Analysis and spatiotemporal distribution of infectious disease early warning signals during a major flooding event: New South Wales and Queensland 2022 floods.

OBJECTIVES

Floods and climate-related events are associated with increased risk of certain infectious diseases. Japanese encephalitis virus (JEV) appeared unexpectedly for the first time on the Australian mainland in 2022 amid major floods and the occurrences may be associated. Open-source intelligence (OSINT)-based surveillance may provide early indicators of infectious disease threats during extreme weather events. The primary aim of this study was to analyse OSINT disease signals and corresponding outbreak locations surrounding the 2022 flood events.

STUDY

DESIGN

retrospective descriptive analysis.

METHODS

We extracted retrospective data from the EPIWATCH® OSINT surveillance system before, during and after 2022 flooding in New South Wales and Queensland. Spatiotemporal signal distribution and rainwater level was analysed across each state. Four time periods were analysed: pre, mid and post-flood and a 'dry' control period.

RESULTS

Of 347 signals, signals were highest in the dry period and only for COVID-19. Signals were lowest in the pre-flood period (30), increasing mid and post-flood (80 and 90, respectively), with animal disease signals peaking mid-flood (14). Spatiotemporal signal distribution suggests that disease signals predominantly appeared in areas with increased rainfall mid and post-flood. Acute gastroenteritis in humans, pythiosis in animals and Japanese encephalitis virus (JEV) in humans and animals appeared to temporally and spatially align with high rainwater levels.

CONCLUSION

OSINT-generated signals of disease in animals and humans appeared to associate with flooding as suggested by descriptive analysis. In flood-risk areas, OSINT surveillance can assist with preparedness and response to the health effects of weather events, including diarrheal and emerging infectious diseases.