Impact of environmental factors on neglected emerging arboviral diseases

Abstract

BackgroundBrazil is a tropical country that is largely covered by rainforests and other natural ecosystems, which provide ideal conditions for the existence of many arboviruses. However, few analyses have examined the associations between environmental factors and arboviral diseases. Thus, based on the hypothesis of correlation between environment and epidemiology, the proposals of this study were (1) to obtain the probability of occurrence of Oropouche, Mayaro, Saint Louis and Rocio fevers in Brazil based on environmental conditions corresponding to the periods of occurrence of the outbreaks; (2) to describe the macroclimatic scenario in Brazil in the last 50 years, evaluating if there was any detectable tendency to increase temperatures and (3) to model future expansion of those arboviruses in Brazil based on future temperature projections.Methodology/Principal findingsOur model assessed seven environmental factors (annual rainfall, annual temperature, elevation, seasonality of temperature, seasonality of precipitation, thermal amplitude, and daytime temperature variation) for their association with the occurrence of outbreaks in the last 50 years. Our results suggest that various environmental factors distinctly influence the distribution of each arbovirus, with temperature being the central determinant of disease distribution in all high-risk areas. These areas are subject to change, since the average temperature of some areas has increased significantly over the time.Conclusions/SignificanceThis is the first spatio-temporal study of the Oropouche, Mayaro, Saint Louis, and Rocio arboviruses, and our results indicate that they may become increasingly important public health problems in Brazil. Thus, next studies and control programs should include these diseases and also take into consideration key environmental elements.

Vector competence of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus mosquitoes for Mayaro virus

“…Although there is still no evidence of the transmission efficiency of MAYV in an urban cycle, it has the potential to establish an epidemic scenario in the Americas, similar to what occurred with ZIKV and CHIKV [35]. Using mathematical models taking into account outbreaks since 1960 and increasing global temperature, Lorenz et al [36] predicted that MAYV would expand its area of coverage in the coming years. Thus, the importance of MAYV as a human pathogen with the potential to emerge in urban areas is strong.…”

Beyond diversity loss and climate change: Impacts of Amazon deforestation on infectious diseases and public health

“…Climate change resulting from deforestation of the Amazon rainforest and other tropical forests may favor the emergence of parasitic, fungal, viral and bacterial infections through the following basic mechanisms: first, by climate-derived ecological disturbances interfering with the maintenance of pathogens in their natural environments and hosts; second, by favoring the presence, distribution and proliferation of disease vectors in forest and urban areas, and third, by changes in temperature and rainfall patterns favoring pathogens' survival and reproduction and/or their ability to infect the human host. Changes in temperature also modify the ability of pathogens to infect vectors and to replicate in these animals (Patz et al 2000, Hales et al 2002, Vittor et al 2006, Barcellos et al 2009, Altizer et al 2013, Confalonieri et al 2014, Carvalho et al 2015, Flahault et al 2016, Samuel et al 2016, Wu et al 2016, Lorenz et al 2017, Nava et al 2017, Casadevall et al 2019, Duarte et al 2019a, Duarte & Giatti 2019, Khan et al 2019, Rao et al 2019. For example, if the average temperature of a given region increases, the spread of disease vectors, such as mosquitoes, could be favored, and this spread could lead to the colonization of new geographical areas previously inaccessible to these vectors.…”

Vector competence of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus mosquitoes for Mayaro virus

“…Using mathematical models taking into account outbreaks since 1960 and increasing global temperature, Lorenz et al ., 2017(32) predicted that MAYV would expand its area of coverage in the coming years. Thus, the importance of MAYV as a human pathogen with potential to emerge in urban areas is strong.…”