Tackling New Disease Scenarios in the Face of Climate Change
Climate Change and Infectious Diseases: A Growing Threat
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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.
The Impact of Climate Change on Disease
Climate change has far-reaching implications for the spread of infectious diseases. Here are some key points to consider:
- Changing Disease Patterns: 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.
- New Transmission Routes: An analysis 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.
- Ecosystem Disruption: While ecosystems shape local climates, climate change is transforming ecosystems. This dynamic introduces invasive species and extends the range of existing life forms. Both of these trigger upheavals in ecosystems that are complex and confound ecologists and epidemiologists to predict outbreaks.
India’s Vulnerability to Climate-Induced Diseases
Human-induced climate change is unleashing an unprecedented health vulnerability crisis in India. Early summers and erratic monsoons are 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.
Surveillance and Reporting Challenges
Changed disease scenarios require a revision of strategies to detect and deal with them. India has improved its reporting of outbreaks over the past two decades. However, the current design of surveillance is not adequate for the emerging disease scenario. Mitigating the spread of climate change-induced diseases requires safeguarding ecosystems, curbing greenhouse gas emissions, and implementing active pathogen surveillance.
The One Health Approach
A unified approach, termed One Health, which integrates monitoring human, animal, plant, and environmental health, recognizes the interconnectedness of these aspects. This approach is pivotal in preventing outbreaks, especially those that originate from animals. It encompasses zoonotic diseases, neglected tropical diseases, vector-borne diseases, antimicrobial resistance, and environmental contamination.
India must launch One Health and infectious disease control programs by building greater synergies between the Centre and States and their varied specialized agencies. Animal husbandry, forest and wildlife, municipal corporations, and public health departments need to converge and set up robust surveillance systems.
The Ongoing Challenge of Known Diseases
Globally, there is an obsession with the enigmatic “disease X,” but it is the familiar annual cycles of known agents such as influenza, measles, Japanese encephalitis, dengue, and diarrhoea among others that will continue to test the public health system. Climate change is not limited to infectious diseases. It also exacerbates injuries and deaths from extreme weather events, respiratory and cardiovascular diseases, and mental health issues.
Embracing the One Health Paradigm
In the face of a changing climate and the growing threat of infectious diseases, protecting ecosystems, fostering collaboration, and embracing the One Health paradigm are our best defenses. The road ahead demands concerted efforts, not just to adapt but also to proactively safeguard our planet and its inhabitants.