The text is from the article "Forests and emerging infectious diseases of humans", 2006 by B.A. Wilcox and B. Ellis, published in Unasylva No. 224, Vol. 57, 2006/2 The whole article
"With the interweaving of forests, pathogens and the development of human civilization, deforestation and other land use changes have an important part in the emergence of disease. Infectious diseases have always been an important part of human life. They have significantly influenced human biology and society, even determining the course of major historical events. The first plague-causing pathogens such as smallpox are believed to have originated in tropical Asia early in the history of animal husbandry and large-scale forest clearing for permanent cropland and human settlements. Crowding and the mixing of people, domestic animals and wildlife, along with a warm humid climate, were as ideal for pathogen evolution, survival and transmission several millennia ago as they are now.
The concept of emerging infectious diseases (EIDs) was prompted by the appearance of novel pathogens such as human immunodeficiency virus (HIV) and Ebola virus; the evolution of more virulent or drug-resistant pathogenic variants of known microbes; and the geographic expansion and increasing epidemic outbreaks of the diseases caused by these pathogens as well as older diseases such as malaria and dengue. More recently, the concept was reinforced by the dramatic outbreak of severe acute respiratory syndrome (SARS) virus.
The recent upsurge in infectious diseases, which began to attract the attention of the World Health Organization (WHO) and leading national health agencies in the 1980s, is often attributed to the dramatic increase in human population size and mobility, as well as social and environmental changes since the Second World War. Actually, such transitions have caused major upsurges in infectious diseases at the regional level since antiquity. The most notable difference today is the speed, scale and global dimension of the transition, and its occurrence in the era of modern biomedicine and public health programmes. Overconfidence in the former and inadequate deployment of the latter are major contributors to the EID problem, especially in the tropical developing regions.
An increasing number of studies on EIDs point to changes in land cover and land use, including forest cover change (particularly deforestation and forest fragmentation) along with urbanization and agricultural intensification, as major factors contributing to the surge in infectious diseases. Indeed the current increase coincides with accelerating rates of tropical deforestation in the past several decades. Today, both deforestation and emerging infectious diseases remain largely associated with tropical regions but have impacts that extend globally. Both are similarly intertwined with issues of economic development, land use and governance, requiring cross-sectoral solutions."