On a muggy evening in a favela on the outskirts of São Paulo, a child screams. Her foot, moments ago tucked into a sandal, is now pulsing with pain. She’s been stung. Again. And she’s not alone.

Across Brazil, scorpions are slipping into homes, hiding in shoes, lurking in drains — and stinging at an unprecedented rate. Researchers now say the country is facing a rapidly escalating public health crisis, one fueled by climate change, unplanned urban growth, and the unassuming resilience of a creature more ancient than the dinosaurs.

“The numbers showed us that in the future the problem will be bigger than it is now,” said Dr. Manuela Berto Pucca, a venom expert at São Paulo State University and lead author of a recent study in Frontiers in Public Health.

550 stings stings per day

Brazil recorded more than 1.17 million scorpion stings from 2014 to 2023, according to government data. In that time, annual reports surged by more than 155% — from 66,986 cases in 2014 to over 170,000 in 2023. And the trend isn’t slowing. The researchers project over two million new cases between 2025 and 2033.

While the raw numbers are alarming, they likely underestimate the real toll. Many victims, especially in rural or underserved areas, treat themselves at home or never report the incident. “The real scale of this issue is likely far greater than the recorded statistics suggest,” the researchers wrote.

The rise in stings is closely linked to environmental and societal shifts. As Brazil’s cities sprawl — often rapidly and haphazardly — scorpions are finding ideal new habitats. Cracks in walls, piles of construction debris, and open sewers all provide ample shelter. The cities also offer a buffet of prey: cockroaches, spiders, and other invertebrates that flourish in poorly managed waste.

“Urbanisation in Brazil has profoundly reshaped ecosystems,” Pucca told The Guardian. “Cities unintentionally offer everything scorpions need: plenty of shelter, consistent warmth, and a reliable food supply.”

Among the most dangerous is Tityus serrulatus, the yellow scorpion, which thrives in these urban environments. Females of this species reproduce through parthenogenesis — meaning no mate is required — and can survive for over a year without food. With no natural predators in city sewers, their numbers can surge quickly.

A Growing Threat

Although most stings are not fatal, they are far from benign. Victims typically experience searing pain, redness, tingling, and nausea. More serious cases can involve muscle spasms, heart arrhythmias, and even pulmonary edema. In children and the elderly, a single sting can be deadly.

“Children and the older adults are especially vulnerable due to their reduced capacity to withstand the rapid and overwhelming effects of the venom,” the study noted.

In 2024 alone, preliminary data shows nearly 200,000 scorpion stings and 133 deaths, which are more fatalities than those caused by snakes. Roughly 0.1% of reported cases end in death. But those who survive may still suffer lasting consequences — especially in regions where antivenom is not always accessible or where hospitals are overwhelmed.

“If someone is stung, don’t wait for symptoms to worsen — go to the nearest healthcare facility immediately,” urged co-author Prof. Eliane Candiani Arantes from the University of São Paulo.

Brazil’s public health system offers free treatment for scorpion stings, and antivenom is stocked at some emergency centers. But coverage is uneven, especially in the country’s sprawling and often underfunded urban peripheries.

The researchers used time-series forecasting (specifically the ARIMA model) to predict how scorpionism — defined as illness resulting from scorpion stings — might evolve. Their model suggests that by 2033, annual cases could climb to nearly 275,000, with hotspots in the Southeast and Northeast regions.

Not Just Brazil

Though Brazil is the epicenter of this scorpion swarm, this is not a uniquely Brazilian problem. Neighboring countries like Paraguay, Bolivia, Venezuela, and Mexico are experiencing similar surges. The same species are expanding their range as climate change reshapes the landscape. Rising temperatures and increased humidity — conditions in which many scorpions thrive — are making new areas hospitable to these arachnids.

In Europe, more than 35 species of scorpions have been identified, though population trends remain poorly studied. There’s little indication of an impending crisis, but experts warn that surveillance and prevention should not be neglected.

“The numbers are much higher than I would expect,” said Dr. Manuela González-Suárez, an ecologist at the University of Reading, who was not involved in the study. “This is a significant increase.”

Still, she cautioned against alarmism. “Many people who are stung do not have severe or lethal reactions and mortality rates are relatively low compared with, for example, those due to road accidents or violent crimes.”

For all the fear they inspire, scorpions are not inherently aggressive. They sting defensively when they feel threatened. And ecologically, they play vital roles, controlling pests like cockroaches and helping to maintain balance in their ecosystems.

Yet the conditions humans have created — urban chaos, poor sanitation, warming climates — are pushing this balance out of alignment.

Prevention, experts say, is the best defense. Keeping homes clean, sealing up cracks and drains, and avoiding clutter are all effective deterrents. Most importantly, awareness is key.

The findings appeared in the journal Frontiers in Public Health.