Zika, dengue, malaria: half of infectious diseases will be more severe in the future

While it is relatively well accepted that the climate change increases the risk of transmission of pathogenic diseases to humans, in particular because of the continuous emission of greenhouse gasthe quantification of this risk remained unclear. On the one hand, the emission of greenhouse gases increases climate risks to the Earth system – for example, global warming, waves of heat, forest firesthem precipitation extremes or sea level rise. On the other hand, there is a great diversity of pathogenic diseases (bacteria, virusanimals, plants, mushrooms, protozoaetc.) and types of transmission (vector, airborne, direct contact, etc.)

The researchers of the study published in the journal Nature Climate Change performed a systemic search of more than 70,000 scientific articles. This is to find examples of the impacts of 10 climatic hazards – sensitive to emissions greenhouse gases – on already known human infectious diseases. Result: 58% (i.e. 218 out of 375) of the infectious diseases with which humanity is confronted in the world have at some point been aggravated by at least one climatic hazard (for example Zika, the denguepneumonia or malaria).

Over 1,000 unique transmission paths

In total, there are no less than 1,006 unique transmission routes in which climatic hazards have led to pathogenic diseases. ” There are simply too many diseases, and transmission routes, for us to think we can truly adapt to climate change. “, said in a press release Camilo Mora, professor of geography at College of Social Sciences and lead author of the study. ” This highlights the urgent need to reduce greenhouse gas emissions globally. »

The research team has made available to the public an interactive webpage which shows each link between a climatic hazard and a case of disease. The tool thus allows users to query specific hazards, pathways and disease groups, and visualize the available evidence.

Pathogens and humans displaced by climate hazards

The researchers explain these results by the fact that climatic hazards bring pathogens closer to humans. Indeed, the climatic changes promote the expansion ofrange vectors and pathogens, with, in addition, better conditions for reproduction and life cycles. For example, warming and changes in precipitation are associated with the expansion of the range of mosquitoesticks, fleas, birds and many mammals implicated in virus outbreaks.

Furthermore, the storms, flooding and sea level rise have resulted in human displacement and thus more cases of gastroenteritis, salmonellosis, respiratory diseases and skin diseases – among others. These populations are sometimes forced to live in the stress and with insufficient conditions to combat these infections.

It should be noted that 16% of illnesses (i.e. 63 out of 286) were reduced by climatic hazards. However, most of these illnesses have sometimes been aggravated by another hazard…or by the same hazard.