Climate change bares fangs, unleashes heat-related, vector-borne ailments in TN

Another vulnerable population is the one living in areas that previously weren’t as humid as they are now, due to erratic rains and rising humidity. This increases their susceptibility to vector-borne diseases, which is compounded by their lack of natural immunity.

Also read: TN paddy farmers unlearn traditional practices as climate change takes a toll

Dr Ilankumaran Kaliamoorthy, Chief Executive Officer and senior consultant, Liver Anaesthesia and Intensive Care at Rela Hospital, says that the vulnerable population has increased over the years. According to the World Health Organisation (WHO), the vulnerable population has increased by 85 per cent when compared to 2004.

Rise in vector-borne diseases

Among vector-borne diseases, dengue remains the primary concern for the state Health Department, but a surge has also been reported in the number of chikungunya, scrub typhus, and leptospirosis cases in the state over the past few years.

In 2024, Tamil Nadu recorded 26,740 cases of dengue and 13 deaths – the highest in the past six years. While the state recorded 153 cases of chikungunya in 2021, it rose to 181 in 2022, 222 in 2023 and exponentially to 603 in 2024. The number of 181 leptospirosis cases have also seen a gradual spike – from 1,046 in 2021 to 3,526 in 2024. As many as 6,343 cases of scrub typhus, a mite-borne disease, were reported in Tamil Nadu in 2024.

Dr TS Selvavinayagam, the Director of Public Health and Preventive Medicine, agrees that climate change helps create conducive temperature and humidity to facilitate breeding grounds for mosquitoes and other vectors and aid their reproduction.

Watch | Animal farming, not fossil fuels, main trigger of climate change: Expert

“We expect more breeding sites and more mosquitoes. What used to be a seasonal problem may become a perennial problem in future,” he told The Federal.

Scrub typhus, leptospirosis

Meanwhile, scrub typhus, which breaks out amid humid conditions and increased rainfall, has seen a surge after heavy rains in the state over the past few years.

A study titled ‘Climate influences scrub Typhus occurrence in Vellore, Tamil Nadu, India: analysis of a 15-year dataset’, revealed that for 1 per cent increase in mean relative humidity, there was a 7.6 per cent surge in scrub typhus cases and that an increase of 1 mm of rainfall contributed to 0.5-0.7 per cent of monthly scrub typhus cases.

An analytical study to predict leptospirosis cases until 2027 in Tamil Nadu was done by the Directorate of Public Health and Preventive Medicine (DPH) that pointed out an increasing trend of leptospirosis in the state. The study noted a steady increase in cases each year and the prediction were about 3,474 in 2024, 3,677 in 2025, 4,986 in 2026, and 5,785 in 2027.

Rising sea levels, waterborne diseases

Talking about water-borne diseases, Dr Madhumitha, senior consultant, Infectious Diseases and Infection Control, MGM Healthcare, says there has been an increase in waterborne illnesses mainly because of the increase in sea level.

Also read: Power use surge signals heat waves, not necessarily economic growth: Report

“In coastal areas, flooding due to heavy rainfall over short intervals can cause water contamination and infections such as cholera, typhoid, and leptospirosis. Moreover, the increase in temperatures can be favourable for certain bacterial growths like salmonella bacteria that cause typhoid. It grows better in warmer conditions,” she told The Federal.

Heat stress

The extreme summer temperatures in Tamil Nadu have also led to a rise in the number of cases of heat stress and heat-related illnesses. The National Centre for Disease Control states that infants and young children, people working outdoors, pregnant women, people with mental illnesses, and those with heart disease or high blood pressure are highly vulnerable. Heat stroke and dehydration can also lead to kidney-related problems, it says.

“Heat stress is common in elderly people or people who are working outdoors. Sometimes high temperatures can even strain your heart. It can worsen hypertension, and cause strokes, heart attacks,” Dr Madhumitha said.

She added that while anyone can be at risk of heat stress, certain factors may make individuals more vulnerable. Due precautions must be taken by everyone to prevent heat-related illnesses.

Also read: 2024 hottest year on record, first to breach 1.5 degree C guardrail

Doctors also emphasise that research identifying heat stress thresholds for different age groups can help in urban planning, cooling solutions and implementation of early warning systems.

Risk of respiratory infections

Air pollution has also led to a rise in respiratory infections, which could exacerbate health issues such as asthma, chronic obstructive pulmonary disease (COPD), and allergies such as seasonal rhinitis and allergic rhinitis. Additionally, rising levels of pollution make children below the age of 15 susceptible to long-term respiratory conditions, including asthma and chronic lung disease.

A study published in The Lancet's eClinical Medicine Journal indicates that lung cancer tends to manifest approximately a decade earlier in India compared to western countries, with diagnoses commonly made between the ages of 54 and 70, and this is mainly due to rising air pollution.

It said that a significant portion of lung cancer patients in India have never smoked, suggesting that factors like air pollution play a crucial role in the onset of the disease. The earlier onset is partly seen among India's relatively young population, with a median age of 28.2 years, compared to 38 years in the USA and 39 years in China.

Also read: India slams developed countries for climate crisis at ICJ hearing

Early onset of lung cancer

The incidence of lung cancer in India has risen from 6.62 per 100,000 people in 1990 to 7.7 per 100,000 in 2019, with expectations of a further increase, especially in urban areas by 2025. The study, which involved researchers from Tata Memorial Hospital in Mumbai, calls for tailored approaches to lung cancer research and treatment guidelines that are specific to regional contexts in Southeast Asia. Additionally, a study by AIIMS Delhi also stated that India is among the top four most polluted countries in the world and 37 of the world's 40 most polluted countries are in South Asia.

Citing the study, Dr Sujith Kumar Mullapally, consultant of Medical Oncology at Apollo Proton Cancer Centre says that lung cancer is one of the most common types of cancer in India.

How poor soil leads to cancer

He attributes the rise in incidence of lung cancer among youngsters and non-smokers in Tamil Nadu to air pollution. Mullapally also said that more cases of stomach and colon diseases, as well as cancer are being reported because of a decline in soil quality which further affects the food we eat.

Also read: Storms, doldrums and a squadron of giant manta rays: Tale of an ongoing voyage to promote resilience

“There is a surge in the cases of stomach and colon, not just in Tamil Nadu but across the country. Farmers are increasing the use of pesticides to maximise their yield as they are finding climate change as a challenge. The increased use of pesticides in food is also responsible for the increase in cancer cases," he told The Federal.

Toll on mental health

Climate change also takes a toll on the mental wellbeing of individuals.

“A majorly unexplored area of potential research is mental health issues like climate-change anxiety, and depression and Post Traumatic Stress Disorder (PTSD) following major climate-related disasters. Understanding the toll of these changes is essential in formulation of public health policies,’ said Dr Ilankumaran.

Psychologists have noted a surge in mental disorders when extreme temperatures are recorded.

Vandana, a clinical psychologist at V-Cope told The Federal that although climate change is not the only responsible factor for rising incidence of mental health issues, it certainly contributes to the same. “The financial losses due to extreme weather events can lead to anxiety, depression and insomnia. Warmer temperatures can also lead to irritability and mood disorders,” she said.

Also read: Beyond apocalypse: As COP29 goes on, how climate fiction showcases our relationship with Earth

What is the way out?

Emphasising the need for research and policy intervention to bring down the incidence of climate change-related illnesses, Dr Kaliamoorthy, says that early intervention and resource planning can be made possible with AI-based climate models that predict the spread of vector-borne diseases, for starters.

“Climate change is impacting and will continue to impact agriculture, posing a threat to food availability and nutrition. As the summer unfolds and the climate worsens, hospitals and healthcare providers across India must prepare for a climate-induced health crisis. Without appropriate actions, these climate changes will continue to worsen, and soon we will be seeing it as a public health emergency instead of just an environmental issue,” he said.

In order to handle extreme weather events in Tamil Nadu, the Directorate of Public Health and Preventive Medicine issues guidelines to health workers across the state to handle flooding and heatwave. The state Health Department organises health camps and mobile medical camps to identify the cases of water and vector-borne diseases at an early stage to prevent mortality.

‘Coordination, cooperation on multiple levels’

Dr Selvavinayagam, the Director of Public Health and Preventive Medicine said that climate change may affect food security and nutrition as it would impact animal breeding.

Watch: Swelling Himalayan glacial lakes push up flood risk; what’s India’s doing?

“The quality of meat may come down. It may affect the reproduction with less number of births, which would impact the milk production. The quality of vegetables and grass is also likely to come down along with reduced yield from the land, which in turn affects the animals’ production which feed on the plants,” he said

He added that in order to address the challenges due to climate change, we need coordination and cooperation on multiple levels. "We need to minimise the environmental damage and pollution which is happening due to human activities. Additionally, there is a need to minimise the usage of resources as far as possible and reuse it," he said.

The department also holds task force meetings on Climate Change and Human Health to develop Heat Action Plan including the Standard Operating Procedures during heat wave season. The activities for sensitization and capacity building of health staff as well as other line department staff on heat illness and flooding is also being done.