Google Trends predicts present and future plague cases during the plague outbreak in Madagascar: insights and implications from an infodemiological study.

BACKGROUND: Plague is a highly infectious zoonotic disease caused by the bacillus Yersinia pestis. Three major forms of the disease are known: bubonic, septicemic, and pneumonic plague. Though being strictly related to past history, plague still represents a global public health concern. Cases of plague continue, indeed, to be reported worldwide. In the last months, pneumonic plague cases have been reported in Madagascar. However, despite such long-standing and rich history, it is rather difficult to get a comprehensive overview of the general situation. Within the framework of e-health, in which people more and more surf the Internet looking for health-related material, new information and communication technologies (ICTs) could enable researchers to get a wealth of data, which could complement traditional surveillance of infectious diseases.

OBJECTIVE: In the current work, we aimed to assess public reaction regarding the recent plague outbreak in Madagascar by quantitatively characterizing this interest.

METHODS: We captured public interest by Google Trends (GT) and correlated it to epidemiological "real-world" data (in terms of incidence rate and spread pattern).

RESULTS: Statistically significant positive correlations were found between GT search data and confirmed (R2=0.549), suspected (R2=0.265) and probable (R2=0.518) cases. From a geospatial standpoint, plague-related GT queries were concentrated in Toamasina (100%), Toliara (68%), and Antananarivo (65%). Concerning the forecasting models, the 1-day lag model was selected as the best regression model.

CONCLUSIONS: This earlier digital reaction could potentially contribute to better management of outbreak, for example, by designing ad hoc interventions that could contain the infection both locally and at international level, reducing its spreading.