted in time, and no more cases were reported (e.g. Sabiá Virus infections).