Environmental change and the dynamics of parasitic diseases in the Amazon

Abstract

The Amazonian environment is changing rapidly, due to deforestation, in the short term, and, climatic change is projected to alter its forest cover, in the next few decades. These modifications to the, environment have been altering the dynamics of infectious diseases which have natural foci in the, Amazonian biome, especially in its forest. Current land use practices which are changing the, epidemiological profile of the parasitic diseases in the region are road building; logging; mining; expansion of agriculture and cattle ranching and the building of large dams. Malaria and the cutaneous, leishmaniasis are the diseases best known for their rapid changes in response to environmental, modifications. Others such as soil-transmitted helminthiases, filarial infections and toxoplasmosis, which have part of their developmental cycles in the biophysical environment, are also expected to, change rapidly. An interdisciplinary approach and an integrated, international surveillance are needed, to manage the environmentally-driven changes in the Amazonian parasitic diseases in the near future.

Adaptative processes, control measures, genetic background, and resilience of malaria vectors and environmental changes in the Amazon region

“…Human activities in the Amazon biome that favor increased incidence of malaria are characterized by the occupation of urban and peri-urban spaces in an uncontrolled manner; the construction of hydroelectric power plants, irrigation projects, and fishponds; the exploitation of fossil fuels, minerals, and natural gas; forest fires; deforestation; and road construction (Tadei et al, 1988(Tadei et al, , 2002Confaloniere et al, 2014;Hahn et al, 2014). In addition to human activities, global environmental changes, such as variations in temperature, humidity, and rainfall (Campbell-Lendrum et al, 2015), can lead to the selection of resilient mosquito species with genetic adaptations for these new environmental conditions, thus enabling the selection of insects resistant to synthetic insecticides (Nkya et al, 2013;Glunt et al, 2014).…”

Reduced Leishmania (L.) infantum chagasi parasitic loads in humans exposed to Lutzomyia longipalpis bites in the Amazon region of Brazil

“…This possibility is re-enforced by the similar pattern observed for the prevalence of sand fly bite exposure, which indicates endemic transmission, showing higher prevalence in young children and low prevalence in old adults (Anderson and May, 1991;Calzada et al 2015), with a flat prevalence for age groups corresponding to the economically active population, which has a high proportion of migrants in our study area (Confalonieri et al 2014).…”

“…This scenario indicates endemic transmission, with higher prevalence in young children and low prevalence in old people, but the nearly constant prevalence in age groups corresponding to the economically active population, which in the area has a large proportion of 'economic' migrants, i.e. people who moved for jobs and now reside into the area permanently (Prothero, 1965;Wijeyaratne et al 1994;Confalonieri et al 2014).…”

Soroepidemiologia da infecção pelo Toxoplasma gondii no Município de Novo Repartimento, Estado do Pará, Brasil

“…Diante desse fato, observa-se claramente que a interface entre área urbana, rural e floresta nesse município é bem próxima. Essa situação acaba facilitando a infecção pelo T. gondii, devido ao contato, cada vez mais comum, entre o homem e animais domésticos com ambientes possivelmente contaminados com oocistos do parasito excretados por felinos presentes nessas diferentes áreas 21,31,32,33 . Como agravante, há ainda a possibilidade de circulação de cepas virulentas, até então restritas ao ambiente silvestre, mas que, com essa proximidade, em especial entre felinos, podem se adaptar ou sofrer recombinações genéticas com aquelas já em circulação nos ambientes urbano e rural, aumentando o risco de emergência de cepas mais virulentas e, consequentemente, a ocorrência de formas severas da doença 6,22 .…”