Effects of Climate Change Making Over 200 Human Pathogenic Diseases More Severe, Says Study
As the globe struggles with COVID-19 and monkeypox, a study reveals that more than 200 human pathogens have been exacerbated by climate change and are likely to worsen in years to come.
According to a study published in the journal Nature Climate Change, more than 58 per cent, or 218 out of 375, of known human pathogenic diseases, such as dengue, hepatitis, pneumonia, malaria, and Zika, have been affected by at least one climatic hazard via 1,006 unique pathways.
The increasing capacity of pathogens to cause more severe illnesses has also been linked to climatic hazards.
Camilo Mora, a geography professor in the College of Social Sciences (CSS) at the University of Hawaii at Manoa, said:
"Given the pervasive consequences of the pandemic, it was truly scary to discover the massive health vulnerability resulting as a consequence of greenhouse gas emissions. There are just too many diseases and pathways of transmission for us to think we can truly adapt to climate change. It highlights the urgent need to reduce greenhouse gas emissions globally."
The researchers conducted a systematic search for empirical evidence about the effects of 10 climate hazards sensitive to greenhouse gas (GHG) emissions on each known human pathogen.
These risks include warming, drought, heatwaves, wildfires, extreme precipitation, floods, storms, sea level rise, ocean biogeochemical change, and land cover change.
The researchers then combed through over 70,000 scientific papers in search of evidence of each potential combination of a climate hazard affecting each of the known diseases.
According to the research, warming, precipitation, floods, drought, storms, land cover changes, ocean climate change, fires, heatwaves, and sea level changes are known to influence diseases caused by viruses, bacteria, animals, fungus, protozoa, plants, and chromists. Pathogenic diseases were transmitted mostly through vectors.
Natural disasters are pushing diseases closer to humans. The data revealed that numerous climate hazards are expanding the range and duration of environmental suitability, thus aiding the geographical and temporal proliferation of vectors and diseases.
Warming and precipitation changes, for example, were associated with the range expansion of vectors such as mosquitoes, ticks, fleas, birds, and several mammals implicated in outbreaks of viruses, bacteria, animals, and protozoa, such as dengue, chikungunya, plague, Lyme disease, West Nile virus, Zika, trypanosomiasis, echinococcosis, and malaria.
Multiple aquatic diseases, including Vibrio (a kind of bacteria)-associated infections, primary amoebic meningoencephalitis, and gastroenteritis, have been linked to heatwaves.
The study revealed that storms, floods, and sea level rise were responsible for human displacements that contributed to cases of leptospirosis, cryptosporidiosis, Lassa fever, giardiasis, gastroenteritis, Legionnaires' diseases, cholera, salmonellosis, shigellosis, pneumonia, typhoid, hepatitis, respiratory diseases, and skin diseases, among others.
In addition to reducing the capacity of humans to resist diseases, climatic dangers have altered body conditions, such as increasing stress through exposure to dangerous situations, thereby weakening the human immune system.
"We know that climate change can affect human pathogenic diseases," said study co-author Kira Webster.
While the vast majority of diseases were shown to be exacerbated by climatic hazards, some were found to be mitigated (63 out of 286 diseases).
For instance, warming appears to have slowed the spread of viral illnesses, maybe due to improper settings for the virus or a stronger immune system in warmer environments.