Of late, several studies have suggested that rising temperatures may exacerbate snakebite cases, sounding an alarm bell for India, which already has a high incidence of envenomation. However, several experts disagree, while others opine that while climate change does impact snakes like all other species, whether or not snakebites rise is an altogether different matter, depending on several other factors apart from temperature. TreeTake takes a look …
India has a high number of snakebite cases, which now need a serious look as a health hazard, because studies suggest that a significant increase in snakebites is expected due to climate change, as it creates more favourable habitats for venomous snakes in new areas, particularly in India and other tropical and subtropical regions. Researchers link a 1°C increase in daily temperature to a 6% rise in snakebites, with the risk increasing in previously less-affected northern and northeastern states and districts. This trend necessitates enhanced public health measures, including awareness campaigns and improved healthcare readiness, to mitigate the public health crisis posed by rising snakebite incidents and fatalities.
How climate change might push up snakebite risk
Habitat expansion: Rising temperatures and humidity are expanding the habitats for venomous snakes, such as the Indian Big Four (Cobra, Russel’s Viper, Indian Saw-scaled Viper and Common Krait) into areas not previously considered high-risk. Climate change is reshaping the habitats of venomous snakes, increasing human exposure, and leading to snakebites in previously unaffected areas.
Increased human-snake encounters: The expansion of snake habitats into populated areas would lead to more encounters between humans and venomous snakes, thereby increasing the likelihood of bites.
Direct temperature link: Research indicates a direct correlation between rising daily temperatures and an increase in snakebite incidents, with spring temperatures showing the strongest association.
The researchers also say northern and northeastern states, such as Haryana, Rajasthan, Assam, Manipur, Meghalaya, Nagaland and Arunachal Pradesh are poised for a significant rise in snakebite risk. Snakebites may also rise in many North and South American countries by 2050, with risk areas shifting northward in Canada and southward in Argentina and Chile.
What would be the impact on public health?
The World Health Organisation (WHO) recognises snakebite as a neglected tropical disease that, like dengue and malaria, is spreading geographically due to climate change. Therefore, the projected increase in snakebites is seen as a looming public health crisis, especially in regions with vulnerable populations and limited healthcare capacity. The World Health Organisation (WHO) estimates that about 5 million snakebites occur in India each year, resulting in up to 2.7 million envenomings. Published reports suggest that between 81,000 and 138,000 deaths occur each year. Snakebite envenoming causes as many as 400,000 amputations and other permanent disabilities. Many snakebites go unreported, often because victims seek treatment from non-medical sources or do not have access to health care. As a result, it is believed that many cases of snakebite go unreported.
What experts say
Professional herpetologist and Wildlife SOS Agra Bear Rescue Facility’s Senior Wildlife Biologist and Director of Conservation Projects, Baiju Raj concurred with the view of climate change impact on snakes. However, he demurred on the fact whether or not it would push up snakebite cases. “Climate change has an impact on every animal or reptile, not only snakes. Snakes are ectotherms; their entire body works with the external temperature, that is ambient temperature. So they will be the most affected species when climate changes happen. That is because when it is warm, they want a little warmer place or a normal place. When it is extremely cold, they come out to get a warm place. When it is extremely hot, they go to a moderately warm place, like a muddy area, to regulate their body temperature. So, climate change does impact them. Take the instance of Kerala, we can see or encounter snakes all 365 days of the year because of the very good weather. They come out every day. But in northern India, we get snakes mostly in the monsoon season. In the cold winter, we don't get snakes much, but some are rescued as they come out to bask in the sun and people encounter them.”
“However, about snake bite cases, we cannot exactly tell if they will rise because it depends on people. Snakes bite only when they are hurt. They never bite when not meddled with. A snake will not just come and bite anybody. But if you step on it, even by mistake, it is sure to do so. So that depends on people, irrespective of the weather. The problem is when one encounters a snake, one tries to fiddle with it and gets bitten,”he added.
“However, awareness among people and adequate anti-venom (antidote) supply are of the utmost importance. In Lucknow, we are working with the Relief Commissioner’s Office. I’m coordinating with them and they are planning to jot down all the snake rescuers in a database. The commissioner has written a letter to the Chief Wildlife Warden to trace all the snake rescuers in every area to mitigate snakebites. Many rescuers are illegal. They just rescue for fun or for Facebook and WhatsApp pictures. They do not want to be added to the database because they are doing it for a time pass and only for the video and money. Their real work is not awareness, conservation or education. This is the problem,” he pointed out.
HV Girisha, Chief Conservator of Forests (Jhansi), Department of Forests and Wildlife, Uttar Pradesh did not agree to the view that rising temperatures might push up snakebites. “I do not know how there is a simple correlation between the increasing number of snake bites with the increasing temperature. That is a different issue. But the real issue is that we have around 52,000 plus deaths every year in India, and among them, we have around 15 to 17,000 from UP alone. So, it is not just because of increasing temperature, it is because of the quality of venom extracted for the antidote as well. There is an apex-level expert committee constituted by the NCDC. I am one of the members in that. There are a lot of discussions going on over this. One of the reasons that is highlighted is that we have polyvalent antidotes for snakebites now. Polyvalent means we have only four identified venomous snakes and we mix the venom of all these to make an antidote. In one recent case, the doctor had to inject 76 doses just to keep the victim alive. That shows there is an inefficacy of anti-snake venom. Saying that as the temperatures rise, the snakes migrate to regions where they were not seen before is again wrong because snakes are also territorial. There are scientists who are working on catching snakes for venom collection and releasing them elsewhere or snakes are rescued from urban areas and released in forests. These snakes die. There are studies for this. People have experimented microchipping the cobras collected from somewhere and then releasing them somewhere else, only to find them dead. They did not survive in those forest areas. They are also territorial. I do not buy this theory of migration from one region to another in response to rising temperatures. Snakebites increase because we are losing a lot of grassland. All of that land is being used for cultivation, with the use of a lot of pesticides in the agricultural fields. The snakes used to thrive on insects as well as frogs and other small animals in all the cultivated areas. Now we are simply losing all those micro animals that were actually playing an important role in the food chain. Snakes were dependent on them. That is why most snakebites occur in rural areas.” He also said that snakes thrived in arid and dry climates, like in deserts, and cited the example of the sand viper, negating the theory that climate change might propel snakes towards cooler climes.
Abhishek Dubey, wildlife activist and founder of Nature Club Gonda, said climate change and rising global temperatures were directly affecting the behaviour of snakes and their interactions with humans. Since snakes were cold-blooded creatures, more heat intensified their body’s actions and they became more active and aggressive. During the hot and rainy season, snakes were more visible around farms, houses or settlements, increasing the chances of encounter with humans. At the same time, changing temperature and rainfall patterns were expanding the geographic range of snakes, meaning they were reaching places where they were rarely or not found at all before, he said.
“This is having a direct impact on rural and agriculture-based communities, where people spend more time on farms or outdoors and the risk of being bitten increases. During floods or disasters, snakes leave their natural habitats and invade human settlements, further increasing the risk. Research shows that snakebite cases increase rapidly during times of high temperature and high rainfall in regions such as India, Africa and Latin America. Therefore, snakebite incidents may become even more frequent, widespread and management-challenging in the future due to rising global temperatures and unstable climates,” he said.
What studies say
In Haryana, Rajasthan and Assam, the habitat suitable for the ‘Big Four’ snakes may be expanded due to climate change, rising heat and humidity, said researchers from Dibru-Saikhowa Conservation Society and Assam Agricultural University, and Pukyong National University in South Korea. They also foresaw more human-snake encounters in rural as well as urban areas, which could pose a significant health challenge for the people. They also felt that states like Manipur, Meghalaya, Nagaland, and Arunachal Pradesh, which do not have a conducive habitat at present, may also be susceptible if temperatures continue to rise.
Emory University researchers also say there is a greater likelihood of being bitten by a snake for every degree Celsius rise in daily temperatures. Their study was based on emergency department visits reported by the Georgia Hospital Association from 2014 to 2020. In this period, there were more than 5,000 hospitalisations due to snakebites. The researchers compared this with the minimum and maximum temperatures, air pressure and humidity on the dates the bites occurred. The researchers then compared that data with the temperature on other days within the same month and on the same day of the week, which also helped account for variability in human activity.
The findings, published in GeoHealth, concluded that the risk of being bitten by a snake increased 6% for every degree Celsius rise in daily temperatures. According to the lead author of the study, Noah Scovronick, climate change is a matter of concern as the temperature effects may impact populations which lack access to health care. He said more efforts should be made to understand and counter the health threat from snakebites in the context of climate change.
As per the US National Library of Medicine website: “Current evidence indicates that climate change will lead to a change in snakebite burden and there is a need for primary healthcare systems to be prepared for this. However, more transdisciplinary research is required to comprehensively understand the issue, going beyond incidence, especially in countries with a high burden of snakebite. Community-based approaches for biodiversity and prevention, together with improving resilience of primary care and public health systems, are required to mitigate the impact of climate change on snakebite.”
The PLOS Neglected Tropical Diseases website said: “Climate change is anticipated to significantly impact the biogeographic distribution of snakes, leading to notable shifts in their habitats toward anthropogenic landscapes. This may potentially increase the incidence of Big Four species (Bungarus caeruleus, Daboia russelii, Echis carinatus, and Naja naja) envenomation, a notable human-health risk that has not yet been assessed in India being the most affected country in South Asia.” The Snakebite Risk Index, developed by the researchers that integrates climate data, geographic spread of snakes, and socioeconomic vulnerability, identifies Karnataka (Chikkaballapura, Haveri, Chitradurga) and Gujarat (Devbhumi Dwarka, Jamnagar), Assam (Nagaon, Morigaon, Golaghat), Manipur (Tengnoupal), and Rajasthan (Pratapgarh).
All studies underline the urgent need for targeted public health strategies in both affected regions and emerging hotspots.
As per the studies, several northeastern states, such as Manipur, Meghalaya, Nagaland, and Arunachal Pradesh, which were hitherto considered low-risk for snakebites, may see a rise of over 100% in suitable snake habitats under future climate scenarios, so that a large number of people would be exposed to snakebite risks and challenges, although they have limited access to healthcare. The rise in human-snake interactions, both in rural farming areas and rapidly urbanizing zones and subsequent increase in snakebite cases could burden the healthcare systems, particularly rural health facilities. Thus, there is an urgent need for public education, emergency response training, reliable surveillance systems and accessible anti-venom supplies.
Indian scenario
In India, snakebite is a significant medical challenge, given that it has one of the highest numbers of snakebite cases and fatalities worldwide. As studies say rising temperatures and humidity could shift snake habitats toward northern and northeastern states, increasing human-snake encounters in rural and urban areas alike, the potential spread of the ‘Big Four’ venomous snakes—Cobra, Krait, Russell’s Viper, and saw-scaled viper—poses serious risks and highlights the urgent need for improved awareness, prevention strategies and healthcare readiness across the country.
What is needed
Public awareness: Public awareness campaigns about the risks and preventive measures should be intensified.
Healthcare readiness: Healthcare systems should be strengthened and readiness improved to respond to increased snakebite cases. |
“Everybody has to be alert. Every PHC should have anti-venom medicines. The problem is that many people do not go to hospitals even now and rely on indigenous medicine or ‘jhar phoonk’. Recently, a 10-year-old girl died near our facility in Agra because by the time her kin took her to the hospital, it was too late. Even hospitals do not have the required anti-venom all the time. Besides, anti-venom injections are costly, so poor people avoid such treatment. In Kerala, where we find snakes throughout the year, every PHC and all health centre has anti-venom injections. These should be made available in all PHCs and there should be a doctor’s unit to take care of this. We are going to work with Rajasthan government to set up a small helpline clinic in Rajasthan to mitigate snakebites in Rajasthan near Ranthambhor area. Many people cannot reach hospitals. So, we are trying to set up a mobile clinic which can go to the people. Also, hospital doctors should be aware of what to do. There should be a trained staff, trained doctors. Now in India, you don’t need to identify a snake. They don’t need to know which snake has bitten because all four snakes’ venom, like Cobra, Krait, Russell’s Wiper and Sawscale, is mixed for the antidote. For every snakebite, the same antivenom is going to work. All doctors, junior or senior, should be aware of this. Antidotes should be available in sufficient quantity and awareness programmes should also be run, particularly in all the schools. In Tamil Nadu, every village kid knows what to do in case of a snakebite,” said Baiju Raj.
Integrated approaches: Climate modelling, species distribution and socioeconomic vulnerability data should be combined to develop effective prevention and control strategies. Access to anti-venom in high-risk regions must be improved. Rural healthcare systems must be strengthened to handle envenomation cases. Communities need to be educated on snakebite prevention and first-aid measures. Climate change should be suitably countered and mitigated to reduce habitat expansion for venomous snakes. Proactive public health strategies need to be combined with with climate action to protect vulnerable populations and reduce future snakebite mortality. It is vital to strengthen surveillance systems, ensure timely antivenom availability and improve awareness to reduce fatalities and disability caused by snakebites.
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