title: The impact of rainfall and temperature on the spatial progression of cases during the chikungunya re-emergence in Thailand in 2008-2009.
abstract: BACKGROUND
  In 2008, chikungunya virus (CHIKV) re-emerged in Thailand after more than a decade of absence. Cases first appeared in the extreme southern region of the country and advanced northward approx. 300 km over the next 18 months. The spatial advance of CHIKV cases appeared to occur at two rates, initially progressing slowly and then increasing in speed. We hypothesize that climatic variation affected the transmission of CHIKV in the country.
  
  
  METHODS
  To determine the effect of climate on CHIKV transmission, we evaluated models where climate affects the transmission rate from mosquitoes to humans; extrinsic incubation period; fertility rate of mosquitoes; and the mortality rate of mosquito larvae. We compared these models to models that did not include climate effects.
  
  
  RESULTS
  The inclusion of climate data greatly improved model fit with models assuming climate affected the fertility rate of mosquitoes providing the best fit to data.
  
  
  CONCLUSIONS
  These results suggest that climatic variation contributed to the slower rate of incidence observed in March 2009. Overall, a gradient in transmission probability and mortality and fertility rates of mosquito is observed over the entire area with the most southern districts experiencing the most efficient transmission.
authors.affiliation: Biophysics Group, Department of Physics, Faculty of Science, Mahidol University, Rama VI, Bangkok 10400, Thailand.
authors.forename: Sudarat
authors.initials: S
authors.lastname: Chadsuthi
authors.affiliation: Department of Disease Control, Ministry of Public Health, Tivanond 9 Road, Nonthaburi, 11000, Thailand.
authors.forename: Sopon
authors.initials: S
authors.lastname: Iamsirithaworn
authors.affiliation: Biophysics Group, Department of Physics, Faculty of Science, Mahidol University, Rama VI, Bangkok 10400, Thailand ThEP Center, CHE, 328 Si Ayutthaya Road, Bangkok 10400, Thailand Centre of Excellence in Mathematics CHE, Sriayudhaya Rd., Bangkok 10400, Thailand.
authors.forename: Wannapong
authors.initials: W
authors.lastname: Triampo
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, 21205 USA Department of Biology, University of Florida, Gainesville, FL 32611, USA datc@ufl.edu.
authors.forename: Derek A T
authors.initials: DA
authors.lastname: Cummings
mesh_terms: D000330:Aedes / Q000821:virology*; D000818:Animals; D065632:Chikungunya Fever / Q000453:epidemiology*; D002646:Chikungunya virus / Q000472:pathogenicity*; D021821:Communicable Diseases, Emerging / Q000453:epidemiology*; D006801:Humans; D007303:Insect Vectors / Q000821:virology; D007814:Larva / Q000821:virology*; D008962:Models, Theoretical; D017720:Molecular Epidemiology; D011891:Rain; D018571:Sentinel Surveillance; D013696:Temperature; D013785:Thailand / Q000453:epidemiology; D014329:Tropical Climate
keywords: Chikungunya; Emergence; Spatial; Thailand
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