title: Describing interaction effect between lagged rainfalls on malaria: an epidemiological study in south-west China.
abstract: When discussing the relationship between meteorological factors and malaria, previous studies mainly focus on the interaction between different climatic factors, while the possible interaction within one particular climatic predictor at different lag periods has been largely neglected. In this study, this issue was investigated by exploring the interaction of lagged rainfalls and its impact on malaria epidemics, which is a typical example of those meteorological variables.
  
  
  
  The weekly data of malaria cases and three climatic variables of 30 counties in southwest China from 2004 to 2009 were analysed with the varying coefficient-distributed lag non-linear model. The correlation patterns of the 6th, 9th and 12th week lags would vary over different rainfall levels at the 4th-week lag.
  
  
  
  The non-linear patterns for rainfall at different rainfall levels are distinct from each other. In the low rainfall level at the 4th week lag, the increasing rainfall may promote the transmission of malaria. However, for the high rainfall level at the 4th week lag, evidence shows that the excessive rainfall decreases the risk of malaria.
  
  
  
  This study reports for the first time that the interaction effect between lagged rainfalls on malaria exists, and highlights the importance of integrating the interaction between lagged predictors in relevant studies, which could help to better understand and predict malaria transmission.
authors.affiliation: West China School of Public Health, Sichuan University, No. 17 Section 3, South Renmin Road, 610041, Chengdu, China.
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Wu
authors.affiliation: West China School of Public Health, Sichuan University, No. 17 Section 3, South Renmin Road, 610041, Chengdu, China.
authors.forename: Zhijiao
authors.initials: Z
authors.lastname: Qiao
authors.affiliation: West China School of Public Health, Sichuan University, No. 17 Section 3, South Renmin Road, 610041, Chengdu, China.
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.affiliation: West China School of Public Health, Sichuan University, No. 17 Section 3, South Renmin Road, 610041, Chengdu, China.|Division of Infectious Disease, Key Laboratory of Surveillance and Early-Warning on Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Yu
authors.affiliation: Office for Disease Control and Emergency Response, Chinese Centre for Disease Control and Prevention, NE Pacific Street, 102206, Beijing, China.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Feng
authors.affiliation: West China School of Public Health, Sichuan University, No. 17 Section 3, South Renmin Road, 610041, Chengdu, China.
authors.forename: Xiaosong
authors.initials: X
authors.lastname: Li
authors.affiliation: West China School of Public Health, Sichuan University, No. 17 Section 3, South Renmin Road, 610041, Chengdu, China. zhaoxing731@gmail.com.
authors.forename: Xing
authors.initials: X
authors.lastname: Zhao
mesh_terms: D002681:China / Q000453:epidemiology; D002980:Climate; D006801:Humans; D015994:Incidence; D008288:Malaria / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission; D017711:Nonlinear Dynamics; D011891:Rain; D012306:Risk; D012621:Seasons; D013997:Time Factors
keywords: Interaction; Lag; Malaria; Nonlinear; Rainfall