Google can track the dengue fever hubs by monitoring search patterns and help the heath officials prepare for outbreaks.

Online surveillance over dengue-related search by users in Bolivia, Brazil, India, Indonesia and Singapore can develop an early-warning system, Google said on its official blog.

Delay in bureaucratic actions and detection can take weeks , web search query data are available real time.

Using the dengue case count data provided by Ministries of Health and the World Health Organization, we're able to build a model that offers near real-time estimates of dengue activity based on the popularity of certain search terms, writes Google software engineer Vikram Sahai in the blog.

Google developed an early warning system for flu outbreak by keeping track of users searching for information about the virus in 2009.

The project aimed at developing online awareness for dengue was developed together with Boston's Children's Hospital and Harvard Medical School.

The methodology for the project, as mentioned in the article for the Public Library of Science's journal on neglected tropical diseases, says Bolivia, Brazil, India, Indonesia and Singapore were chosen for analysis based on available data and adequate search volume.

For each country, a univariate linear model was built by fitting a time series of the fraction of Google search query volume for specific dengue-related queries from that country against a time series of official dengue case counts for a time-frame within 2003–2010. The specific combination of queries used was chosen to maximize model fit. Spurious spikes in the data were also removed prior to model fitting. The final models, fit using a training subset of the data, were cross-validated against both the overall dataset and a holdout subset of the data. All models were found to fit the data quite well, with validation correlations ranging from 0.82 to 0.99, goes the methodology behind the project.

We hope the early warning provided by Google Dengue Trends helps health officials and the public prepare for potential dengue outbreaks, writes Sahai.