A recent paper published in the journal Nature Climate Change showed that climate change could exacerbate about 50% of recognized human pathogenic diseases.
Study: More than half of known human pathogens may be exacerbated by climate change. Image credit: Photography by Sepp
background
The continuous release of greenhouse gases (GHGs) is increasing several climate risks, which in turn worsen human disease pathogens. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, which amply demonstrated the social disruption caused by infectious diseases, offers alarming clues about the possible outcomes of impending health crises caused by climate change.
Although it is well established that climate change influences disease pathogens, the degree of human susceptibility to disease pathogens affected by climate change is not fully known. With few outliers, previous research on the relationship between climate hazards and human pathogenic diseases has typically focused on certain classes of pathogens (such as bacteria or viruses), climate hazards (such as warming, precipitation, or floods) or modes of transmission (such as vector, food, water). Therefore, measuring the full threat to humans caused by climate change as it connects to pathogenic diseases is hindered by the inability to combine the available information.
About the study
In the present study, the researchers methodically searched for empirical evidence of the effects of 10 GHG emission-sensitive climate changes on each recognized human pathogenic disease. The 10 GHG-sensitive climate hazards analyzed in the research were drought, warming, wildfires, heat waves, floods, precipitation, sea level rise, storms, climate change land cover and ocean climate change.
The team conducted three interdependent literature searches to identify case reports of pathogenic diseases affected by climate hazards. In the first search, they conducted separate investigations for each combination of the term “disease” with each of the 10 climate hazards identified as sensitive to GHG emissions. In the second search, the researchers conducted separate searches of scientific articles that combined the name of each disease from two reliable infectious disease databases with each of the 10 climate hazards.
The authors then performed additional queries for disease and climate risk combinations in which the previous two searches did not provide any cases. They first generated a table showing all diseases identified by searches 1 and 2 as rows and each climate risk as columns. Additionally, the team used alternative names for pathogens and diseases in the third search. Additionally, they used Google Scholar for all queries.
results
The authors found 3,213 empirical cases in which climate hazards were linked to disease pathogens. These case examples were related to 286 different disease pathogens, 277 of which had at least one worsening climate risk. While some climate hazards decreased 63 diseases, 54 of them were occasionally aggravated by other climate hazards. In fact, climate hazards only uniquely reduced nine pathogenic diseases.
Scientists documented diseases that worsen climate hazards. The collection of pathogenic diseases exacerbated by climate hazards represents 58% of all identified infectious diseases affecting humanity globally. In detail, climate hazards aggravate 218 of a reliable list of 375 pathogenic diseases that have been observed to have influenced human beings.
The team identified 1,006 different routes by which climate hazards, through various modes of transmission, led to the emergence of pathogenic diseases. They noted that 76, 69, 45, 24, 23, 12, and nine diseases caused by viruses, bacteria, animals, fungi, protozoa, plants, and chromists, respectively, were influenced by warming, precipitation, flooding, drought , the storms, the earth. land cover change, ocean climate change, fires, heat waves, and sea level rise associated with 160, 122, 121, 81, 71, 61, 43, 21, 20, and 10 unique diseases, respectively.
Vectors mainly spread pathogenic diseases, i.e. 103 different diseases. However, the researchers also found 78, 60, 56, and 50 unique examples of disease cases for the transmission channels transmitted by water, air, direct contact, and food, respectively. There were 19 common disease names (such as gastrointestinal infections) without data on the causative pathogen among all examples of pathogenic disease cases adversely affected by climate hazards. In addition, there were no details on the transmission mechanism of 116 diseases.
Conclusions
Overall, in the current research, the team found that climate hazards exacerbate 58% (that is, 218 out of 375) of the infectious diseases experienced by humans globally at some point. On the other hand, occasionally pathogenic diseases decreased by 16%. Empirical cases demonstrated 1,006 different ways that climate hazards led to pathogenic diseases through various methods of transmission.
In particular, climate risks exacerbate too many human pathogens and modes of transmission, exceeding the adaptive capacity of society, underscoring the urgent need to address the root cause of the problem, which is to reduce GHG emissions.