Late last month, something extraordinary happened at the edge of the rainforest in Acre, Brazil. Members of an uncontacted Amazonian tribe voluntarily approached scientists from the Brazilian government, Science magazine reports. This is the first time in decades that an uncontacted community chose to meet with outsiders.

Unfortunately, although peaceful, the encounter wasn't without its problems. FUNAI, Brazil's Indian protection agency, recently announced that some of the tribespeople caught a flu. For people who have never encountered flu viruses, such infections can be deadly. It's not clear whether the tribespeople got sick before or after meeting scientists, but FUNAI said once the agency realized what had happened, a medical team treated the sick tribal members and gave them flu shots. Then the members decided to return to the forest. Outside researchers are now worried the sick tribesmembers weren't treated in time to prevent them from infecting others in their village, Science reports.