In its latest report released this March, the Intergovernmental Panel on Climate Change (IPCC) delivers a stark warning: climate change heightens the global risk of infectious diseases. The close relationship between climate and disease is being demonstrated every year. For instance, the periodicity of mosquito-borne disease outbreaks no longer follows expected patterns. Dengue manifests in two to three peaks throughout the year. Variability in temperature, precipitation, and humidity disrupt disease transmission cycles. These also alter the distribution of the vectors and animal reservoirs that host the parasite. Heat has been proven to interfere with the genomic structure of pathogens, changing their infectivity and virulence.
Climate change, more infections
Habitat loss forces disease-carrying animals to encroach upon human territory, increasing the risk of human-animal interaction and the transfer of pathogens from wildlife to humans. Viruses which do not harm animals can be fatal for humans. Nipah virus, which has been causing outbreaks in Kerala for many years now, is a good example. An analysis of 2022 published in Nature Climate Change warns that humans now face a broader spectrum of infectious agents than ever before. Over half of all-known infectious diseases threatening humans worsen with changing climate patterns. Diseases often find new transmission routes, including environmental sources, medical tourism, and contaminated food and water from once-reliable sources. While ecosystems shape local climates, climate change is transforming ecosystems. This dynamic introduces invasive species and extends the range of existing life forms. Both these trigger upheavals in ecosystems that are complex and confound ecologists and epidemiologists to predict outbreaks. Human-induced climate change is unleashing an unprecedented health vulnerability crisis. India, in particular, has felt the ominous impact, with early summers and erratic monsoons causing water scarcity across the Gangetic plains and Kerala. These climatic shifts are manifesting in severe health crises, including a dengue epidemic in Dhaka (Bangladesh) and Kolkata and the Nipah outbreak in Kerala. Why should we not be surprised at the recent outbreaks in Kolkata or Kerala or at its un-seasonality?
