Bite of the Big Four: India’s deadly snakebite crisis

Bite of the Big Four: India’s deadly snakebite crisis

Every year, an estimated 5.4 million people worldwide are bitten by snakes, resulting in as many as 138,000 deaths and three times as many cases of permanent disability.

The World Health Organization classified snakebite as a neglected tropical disease in 2017 and set a target to halve related deaths by 2030.

India, home to over 300 snake species, is at the heart of this global health issue, accounting for half of all snakebite-related deaths.

While 95% of Indian snakes are non-venomous, it’s “The Big Four” species — the Indian cobra, common krait, Russell’s viper and saw-scaled viper — that cause the most harm said Dr. Sushil John, a public health doctor and amateur herpetologist from Vellore.

“These snakes cohabit in the same spaces as humans, thriving in India’s agricultural fields, forests and urban outskirts,” said John. “So, they often come into close contact with people and might bite them.”

A study conducted between 1998 and 2014, called the Million Death Study, found that almost 58,000 people in India died from snakebite each year. Second to India in recorded snakebite deaths is Nigeria, with a reported 1,460 deaths per year. 

The missing data

“Though India had a severe snakebite problem, accurate data on snakebite deaths in India was elusive for a long time,” said Dr. Ravikar Ralph, a physician at the Poison Control Centre at CMC Vellore.

In 2011, the official reported number of snakebite deaths was only 11,000. The deaths reported in the Million Death Study highlighted the severe underreporting of snakebite mortality in the country.

“This is because most studies available at the time were hospital-based, which led to the gross under-reporting of this issue,” said Ralph. “We knew from grassroots work that most patients were not reaching hospitals on time.”

“Either people didn’t realize that being bitten by a snake required medical management, or they went to traditional healers, causing fatal delays in hospital-based care,” said Ralph. “The Million Death Study used community-based data collection to circumvent that barrier and document accurate numbers.”

Harvesting the cure

Snakebites are unique compared to other health issues. Snake venom, a potent mix of proteins, can destroy tissue, paralyze muscles and impair blood clotting, often leading to severe disability which is most likely loss of limbs which were bitten or death if untreated.

“Unlike diseases caused by other agents such as viruses or bacteria where one can eliminate the causing agent, a similar approach cannot be taken for snakebites,” Ralph said.

Antivenom is the only specific treatment that can prevent or reverse many of the effects of snakebite, when given early and in the right dosage.

To produce antivenom, snake venom must be first collected, or “milked,” from live snakes kept in a specialized facility. Only one facility in India, located in Tamilnadu, harvests venom for anti-venom production in India.

The venom is then diluted and injected in small doses into animals like horses, prompting their immune systems to produce antibodies. These antibodies are then harvested, purified and processed into antivenom.

But India’s only anti-snake venom treatment targets only The Big Four snakes.

“There are over 50 venomous snake species in India,” said Gnaneshwar Ch, project lead of the Snake Conservation and Snakebite Mitigation project at the Madras Crocodile Bank Trust.

“The anti-snake venom’s limited scope means bites from less common species remain inadequately treated,” he said

Despite its importance, antivenom is also not widely available, and its cost can be prohibitive for many rural families. The gaps in stocking and distribution further worsen the issue.

While many countries produce antivenom, they tend to cater to the locally available species of snakes making it impractical to import it from other countries to India in order to solve the availability crisis.

A national action plan

The WHO has called for concerted global action to reduce deaths and disability in priority nations. In 2019, the WHO launched an international strategy for preventing and controlling snakebite, which was then regionally adapted for Southeast Asia and published in 2022.

The Indian Union Health Ministry then launched the National Action Plan for the Prevention and Control of Snakebite Envenoming (NAPSE) in March 2024. The NAPSE aligns strategically with the WHO’s global roadmap and its regional adaptation for Southeast Asia.

Many stakeholders need to join forces in order to balance snakebite mitigation with snake conservation, experts say.

“Snakes tend to be very important to every ecosystem they are found in,” said Dr. Sushil John. “If snake numbers fall, we would see an increase in rodents which the snakes keep in check by eating. They would then destroy crops and spread diseases to animals and people.”

While this strategy appears to be heading in the right direction, some experts caution that there might be barriers to implementation.

“While public hospitals may adopt the reporting system, many Indians seek private health care,” said Professor Sakthivel Vaiyapuri, a venom pharmacologist at the University of Reading in England. “Mechanisms to ensure private hospitals comply with reporting requirements are essential.”

Vaiyapuri helped work on the National Action Plan. He said health workers who are to report snakebite must understand the significance of their role which will motivate them to record the data accurately. He also said someone must verify the entered data independently to ensure accuracy. He suggests developing a mobile app to streamline data collection.

While Vaiyapuri worries about the logistics of implementing such a plan for massive surveillance, there are also other worries about unintended consequences for snakebite victims, according to Dr. Anand Zachariah, a toxicologist at CMC Vellore.

“When India made maternal deaths notifiable, many private clinics in India stopped treating high-risk pregnancies because they worried about the reporting process getting them in trouble if something went south,” said Zachariah. “I fear snakebite becoming a notifiable disease might trigger such defensive practices among physicians.”

But he admits that at this point, the fear is only theoretical; what will eventually happen remains to be seen.

“Despite the challenges, I think [the National Action Plan] is a pivotal initiative in tackling snakebite envenomation in India,” Vaiyapuri said.

“By fostering accurate data collection, promoting intersectoral collaboration and engaging communities, the plan holds significant potential to drive meaningful change — ensuring effective prevention, timely treatment and a significant reduction in snakebite-related deaths and disabilities,” Vaiyapuri said.

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