Climate change and infectious diseases

Global climate change has resulted in a wide range of impacts on the spread of infectious diseases. Like other ways in which climate change affects on human health, climate change exacerbates existing inequalities and challenges in managing infectious disease. Infectious diseases whose transmission can be impacted by climate change include dengue fever, malaria, tick-borne diseases, leishmaniasis and Ebola virus disease. For example, climate change is altering the geographic range and seasonality of the mosquito that can carry dengue. One Health, a model that considers veterinary and human health parts of an integrated whole, is partly a response to the increase of epidemic risks that arise from climate change. There is no direct evidence that the spread of COVID-19 is worsened or is caused by climate change, although investigations continue. In 1988, little was known about health issues caused by global climate change. The Intergovernmental Panel on Climate Change has so far published six assessment reports, the latest being the Sixth Assessment Report which summarises the scientific understanding about climate change, potential health risks caused by climate change and early evidence of actual health impacts. Climate change affects vector-borne diseases by affecting the survival, distribution and behavior of vectors such as mosquitoes, ticks and rodents. The viruses, bacteria and protozoa are carried by these vectors transferring them from one carrier to another. Vector and pathogen can adapt to the climate fluctuations by shifting and expanding their geographic ranges, which can alter the rate of new cases of disease depending on vector-host interaction, host immunity and pathogen evolution. This means that climate change affects infectious diseases by changing the length of the transmission season and their geographical range. Worryingly, vector-borne diseases have in the past led to the rise and fall of civilizations. This is why the World Health Organization considers climate change as one of the greatest threats to human health.