On the outskirts of São Paulo, several secure serpentariums sit in forested parkland. They contain some of the most venomous creatures on earth and provide the fuel for Latin America’s biggest antivenom manufacturing and research facility.

In one corner of the grounds, huts on stilts house five of Brazil’s most endangered snakes. One, the golden lancehead, is so rare that poachers asked $20,000 for a single specimen. It is found only on a tiny uninhabited island off the South Atlantic coast.

Nearby, inside the campus’s oldest building, a dip worn into the stone floor shows wear from the original serum-producing horses housed here over a century ago. Around it hang old scientific drawings and shelves stacked with journals bound in snakeskin.

This is Brazil’s Butantan Institute. Founded in 1901 to fight an outbreak of bubonic plague, it now produces almost all of the country’s antivenoms, supplying at least 350,000 vials annually. It is part of a public health system that has made snakebite in Latin America far less deadly than almost anywhere else in the world.

Now, having spent over a century perfecting antivenom at home, Brazil is expanding its global impact – sharing not just its lifesaving sera, but its world-leading snake research.

More than five million people are bitten by snakes around the world each year. Between 82,000 and 138,000 die, while roughly three times as many suffer amputations or permanent disability, according to the World Health Organization (WHO).

The burden falls heaviest on poor rural communities in Asia (up to two million bites annually) and Africa (around 500,000), where farmers, women and children walk through dense vegetation without protective clothing or access to nearby hospitals.

Across the Americas, the incidence of bites is far smaller. Some 57,000 are bitten by snakes each year, with Brazil accounting for over 30,000, according to the country’s health ministry.

But what stands out is the survival rate. According to the Pan American Health Organization (Paho), the region’s fatality rate is just 0.6 per cent – compared to up to 12 per cent in some  rural regions of Africa.

Latin American snakes are no less dangerous. Venom from bothrops, a genus of the pit viper known locally as “jaracas”, can dissolve blood vessels, stop clotting and cause severe flesh rot or necrosis. Bites from the viper account for up to 90 per cent of reported envenomings each year in Brazil.

Brazil’s constitution legally obliges the state to provide treatment regardless of cost, resulting in antivenom having come to be seen as an essential public right, rather than a commodity for profit.

For poor rural workers who cannot afford treatment, receiving free antivenom quickly is what prevents a bite from becoming fatal.

Regional biology helps too. Unlike in Asia or Africa, where dozens of disparate snake families complicate treatment, the dominance of the Bothrops in Brazil makes life easier.

It means that rural clinics only need to stock a few versatile antivenoms rather than dozens of hyper-specialised ones. The Butantan Institute makes roughly 400,000 vials annually, more than enough to meet demand.

Yet even such a well-designed system struggles with the country’s unforgiving geography.

Covering nearly half of Brazil, the Amazon rainforest has vast roadless expanses where travel relies on slow wooden boats. For isolated communities, reaching a stocked clinic can take 12 to 24 hours – often beyond the critical window to prevent amputation or death.

Part of the challenge lies in the treatment itself. Traditional liquid antivenom must be administered intravenously under strict medical supervision due to the risk of acute allergic reactions. Crucially, it also requires an unbroken cold chain.

When exposed to tropical heat, the therapeutic proteins quickly denature and clump together. This renders the serum useless or, in the worst cases, dangerous.

To overcome this, Brazil is increasingly deploying freeze-dried (lyophilised) antivenoms. 

Though more expensive and complex to produce, these powder formulations withstand high heat and remain stable for years without cooling, needing only sterile water to reconstitute them for use. 

The centuries-old process of creating antivenom is complex and relies on a method barely changed since its invention. 

Pioneered in 1895 by French physician Albert Calmette in Saigon (now Ho Chi Minh), Vietnam, the process begins by manually milking live snakes for their venom.

Small, non-lethal doses are then injected into horses over several months, prompting their immune systems to produce high concentrations of specialised antibodies. 

Once levels peak, blood is drawn from the horses, and the plasma is separated and purified into concentrated vials of serum.

The new breakthrough lies in a technique of lyophilisation, or freeze drying, in which the liquid serum is converted into a heat-stable powder. 

The antivenom is subjected to a temperature of -40 C inside a deep vacuum chamber. It leaves a fine powder that prevents antibody proteins from degrading or clumping.

Sealed in airtight vials, the powder can sit without refrigeration for years, needing only a splash of sterile water to become an active intravenous antivenom in seconds.

Brazil’s antivenom infrastructure was the vision of one 19th-century physician.

The Institute’s origins trace back to 1899, when an outbreak of bubonic plague struck Santos, a major port city in the state of São Paulo, threatening Brazil’s coffee-dependent economy.

Officials turned to Dr Vital Brazil, a pioneering physician who set up a makeshift laboratory inside an old stable at Fazenda Butantan, a 400-hectare property outside the capital.

To test how the plague spread, he famously let himself be bitten by mosquitoes; when he didn’t fall ill, he (correctly) concluded rodents and fleas, rather than insects,  were the vectors.

By 1901, the stables had officially become the Butantan Institute. The research facility was modelled on Paris’s Pasteur Institute – the “global gold-standard reference” of the era, according to Suzana Fernandes, director of the Butantan Center for Cultural Development.

“It was a model adapted here in Brazil for research, production, and the popularisation of science,” she says.

With the plague contained, Dr Brazil turned to a slower, but equally lethal threat: the pit vipers killing thousands of farmers across São Paulo’s booming coffee fields.

While European authorities insisted a single antivenom could treat any bite, Dr Brazil proved serum must be tailored to the snake’s specific genus – a principle that remains foundational to antivenom science today.

To produce these species-specific antivenoms at scale, he devised an unconventional public barter network. 

The Institute shipped wooden boxes and snake hooks to rural communities. In return, farmers captured live snakes and loaded them onto trains bound for São Paulo, where conductors guarded the locked crates in dedicated carts.

To seal the bargain, the Institute rewarded those participating with free vials of lifesaving antivenom. Between 1901 and 1977, the railway network delivered over 1.1 million live snakes to Butantan.

More than a century later, new snake lineages are still emerging from Brazil’s vast ecosystems. In 2022, for example, researchers formally described Bothrops jabrensis, a distinct species of pit viper discovered in the high-altitude forests of northeastern Paraíba.

Behind an unmarked door lies Butantan’s Herpetological Collection – one of Latin America’s most important archives of preserved reptiles.

Dr Felipe Grazziotin, its curator, leads the way inside, revealing floor-to-ceiling shelves lined with stoppered glass jars. Suspended inside in pale-yellow ethanol are serpents, scorpions, and spiders – their intricate scale patterns and beady eyes frozen mid-glare.

Each jar has a handwritten label – a record of where a species was found, when and by whom. But in 2010, that priceless history was almost wiped out when a devastating fire swept through the Institute, severely damaging its collections.

Out of what was then the world’s largest snake collection – totaling nearly 100,000 specimens – scientists managed to salvage only 15,000 to 20,000. Most of the glass jars shattered in the intense heat and firefighting efforts.

“We lost more than 100 years of history about snakes in Brazil,” Dr Grazziotin says, adding that the news nearly brought him to tears at the time. “Without the label, a specimen loses its scientific meaning for us. We need to know exactly where it came from”.

He walks to the end of one of the solid metal shelves and spins a large mechanical wheel. With a low hum, the wall of jars parts down the middle, opening a new aisle.

As he steps between the banks, Dr Grazziotin points out that despite the devastation of 2010, certain parts of the collection survived the blaze remarkably intact.

“It was purely down to where they were stored in the building,” he says, gesturing toward a meticulously ordered section of jars containing some 8,000 South American rattlesnakes – an entire species’ record preserved against the odds.

Losing a century of history forced Butantan to completely rethink how it preserves its science.

Since the fire, the collection has been rebuilt inside a state-of-the-art facility with fire-suppression gas systems and shatterproof plastic containers.

In a nearby room, Dr Grazziotin proudly gestures toward a new $2 million (£1.5 million) machine: a sleek Micro-CT scanner, the only one of its kind in South America, he says.

Rather than dissecting rare or historical specimens, it creates non-invasive “digital slices” of snake skulls and internal organs, producing detailed 3D models that can then be analysed online.

The ultimate goal, Dr Grazziotin adds, is to “digitise” the entire 120-year collection into an open-access platform.

The Butantan team is also building a network across Latin America, as well as partnerships with Portuguese-speaking African nations, including Angola and Mozambique.

“We share a language and shared experiences,” Dr Grazziotin says, lifting a nearly two-metre snake from its container. “We are bringing colleagues here to work alongside us, conducting fieldwork over there, and helping them build their own national collections”.

“The idea is to reduce regional disparities,” he adds. “If we can put all the information in our collection online, we can help scientists anywhere in the world”

Protect yourself and your family by learning more about Global Health Security