Columnaris disease bacteria detected in Brazil for first time, threatening farmed fish

A pathogen long confined to Asia and the United States has crossed into Brazil, where scientists have detected Flavobacterium bacteria — the cause of columnaris disease — in fish farms across three states. The discovery, published in Microbial Pathogenesis, reveals not only a geographic expansion but a biological one: the bacteria have adapted to Brazil's warm inland waters and are infecting native fish species beyond their previously known hosts. In a country where farmed fish feeds millions, the arrival of this disease sits at the intersection of global trade, ecological vulnerability, and t