title: The interrelationship between dengue incidence and diurnal ranges of temperature and humidity in a Sri Lankan city and its potential applications.
abstract: BACKGROUND
  Temperature, humidity, and other weather variables influence dengue transmission. Published studies show how the diurnal fluctuations of temperature around different mean temperatures influence dengue transmission. There are no published studies about the correlation between diurnal range of humidity and dengue transmission.
  
  
  OBJECTIVE
  The goals of this study were to determine the correlation between dengue incidence and diurnal fluctuations of temperature and humidity in the Sri Lankan city of Kandy and to explore the possibilities of using that information for better control of dengue.
  
  
  METHODS
  We calculated the weekly dengue incidence in Kandy during the period 2003-2012, after collecting data on all of the reported dengue patients and estimated midyear populations. Data on daily maximum and minimum temperatures and night-time and daytime humidity were obtained from two weather stations, averaged, and converted into weekly data. The number of days per week with a diurnal temperature range (DTR) of >10°C and <10°C and the number of days per week with a diurnal humidity range (DHR) of >20 and <15% were calculated. Wavelet time series analysis was performed to determine the correlation between dengue incidence and diurnal ranges of temperature and humidity.
  
  
  RESULTS
  There were negative correlations between dengue incidence and a DTR >10°C and a DHR >20% with 3.3-week and 4-week lag periods, respectively. Additionally, positive correlations between dengue incidence and a DTR <10°C and a DHR <15% with 3- and 4-week lag periods, respectively, were discovered.
  
  
  CONCLUSIONS
  These findings are consistent with the results of previous entomological studies and theoretical models of DTR and dengue transmission correlation. It is important to conduct similar studies on diurnal fluctuations of humidity in the future. We suggest ways and means to use this information for local dengue control and to mitigate the potential effects of the ongoing global reduction of DTR on dengue incidence.
authors.affiliation: The Teaching (General) Hospital - Kandy, Kandy, Sri Lanka; drehelepola@gmail.com.
authors.forename: N D B
authors.initials: ND
authors.lastname: Ehelepola
authors.affiliation: Lanka Hydraulic Institute, Moratuwa, Sri Lanka.
authors.forename: Kusalika
authors.initials: K
authors.lastname: Ariyaratne
mesh_terms: D000330:Aedes / Q000821:virology; D000818:Animals; D002947:Cities; D003715:Dengue / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission; D014943:Global Health; D057232:Global Warming; D006801:Humans; D006813:Humidity; D015994:Incidence; D007303:Insect Vectors / Q000821:virology; D008962:Models, Theoretical; D013188:Sri Lanka / Q000453:epidemiology; D013696:Temperature
keywords: Aedes; Sri Lanka; climate change; dengue; diurnal range; diurnal temperature range; global warming; humidity; neglected diseases; wavelet analysis