Science chats with João Miguel Alves-Nunes about his risky experimental approach, and how it could help save lives
More than 5 million people are bitten by snakes every year, resulting in thousands of deaths and permanent disabilities. Yet despite advances in developing antivenoms, scientists still don't know why some snakes bite humans and others don't.
João Miguel Alves-Nunes has developed an unusual—and some would say insane—way to find out. The biologist at the Butantan Institute has stepped on jararacas—one of South America's most venomous and dangerous vipers— . The results of this risky experiment, published this month in Scientific Reports , could help save lives, he says.
Science spoke with Alves-Nunes about his work and why he puts himself in mortal danger for science. This interview has been translated from Portuguese and edited for clarity and length.
Q: Why did you decide to do this experiment?
A: Snake behavior has been generally neglected as a field of research, especially in Brazil. And most studies don't examine what factors make them want to bite. If you study malaria, you can research the virus that causes the disease—but if you don't study the mosquito that carries it, you will never solve the problem. Up until now, the popular wisdom was that the jararaca would only attack if you touched it or stepped on it. But that was not what we found.
Q: Why did you need to be the victim?
A: The best way to do this research is to put snakes and a human together. In this case, the human was me. We put the snakes inside a ring on the floor of our lab until they got used to it, then I stepped in wearing special protective boots. I stepped close to the snake and also lightly on top of it. I didn't put my whole weight on my foot, so I did not hurt the snakes. I tested 116 animals and stepped 30 times on every animal, totaling 40,480 steps.
Q: Did you feel safe?
A: That is a good question! I chose the protective boot based on the opinion of experienced colleagues at Butantan. They were leather boots covered in foam that went 3 centimeters above my knees. I felt 100% safe, and the jararaca bites never punctured them. However, when I was doing simulations with a rattlesnake, one punctured the boot, and I was bitten.
Thankfully, I was in the best place I could be. The Butantan Institute is a leader in antivenom development, and I was very well-assisted at its hospital. Unfortunately, I discovered that I am allergic to both antivenom and snake toxins. I had to take a 15-day medical leave.
Q: Did you reconsider working with snakes after that?
A: No, this is my passion. I love working with these animals. After the accident, I reinforced the boots so I would not be bitten again. Because of my allergy, I now avoid directly handling the snakes. I leave it to the lab technicians, and I concentrate on the experiment design and data analysis instead.
Q: What did your colleagues think when you proposed stepping on snakes?
A: It was seen as normal. It is very common practice in the study of nonvenomous animals to poke them with your finger and handle them to observe their defensive behavior. My adviser's adviser [Ivan Sazima, a biologist at the State University of Campinas] pioneered the practice of offering his legs to snakes back in 1988 . In those experiments, he did so only once and more gently, not directly touching the animals. So no one had done this in such a direct way to simulate bites like we did.
The hard part is that, after my accident, some people started to see me as reckless. And that is not true. I ran these experiments with a solid scientific base, followed the same protocol thousands of times, and had only one accident. And from that accident, a research question was born: I am now comparing the bite strength of rattlesnakes and jararacas and how resistant different materials and shoes are to them.
Q: What did you discover about snake behavior?
A: The smaller the animal, the greater the chance it will bite you. Another thing is that females are more aggressive and prone to bite, especially when they are young and during the daytime. We also found that the animals get more aggressive in hotter temperatures.
All of this is consistent with the epidemiologic data we have from snakebite hospital records. In São Paulo, it is during the summer that we have most accidents, mostly with smaller, female snakes. We also saw that it makes a difference where you touch the snake's body when you step on it. When the contact occurs on the head, the probability of a defensive bite is much higher than when you step on its midbody or tail.
Q: How can these findings help with snakebite prevention or management?
A: Local governments can't distribute antivenom to everyone everywhere. Often, it is sent to big hospitals. But some of their patients are bitten in towns where there is no antivenom available and then travel to get assistance. So, the hospital record does not necessarily reflect the place where the accidents are happening.
With our new findings, we can predict where bites may happen and plan better antivenom distribution. By combining our data with data from other studies showing snake distribution, we can identify the places where the animals are more likely to be aggressive. For example, warmer places with a higher female snake population should be a priority for antivenom distribution.
Q: Any regrets?
A: When I was bitten by the rattlesnake during the simulation, I recorded it with a camera. And what was the first thing I did? I called my mother right there. Now I have this embarrassing moment on video: me crying to my mother.
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Jararacas ( Bothrops jararaca ) are more likely to bite if a person steps near their head. João Miguel Alves-Nunes During his experiments, João Miguel Alves-Nunes discovered he's allergic to the venom of rattlesnakes like the one he's holding.
Jararacas ( Bothrops jararaca ) are more likely to bite if a person steps near their head. João Miguel Alves-Nunes During his experiments, João Miguel Alves-Nunes discovered he's allergic to the venom of rattlesnakes like the one he's holding.
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