Climate hazards such as global warming, flooding, heat waves and drought have at times aggravated 58 per cent of infectious diseases affecting humans, according to a review of scientific studies published in the journal Nature Climate Change. The study underlines the implications that climate change has for public health. Out of a list of 375 infectious diseases that affect humans, the authors found evidence in scientific literature of cases where 218 had been aggravated by climate hazards. The same study revealed 1,006 unique pathways in which climatic hazards, via different transmission types, led to pathogenic diseases.
"Climate change is a human health issue, not just an environmental issue," Erik Franklin, associate research professor at the Hawaii Institute of Marine Biology at the University of Hawai'i at Manoa, told Health. "Based on prior research, we expected to find some relationships between climate hazards and diseases but the sheer number of pathways (over 1000) was a wake-up call that climate change will have a dramatic impact on human health," Franklin said.
The University of Hawai'i study highlighted that diseases–including anthrax, cholera, malaria, Lyme disease, West Nile virus and the Zika virus–had been documented to have spread more easily in certain cases as a result of 10 climate hazards, including warming temperatures, droughts, heat waves, wildfires, intensifying precipitation and storms, floods, sea-level rise, ocean acidification and changes in natural land cover, such as human-induced deforestation.
Based on the study, researchers uncovered four basic relationships between climate and human disease:
1. Climate hazards, such as global warming, floods, and droughts, affected insects and animals carrying diseases by bringing them in closer contact with humans.
2. Humans, in turn, reacted to climate hazards by moving closer to the sources of the diseases.
3. Some diseases were also strengthened by climate hazards.
4. In some cases, humans' immune systems were weakened by climate hazards, which made them more susceptible to diseases.