RIO DE JANEIRO — Taiza Carine da Costa got her first taste of gambling when she was just 9.

She grew up in the rundown fringes of Rio de Janeiro, where her godparents would send her down the block, a few coins in hand, to bet on a popular lottery that, though illegal, has been a staple of life in Brazil for more than a century.

The habit stuck and, as an adult, she would bet daily on the game, in which players place wagers on animals represented by sets of numbers. Like many Brazilians, whenever she dreamed of a creature, she saw it as a sign to bet on the lottery, known as “jogo do bicho” — or animal game — in Portuguese.

“If I dream, I bet,” said Costa, 37, a clothing vendor.

But, lately, Costa is turning to a different game of chance that is at her fingertips around the clock: a digital slot machine offering big rewards if she can draw three matching symbols.

Tigrinho, or Little Tiger in Portuguese, mimics a popular Chinese slots game and has led the way as mobile betting apps have exploded in popularity since Brazil legalized digital gambling in 2018. Costa plays Little Tiger every day and her gambling — and her losses — have picked up as a result. She estimates she has lost roughly $80,000 over two years on the app.

“It’s hard to stop,” she said.

Online betting games, from digital casinos to soccer wagers, have sparked a fever in Latin America’s largest nation, fueling a fierce debate — like elsewhere in the world — over how to regulate the booming industry and shield lower-income people who often pile on debt or lose big chunks of meager earnings betting.

The gambling frenzy is also threatening Brazil’s animal lottery, which has links to murderous mobs and has been an unshakable part of popular culture since it was created in Rio de Janeiro in the 1800s and took off across the country.

While decades of crackdowns have failed to stamp out the lottery and the criminal gangs that run it, the analog game now appears to be in the throes of an existential crisis as fewer Brazilians are willing to physically place bets with a local bookie.

Digital alternatives — offering bigger jackpots and infinite chances — now draw more than $23 billion in wagers each year, about 10 times more than the animal lottery, according to the Legal Games Institute, a nonprofit that studies gambling in Brazil.

While the analog game has six draws per day, online gambling is nonstop.

“The Brazilian gambler now has a casino in his pocket,” said Magno José Santos de Souza, the institute’s president.

The animal lottery, on the other hand, “hasn’t been able to renew its base,” said Luiz Antônio Simas, a Rio historian who has written a book about the game.

The game was created in the 1890s by a baron seeking to draw more visitors to his newly created zoo in the Vila Isabel neighborhood of Rio. People with admission tickets were entered into a raffle, with an animal drawn at the end of each day.

The lottery soon became more popular than the zoo itself, and similar games of chance began popping up across the city. Fearing the game would hurt government lotteries, authorities banned it three years after it was created.

But the lottery’s advance was unstoppable. Before long, bookies taking bets outside bars and newspaper stands became a fixture across Brazil, with the game reaching even the most remote corners of the Amazon rainforest.

By the 1970s, the animal lottery had grown into a multimillion-dollar business fueling bloody disputes among Rio’s mafias wrestling for territorial control. The gambling bosses eventually divvied up the city and the country into zones.

To protect their illicit dealings, lottery kingpins bribed judges, politicians and police officials. In working-class areas of Rio, they won hearts and minds by buying local soccer teams, funding lavish Carnival parades and handing out Christmas presents.

“They built this playful, fun facade,” said Fabio Corrêa, a public prosecutor in Rio de Janeiro who leads a group combating organized crime. “They wanted to create this image of good Samaritans.”

The lottery’s rules can seem daunting to newcomers. Players bet on combinations of two-, three- or four-digit numbers linked to any one of 25 animals. Wagers start at a few cents, but payoffs can reach into the thousands of dollars.

Most players, though, are not placing bets in hope of getting rich, according to Simas. “They want to win a little money for a beer at the end of the day,” he said.

While most gambling, including casinos and slot machines, is barred in Brazil, lawmakers legalized digital games but delayed drafting concrete oversight rules. Experts say the lag has opened the door for thousands of unregulated platforms, some of them fraudulent, to flood Brazil.

This echoes the experiences of countries like Britain and the United States, where legislators, eager to capture tax revenues, were quick to legalize digital gambling but were later left racing to impose regulations, said Lia Nower, director of the Center for Gambling Studies at Rutgers University.

“Most legislators don’t have a real awareness that this is potentially addictive,” Nower said.

Digital games were an instant hit in Brazil, a nation of 203 million with one of the world’s highest rates of internet use. Platforms promising a fast path out of poverty quickly gained popularity among low-income people in a country marked by deep inequality.

Colorful and childlike, the apps were often promoted by social media influencers who told followers that they could win tens of thousands in cash on sites that turned out to be rigged. (Some were later arrested, accused of tricking fans into betting on unauthorized platforms.)

Brazil’s government estimates that nearly a quarter of the population started gambling online over the past five years. Brazilians now spend about $3.5 billion each month on online wagers, with sports betting making up a huge segment in soccer-crazy Brazil, according to figures from the country’s central bank.

Rushing to bring the sector under control, Brazilian authorities began enforcing a new law this month requiring betting companies to pay a fee and comply with federal rules on fraud, responsible marketing and money laundering.

The animal lottery remains illegal, but the shift to digital betting has opened new revenue streams.

Lottery bosses are using legal betting sites to launder money amassed from illicit activities like the animal lottery, authorities say.

“They are infiltrating the digital space,” Corrêa said. “They want to give an air of legality to activities that, at the end of the day, are illegal in origin.”