Every year, some five million people will suffer snakebites, about 100,000 will die from the toxic venoms and some 400,000 people will undergo amputations and other permanent disabilities as a result of snakebite envenoming, according to World Health Organization statistics. Now, an international group of scientists and researchers say they’ve created a simulation model for predicting snakebites that could lead to reducing snakebite cases.
“The model can be used as a warning system to say when and where there’s high risk for snake bites, which is something that doesn’t really exist right now,” Eyal Goldstein of the School of Zoology at Tel Aviv University, a co-lead author of the study, tells NoCamels. “We’re the first to offer this kind of scientific development.”
While in many parts of the world snakebites are barely even acknowledged, in South Asia it is a serious problem, even a daily concern, and boasts the highest incidence of venomous snakebites in the world, according to the recent study published in PLOS Neglected Tropical Diseases.
The international study was co-led by Goldstein, Dr. Takuya Iwamura (currently at Oregon State University) and Dr. Kris Murray of Imperial College London and the School of Hygiene and Tropical Medicine in London. Other participants included researchers from the Liverpool School of Tropical Medicine, Lancaster University and the University of Kelaniya, Sri Lanka.
In 2017, the World Health Organization recognized snakebite as a “neglected tropical disease” and called on the research community to tackle the topic. In 2018, a resolution passed in the World Health Assembly to boost efforts on ways to overcome snakebite.
Goldstein, of Tel Aviv University, says he was drawn to join the global study because he likes snakes and he “was really interested in doing socio ecological modeling.”
The international research group created the first-of-its-kind interdisciplinary model for predicting snakebites, based on an improved understanding of interactions between farmers and snakes. The goal of the model was to pinpoint the probability of a snakebite at specific times of the day.
“The model tries to follow a few factors of snake behavior as well as their seasonal and daily activity patterns, and how climate affects it,” Goldstein tells NoCamels. “On the other side, we tried to follow farmers’ behaviors. So, we look at times of day and months that farmers go out to different agricultural fields. And then when we combined the data with how climate affects each side, we got some idea of what is driving snakebites.”
The researchers conducted the study in Sri Lanka, where there is a collection of extensive research and data of 30,000 envenoming snakebites, which kill approximately 400 people in this island country, every year.
The WHO explains envenoming as “a potentially life-threatening disease that typically results from the injection of a mixture of different toxins (“venom”) following the bite of a venomous snake. Envenoming can also be caused by having venom sprayed into the eyes by certain species of snakes that have the ability to spit venom as a defence measure.”
Up to 2.7 million envenomings take place annually, according to WHO reports. Farmers and livestock workers are most affected.
“Our approach is to mathematically analyze interactions between snakes and humans, with an emphasis on the ecological perspective. This is a completely new approach to understanding the mechanism that causes snakebites. Unlike most studies, which have so far focused mainly on social and economic risk factors, we chose to focus on the ecological aspects – such as snakes’ movements and habitats, the impact of climate and rainfall, and the respective behaviors of farmers and snakes – as a key to predicting potential encounters,” Dr. Iwamura said in a statement.
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According to a 2019 research study, over half of all snakebites occur in 30–50-year-old farmers and in 60-80 percent of the cases they’re bitten on their ankles and feet while out in their fields.
The new study focused on six types of snakes: cobra, Russell’s viper, saw-scaled viper (also known as carpet viper or Echis), hump-nosed viper, common krait and Ceylon krait. The data was matched with farmers who grow the three most common crops in the area: rice, tea and rubber. For example, the model can predict that the bites of Russell’s viper peak in rice fields during February and August, while the hump-nosed viper prefers rubber plantations in April and May.
“We built a first-of-its-kind interdisciplinary model, which includes the behavior patterns of both sides – snakes and humans, identifying risk factors at various times and places, and warning against them. For example, the model can differentiate between low-risk and high-risk areas, a difference that can be manifested in double the number of snakebites per 100,000 people,” says Goldstein, who became a fan of the Sri Lankan green vine snake while on the research project.
“Both snakes and people go about their business at different times of the day, in different seasons and in different types of habitats – the model captures all of this to predict encounters between people and snakes in areas where farmers are working. We then factor in the aggressiveness of different snake species to work out how likely an encounter is to result in a bite,” Dr. Murray said in a press statement.
Goldstein tells NoCamels that most countries do not have data on snakebite and envenoming cases. The team verified its information against existing data in Sri Lanka and the model proved accurate in predicting snakebite patterns in different areas and different seasons.
The plan is to implement the model in places that don’t yet have accurate snakebite data and hopefully help to predict future changes resulting from climate change – such as increased rainfall leading to greater snake activity, as well as changes in land use and habitats available to snakes.
“We will try to figure out how snake bites are going to affect farmers who choose between different adaptation strategies,” Goldstein tells NoCamels. “We would also like to see this module adapted to more places.”
Next steps include epidemiological studies of snakebite, herpetological conservation studies and implementing the model in places that don’t yet have accurate snakebite data.
“Our model can help focus the efforts of snakebite reduction policies, and serve as a tool for warning, raising awareness and saving human lives. Moreover, we regard this study as a first stage in a broader project. In the future we intend to develop more complex models of encounters between humans and wildlife, to support both public health and nature preservation policies in the real world,” says Iwamura.
Viva Sarah Press is a journalist and speaker. She writes and talks about the creativity and innovation taking place in Israel and beyond. www.vivaspress.com