title: Outbreaks of tularemia in a boreal forest region depends on mosquito prevalence.
abstract: BACKGROUND
  We aimed to evaluate the potential association of mosquito prevalence in a boreal forest area with transmission of the bacterial disease tularemia to humans, and model the annual variation of disease using local weather data.
  
  
  METHODS
  A prediction model for mosquito abundance was built using weather and mosquito catch data. Then a negative binomial regression model based on the predicted mosquito abundance and local weather data was built to predict annual numbers of humans contracting tularemia in Dalarna County, Sweden.
  
  
  RESULTS
  Three hundred seventy humans were diagnosed with tularemia between 1981 and 2007, 94% of them during 7 summer outbreaks. Disease transmission was concentrated along rivers in the area. The predicted mosquito abundance was correlated (0.41, P < .05) with the annual number of human cases. The predicted mosquito peaks consistently preceded the median onset time of human tularemia (temporal correlation, 0.76; P < .05). Our final predictive model included 5 environmental variables and identified 6 of the 7 outbreaks.
  
  
  CONCLUSIONS
  This work suggests that a high prevalence of mosquitoes in late summer is a prerequisite for outbreaks of tularemia in a tularemia-endemic boreal forest area of Sweden and that environmental variables can be used as risk indicators.
authors: Department of Mathematics and Mathematical Statistics, Computational Life Science Cluster, Umeå University, Sweden.
authors: Patrik
authors: P
authors: Rydén
authors: Rafael
authors: R
authors: Björk
authors: Martina L
authors: ML
authors: Schäfer
authors: Jan O
authors: JO
authors: Lundström
authors: Bodil
authors: B
authors: Petersén
authors: Anders
authors: A
authors: Lindblom
authors: Mats
authors: M
authors: Forsman
authors: Anders
authors: A
authors: Sjöstedt
authors: Anders
authors: A
authors: Johansson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002648:Child; D002675:Child, Preschool; D009033:Culicidae; D004196:Disease Outbreaks; D004199:Disease Vectors; D005604:Francisella tularensis; D006801:Humans; D015994:Incidence; D007223:Infant; D008875:Middle Aged; D012621:Seasons; D013548:Sweden / Q000453:epidemiology; D014197:Trees; D014406:Tularemia / Q000453:epidemiology* / Q000635:transmission; D014887:Weather; D055815:Young Adult