Modeling seasonal leptospirosis transmission and its association with rainfall and temperature in Thailand using time-series and ARIMAX analyses.
OBJECTIVE
To study the number of leptospirosis cases in relations to the seasonal pattern, and its association with climate factors.


METHODS
Time series analysis was used to study the time variations in the number of leptospirosis cases. The Autoregressive Integrated Moving Average (ARIMA) model was used in data curve fitting and predicting the next leptospirosis cases.


RESULTS
We found that the amount of rainfall was correlated to leptospirosis cases in both regions of interest, namely the northern and northeastern region of Thailand, while the temperature played a role in the northeastern region only. The use of multivariate ARIMA (ARIMAX) model showed that factoring in rainfall (with an 8 months lag) yields the best model for the northern region while the model, which factors in rainfall (with a 10 months lag) and temperature (with an 8 months lag) was the best for the northeastern region.


CONCLUSIONS
The models are able to show the trend in leptospirosis cases and closely fit the recorded data in both regions. The models can also be used to predict the next seasonal peak quite accurately.
Biophysics Group, Department of Physics, Faculty of Science Mahidol University, Rama VI, Ratchathewi District, Bangkok, Thailand.
Sudarat
S
Chadsuthi
Charin
C
Modchang
Yongwimon
Y
Lenbury
Sopon
S
Iamsirithaworn
Wannapong
W
Triampo
D006801:Humans; D015994:Incidence; D007922:Leptospirosis / Q000453:epidemiology / Q000635:transmission*; D008954:Models, Biological; D015999:Multivariate Analysis; D011891:Rain; D012111:Residence Characteristics; D012621:Seasons; D013696:Temperature; D013785:Thailand / Q000453:epidemiology