Forecasting HFMD Cases Using Weather Variables and Google Search Queries in Sabah, Malaysia

Abstract

HFMD is a viral-mediated infectious illness of increasing public health importance. This study aimed to develop a forecasting tool utilizing climatic predictors and internet search queries for informing preventive strategies in Sabah, Malaysia. HFMD case data from the Sabah State Health Department, climatic predictors from the Malaysia Meteorological Department, and Google search trends from the Google trends platform between the years 2010-2018 were utilized. Cross-correlations were estimated in building a seasonal auto-regressive moving average (SARIMA) model with external regressors, directed by measuring the model fit. The selected variables were then validated using test data utilizing validation metrics such as the mean average percentage error (MAPE). Google search trends evinced moderate positive correlations to the HFMD cases (r_0-6weeks: 0.47-0.56), with temperature revealing weaker positive correlations (r_0-3weeks: 0.17-0.22), with the association being most intense at 0-1 weeks. The SARIMA model, with regressors of mean temperature at lag 0 and Google search trends at lag 1, was the best-performing model. It provided the most stable predictions across the four-week period and produced the most accurate predictions two weeks in advance (RMSE = 18.77, MAPE = 0.242). Trajectorial forecasting oscillations of the model are stable up to four weeks in advance, with accuracy being the highest two weeks prior, suggesting its possible usefulness in outbreak preparedness.

Keywords: ARIMA; EV71; Google trends; coxsackie; meteorology; prediction model.

Figure 1

HFMD cases, temperature, rainfall, humidity, trends, and incidence in Sabah 2010–2018. (a) Mean temperature, (b) maximum temperature, (c) minimum temperature, (d) mean rainfall, (e) mean relative humidity, (f) Google search trends, (g) HFMD cases, and (h) spatial distribution of incidence.

Figure 2

Predictions of HFMD compared to actual HFMD cases; (a) actual against 1-week advance predictions of HFMD cases, 2017–2018, using SARIMA model, (b) actual against 1-week advance predictions of HFMD cases, 2017–2018, using SARIMA with external regressors model, (c) actual against 2-week advance predictions of HFMD cases, 2017–2018, using SARIMA model, (d) actual against 2-week advance predictions of HFMD cases, 2017–2018, using SARIMA with external regressors model, (e) actual against 3-week advance predictions of HFMD cases, 2017–2018, using SARIMA model, (f) actual against 3-week advance predictions of HFMD cases, 2017–2018, using SARIMA with external regressors model, (g) actual against 4-week advance predictions of HFMD cases, 2017–2018, using SARIMA model, and (h) actual against 4-week advance predictions of HFMD cases, 2017–2018, using SARIMA with external regressors model.