In Puerto Rico, during October 1985, tropical storm Isabel caused widespread flooding, landslides, and collapsing of bridges. A maximum of 180 persons died, including an estimated 127 at a landslide where the majority (78%) of deaths resulted from traumatic injury. Approximately 3,000 homes were damaged with 4,400 persons temporarily displaced into 44 shelters. A shelter surveillance system was established to monitor 19 acute and chronic conditions in 28 shelters during a 5‐week period. Trend analysis trends of selected reportable communicable diseases in the general community revealed no changes attributable to the disaster in the 12 most severely affected municipalities. In these municipalities, the number of persons using the scheduled outpatient clinics after the disaster decreased significantly, but the mean daily number of emergency room visits did not show significant change. Analysis of surveillance data showed that no infectious disease outbreaks had occurred in the shelters. The post‐impact health consequences resulting from this widespread flooding were minimal. Even so, disease surveillance remains essential for efficacious resource allocation and prevention strategies. Copyright © 1990, Wiley Blackwell. All rights reserved
