Groussin’s Adventure in Paraguay

When I first met Groussin in late October 2024, he had just completed a marathon journey of over 20 hours from Kiel, Germany, to Asunción, Paraguay. This trip marked his conservancy’s second expedition in South America. His partner, Poyet, who was six months pregnant with their second child, was not with him. “Please,” he urged me, “Mathilde is the real hero here. She’s handled most of the planning for this trip. The only reason I’m here is because she’s at home getting ready to have our baby.”

Groussin and his team had plans to travel another ten hours to the Cerro Itá Guazú Indigenous reservation, located near the border with Brazil. There, they intended to collect blood, saliva, feces, and vaginal secretions from volunteers. However, they faced a significant hurdle, as most of their necessary equipment—the chemicals, containers, and a highly specialized storage tank, along with around 1,000 labeled test tubes—was stuck in customs due to a paperwork issue. It was uncertain when this glitch would be resolved, leaving their Paraguayan collaborators anxious due to the time and money invested. “We’re quite possibly in a tough spot,” Walter J. Sandoval Espínola, a microbiologist from the National University of Asunción, said, as he and a few junior scientists gathered in front of a whiteboard that dominated his lab.

Surprisingly, Groussin appeared calm. “We’ll figure something out,” he remarked with a shrug. “We’ve definitely been through worse.” A few hours later, the team had managed to buy, borrow, or improvise much of what they needed, including a portable liquid nitrogen tank, several hundred test tubes that now required relabeling, and various lidded plastic bowls for study participants to use. These bowls were see-through, so they would need lining—perhaps with paper or foil—to ensure privacy.

“People can be shy about their poop,” Groussin noted. “If the containers are clear, they might hesitate to submit samples.” He raised other valid concerns as well, detailing how they’d need to ensure a woman’s consent was sufficient for taking vaginal swabs, especially since they had encountered situations where men objected. Additionally, they needed permission from tribal leaders before disposing of any remaining feces. “Leaving it behind wouldn’t be sanitary,” he explained, “but taking it can be complicated. Some elders have expressed fears about us engaging in witchcraft.”