title: Assessing potential countermeasures against the dengue epidemic in non-tropical urban cities.
abstract: BACKGROUND
  Dengue is a common mosquito-borne viral disease epidemic especially in tropical and sub-tropical regions where water sanitation is not substantially controlled. However, dengue epidemics sometimes occur in non-tropical urban cities with substantial water sanitary control. Using a mathematical model, we investigate what conditions can be important for a dengue epidemic to occur in an urban city such as Tokyo, where vectors are active only in summer and there are little number of vectors around hosts.
  
  
  METHODS
  The model, which is a modified Ross-Macdonald model, consists of two sets of host-vector compartments. The two sets correspond to high-risk and low-risk areas, and only hosts can move between them. Assuming that mosquitoes have constant activity for only 90 days, we assess five potential countermeasures: (1) restricted movement between the two areas, (2) insecticide application, (3) use of repellents, (4) vector control, and (5) isolation of the infected.
  
  
  RESULTS
  The basic reproduction number R 0 and the cumulative number of infected hosts for 90 days are evaluated for each of the five countermeasures. In the cases of Measures 2-5, the cumulative number of the infected for 90 days can be reduced substantially for small R 0 even if R 0>1. Although R 0 for Measure 1 monotonically decreases with the mobility rates, the cumulative number of the infected for 90 days has a maximum at a moderate mobility rate. If the mobility rate is sufficiently small, the restricted movement effectively increases the number density of vectors in the high-risk area, and the epidemic starts earlier in the high-risk area than in the low-risk one, while the growth of infections is slow.
  
  
  CONCLUSIONS
  Measures 2-5 are more or less effective. However, Measure 1 can have the opposite effect, depending on the mobility rates. The restricted movement results in the formation of a kind of core population, which can promote the epidemic in the entire population.
authors.affiliation: Undergraduate School of Informatics and Mathematical Science, Faculty of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto, 606-8501, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Masui
authors.affiliation: Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors.forename: Itsuki
authors.initials: I
authors.lastname: Kakitani
authors.affiliation: Department of Value and Decision Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.
authors.forename: Shumpei
authors.initials: S
authors.lastname: Ujiyama
authors.affiliation: Fukoku Mutual Life Insurance Company, 2-2, Uchisaiwaicho 2-chome, Chiyoda-ku, Tokyo, 100-0011, Japan.
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Hashidate
authors.affiliation: Gunma Prefectural Institute of Public Health and Environmental Sciences, 378 Kamioki-Machi, Maebashi city, Gunma, 371-0052, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Shiono
authors.affiliation: Department of Computer Science, Ochanomizu University, 2-1-1 Ohtsuka, Bunkyo-ku, Tokyo, 112-8610, Japan. kudo.kazue@ocha.ac.jp.
authors.forename: Kazue
authors.initials: K
authors.lastname: Kudo
mesh_terms: D050936:Basic Reproduction Number; D002947:Cities; D003140:Communicable Disease Control; D003715:Dengue / Q000453:epidemiology*; D004196:Disease Outbreaks; D058872:Epidemics; D006801:Humans; D007302:Insect Repellents / Q000627:therapeutic use; D007306:Insecticides / Q000627:therapeutic use; D008962:Models, Theoretical; D012621:Seasons; D014041:Tokyo; D014505:Urban Population
chemical_list: D007302:Insect Repellents; D007306:Insecticides
keywords: Core population; Dengue mathematical model; Sensitivity analysis