Venomous snakes that cause the most deaths in India are expected to shift their habitats northward and into the country’s northeast as climate change alters temperature and rainfall patterns, according to a new research. The study warns that this movement could expose millions more people to the risk of snakebites in areas that have so far seen fewer cases.
The findings were published in the journal PLOS Neglected Tropical Diseases by a team of scientists from India and South Korea. The paper is titled Future of snakebite risk in India: Consequence of climate change and the shifting habitats of the big four species in next five decades.
The “Big Four”
Four snake species are responsible for most serious snakebite cases in India: the Indian cobra (Naja naja), common krait (Bungarus caeruleus), Russell’s viper (Daboia russelii), and saw-scaled viper (Echis carinatus). Together, they are known as the “Big Four.”
These species account for more than 90 percent of venomous bites in the country. India records an estimated 46,000 to 60,000 snakebite deaths every year, the highest number in the world.
“Globally, snakebites kill an estimated 81,000 to 138,000 people each year, with India contributing a large share of these deaths.
“The vulnerability assessments by previous studies indicate exposure to these snakes, which lack effective antivenom treatments,” the researchers wrote. “The Big Four species are thus considered the most medically significant and dangerous snake species in the region.”
While other venomous snakes exist in India, their bites are less frequent and cause fewer deaths.
The study used climate models and species distribution data to map where the Big Four snakes currently live and how their ranges may change in the coming decades. The team relied on data from the International Union for Conservation of Nature (IUCN) and conducted geographic information system (GIS) analyses.
Their goal was to build a district-by-district “risk index” that combines climate projections, socioeconomic conditions, and healthcare access. This allowed them to estimate not just where snakes might move, but also how prepared those regions are to handle potential snakebite cases.
According to the analysis, climate change is likely to shrink suitable habitats for these snakes in some of their current strongholds while opening up new regions further north and east.
“In future climatic scenarios, the Big Four snake species are projected to experience a decline and shift in their geographic ranges, primarily towards Northern and Northeastern India,” the study said.
Southern Decline, Northern Expansion
The saw-scaled viper currently has an extensive suitable habitat in Karnataka. That state may see a reduction of 12 to 44 percent in suitable areas, particularly outside its western region. Gujarat is also listed as highly vulnerable today, especially in districts such as Devbhumi Dwarka and Jamnagar.
But climate projections show that states like Haryana, Rajasthan, and Assam could see an expansion of snake habitats. For example, Rajasthan’s Pratapgarh district and Assam’s Nagaon, Morigaon, and Golaghat districts are expected to face growing risks.
Even more striking is the forecast for states that currently have little or no presence of these snakes. Manipur, Meghalaya, Nagaland, and Arunachal Pradesh are all projected to gain suitable habitats. The study notes that these states could see increases of more than 100 percent in snake habitat suitability by mid-century.
“States such as Manipur, Meghalaya, Nagaland, and Arunachal Pradesh, which currently lack any suitable habitat, are predicted to experience notable increases in habitat suitability for the Big Four in future climate scenarios,” the authors wrote.
Snakebite is classified as a Neglected Tropical Disease by the World Health Organization (WHO). The problem is concentrated in rural farming communities where people often work barefoot in fields or sleep in poorly protected homes.
In Bihar, 35-year-old daily wage laborer Rajesh Manjhi died in 2022 after a snake bit him while he slept at home. His wife, Kiran Devi, recalled that their house lacked electricity and the snake must have slithered in at night. She now struggles to raise their children alone.
Dr. Shantanu Kundu, one of the study’s authors, said the shift in snake habitats poses a major challenge for healthcare systems. “As the Big Four expand into new areas, people who are not used to living with these snakes will face greater risks. Local health facilities may not be prepared to treat the increase in snakebite cases,” he explained.
The research highlights the overlap between future snake habitats and agricultural or urban areas. This means more encounters between snakes and people are likely.
“Such changes may increase human-snake interactions across rural and urban areas, presenting new challenges for public health and medical management,” the paper said.
Building Risk Index & Climate Change
To identify the regions most at risk, the researchers combined several factors: projected snake habitats, cropland and built-up areas, socioeconomic conditions, and the number of healthcare facilities.
Rising temperatures and humidity could push these snakes northward and into the country’s northeast, increasing human-snake encounters in both rural farms and expanding towns.
They found that parts of southern India remain highly vulnerable today, especially in Karnataka districts such as Chikkaballapura, Haveri, and Chitradurga. But northern and northeastern districts are expected to join the high-risk list in the future.
“The risk index identified several southern Indian states and districts as having high vulnerability to snakebite,” the authors wrote. “Additionally, under climate change scenarios, many northern and northeastern states and districts have experienced an increased risk of snakebite, presenting a significant public health concern.”
Experts say the study is significant because it links climate change directly to health risks that are often overlooked. Snakebite already kills more people in India than any other country. If the Big Four snakes expand into new territories, the death toll could rise further unless steps are taken now.
“This is the first study in India to integrate climate-based species distribution models with socioeconomic vulnerability and healthcare capacity,” said lead author Imon Abedin. “It shows that climate change is not just an environmental crisis but also a looming public health crisis.”
The crisis is not limited to India. Across Southasia, snakebites remain a major but underreported threat. Pakistan is estimated to record between 30,000 and 50,000 snakebites a year, Bangladesh more than 400,000, Sri Lanka up to 60,000, and Nepal tens of thousands annually. Experts link climate change to rising cases across the region, from floods in Kerala and Pakistan to heatwaves in Nepal and Bangladesh.
The WHO has set a goal of cutting snakebite deaths and disabilities by 50 percent by 2030. Achieving this target will require better data collection, stronger healthcare systems, and more effective antivenoms.
Local Impact
For people living in rural Assam, the threat is already real. Farmers there report frequent encounters with cobras and kraits, especially during the monsoon season.
“I have lost two neighbors to snakebites in the last five years,” said Ranjit Das, a farmer in Nagaon district. “We know the risk during planting season, but hospitals are far and sometimes there is no antivenom available.”
Health workers in the region are concerned about the predicted rise in cases. Dr. Hemanta Saikia of Assam Agricultural University, another author of the study, said, “We need to prepare local hospitals now, not after the problem worsens. Training, stockpiling antivenom, and educating communities are essential steps.”
The study also acknowledged limitations. Snake occurrence data are difficult to collect in rural areas, which means actual distributions may be underreported. Land use changes such as urbanization and deforestation could also affect snake habitats in ways not captured by climate models.
Still, the authors argue that the overall trend is clear. Rising temperatures and shifting rainfall will reshape where the Big Four snakes live, and people in northern and northeastern India must be prepared.
What Comes Next
The researchers call for coordinated action involving governments, local health agencies, and international organizations. Investments in antivenom production, rural healthcare infrastructure, and community awareness programs are critical.
“Addressing the challenges posed by these species as a result of climate change will require coordinated interventions from government authorities, regional and state health organizations, and the international community to manage this neglected tropical disease effectively in India,” the paper concluded.
For villagers like Das in Assam, preparation cannot come soon enough. “We cannot stop snakes from coming,” he said. “But we should at least have the medicine and doctors to save lives.”
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