Effect of temperature, relative humidity and rainfall on dengue fever and leptospirosis infections in Manila, the Philippines.
Dengue fever (DF) and leptospirosis are serious public problems in tropical regions, especially in Manila, the Philippines. In attempting to understand the causes of DF and leptospirosis seasonality, meteorological factors have been suspected, but quantitative correlation between seasonality and meteorological factors has not been fully investigated. In this study, we investigated correlation of temporal patterns of reported numbers of laboratory-confirmed cases of both DF and leptospirosis with meteorological conditions (temperature, relative humidity, rainfall) in Manila. We used time-series analysis combined with spectral analysis and the least squares method. A 1-year cycle explained underlying variations of DF, leptospirosis and meteorological data. There was a peak of the 1-year cycle in temperature during May, followed by maxima in rainfall, relative humidity and number of laboratory-confirmed DF and leptospirosis cases. This result suggests that DF and leptospirosis epidemics are correlated not only with rainfall but also relative humidity and temperature in the Philippines. Quantifying the correlation of DF and leptospirosis infections with meteorological conditions may prove useful in predicting DF and leptospirosis epidemics, and health services should plan accordingly.
Department of Hygiene,Sapporo Medical University School of Medicine,Sapporo,Hokkaido,Japan.
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Sumi
National Reference Laboratory for HIV/AIDS,Hepatitis,and other STDs,STD/AIDS Cooperative Central Laboratory,Manila,Philippines.
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Telan
Division of Disaster-Related Infectious Disease,International Research Institute of Disaster Science,Tohoku University,Sendai,Miyagi,Japan.
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Chagan-Yasutan
Epidemiology Unit,San Lazaro Hospital,Manila,Philippines.
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Piolo
Graduate School of Health Science Studies,Kibi International University,Takahashi,Okayama,Japan.
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Hattori
Department of Hygiene,Sapporo Medical University School of Medicine,Sapporo,Hokkaido,Japan.
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Kobayashi
D003715:Dengue / Q000453:epidemiology*; D058872:Epidemics; D006801:Humans; D006813:Humidity; D007922:Leptospirosis / Q000453:epidemiology*; D008685:Meteorological Concepts; D015233:Models, Statistical; D010679:Philippines / Q000453:epidemiology; D011891:Rain; D012621:Seasons; D013696:Temperature
Dengue fever; disaster; leptospirosis; time-series analysis; weather conditions