Mis à jour : avr. 19
Outbreaks of infectious diseases are more likely in areas of deforestation and monoculture, according to a study that suggests epidemics are likely to increase as biodiversity declines.
Land-use change is an important factor in the emergence of zoonotic viruses such as Covid-19 and vector-borne diseases such as malaria, the journal said, published Wednesday in Frontiers in Veterinary Science.
Even tree planting can increase health risks to local human populations if it focuses too narrowly on a small number of species, as is often the case in commercial forests, according to the research. In a holy ecosystem, diseases are filtered and blocked by a range of processes in a healthy, biodiversity-rich forest. When this is replaced by a plantation of palm trees, fields of soybeans or blocks of eucalyptus, some species essential to this balance die off, leaving the most harmful ones such as rats and mosquitoes to grow and spread pathogens throughout. human and non-human habitats. The net result is a loss of natural disease regulation.
The researchers examined the correlation between trends in forest areas, plantations, population and diseases around the world using statistics from international institutions such as the World Health Organization, the World Bank, the United Nations. for Food and Agriculture and the Gideon Epidemic Database. During the study period from 1990 to 2016, this covered 3884 foci of 116 zoonotic diseases that crossed the species barrier and 1996 foci of 69 vector-borne infectious diseases, mainly transmitted by mosquitoes, ticks or flies.
The document shows that epidemics increased over time, while plantations grew rapidly and overall forest cover gradually declined. By itself, a correlation is not evidence of causation as other factors may be involved, such as climatic disturbances. The authors strengthen their argument with multiple references to individual case studies that highlight the links between epidemics and land-use change.
In Brazil, scientists have shown that deforestation increases the risk of malaria outbreaks. In Southeast Asia, studies have shown how forest clearing promotes the Anopheles darlingi mosquito, which is the vector of several diseases. The loss of primary forests has also been identified as a factor in the emergence of Ebola in West Africa and the re-emergence of leishmaniasis transmitted by arthropods.
The new study adds to a growing body of evidence that viruses are more likely to spread to humans or animals if they live in or near human-disturbed ecosystems, such as recently cleared forests or swamps drained for agricultural land, mining projects or residential projects.
This is shaped by business models and consumer behavior. A quarter of the world's forest loss is due to the production of basic commodities such as beef, soybeans, palm oil and wood fiber. Mining adds to this problem by contaminating the rivers and streams that are vital for a resilient ecosystem, carbon sequestration and soil quality.
Everyone in the world of global health is worried about what is happening to biodiversity, the climate, and public health.
Ecosystem stress is increasing. The Amazon is near a tipping point due to climate change, which is not at all good for the global ecosystem. If we reach the tipping point, the results will be very bad in terms of drought, fires and of course in terms of disease.
Disease risks must be added to the risk-benefit analysis of new projects that develop. We must take into account the costs of public health when we are considering new plantations or mines. The risks are first for the local populations, but then for the whole world, because we have seen with Covid how quickly diseases can spread.
The solution to these crises lies not only in ending our war on nature, but in our endeavor to restore nature.
To conserve and restore nature, we need to keep the world's forests intact as much as possible. In addition to their role as bastions for biodiversity, they are barriers to deadly pathogens. Karma Virus!