Year in surveillance

Hantavirus in Chile — 1997

Aysén ratada — bamboo mass-flowering triggers explosive rodent and Andes virus surge

Overview

In 1997, the Aysén Region of southern Chile experienced a ratada — a mass-flowering and seeding event in native Patagonian bamboo (Chusquea species) that creates a temporary food bonanza for rodents. Long-tailed pygmy rice rat populations multiplied dramatically over subsequent months, sharply increasing human exposure to Andes virus. The 1997 Aysén ratada was followed by a significant outbreak of hantavirus pulmonary syndrome and entered the public-health literature as the textbook example of ecology-driven hantavirus risk in southern South America. Chilean surveillance protocols for subsequent ratada events were strengthened in its wake.