Mapping African swine fever across the Indonesian archipelago using media-based surveillance

Effective disease surveillance is critical for preventing and controlling the spread of infectious diseases. Where reliable case data are scarce, non-traditional data sources like media reports offer a valuable alternative. Our study focuses on African Swine Fever (ASF), a highly contagious and lethal viral disease affecting domestic and wild pigs. Since late 2018, ASF spread rapidly across 20 Asian countries, reaching a critical point where it poses an extinction risk to the region's endemic wild pig species and cascading impacts on apex predators, rural livelihoods and the pork industry. We compiled online media articles using ASF-related keywords to describe spatio-temporal spread of ASF across Indonesia, a vast archipelago of 17,380 islands, containing seven wild pig species and supporting localized domestic pork production. Media-derived data were supplemented with expert interviews to provide additional context on ASF impacts. From September 2019–December 2023, we identified 149 media reports documenting 385,499 domestic pig deaths and 596 wild pig deaths, mostly involving forest-edge wild boar, followed by forest-dwelling bearded pig and Sulawesi warty pig. ASF was first detected in western Indonesia and subsequently spread eastwards, reaching 22 of 38 provinces within 47 months. Supplementary field data indicated possible collapses of wild pig populations in several provinces, revealing impacts not captured through media monitoring alone and underscoring the importance of integrating media monitoring data with expert interviews or citizen science. Nevertheless, our findings demonstrate the value of a low-cost, timely and non-traditional surveillance method for detecting disease outbreaks and mapping their spread in countries lacking comprehensive monitoring systems.