title: Effectiveness of Large-Scale Chagas Disease Vector Control Program in Nicaragua by Residual Insecticide Spraying Against Triatoma dimidiata.
abstract: Chagas disease is one of the most serious health problems in Latin America. Because the disease is transmitted mainly by triatomine vectors, a three-phase vector control strategy was used to reduce its vector-borne transmission. In Nicaragua, we implemented an indoor insecticide spraying program in five northern departments to reduce house infestation by Triatoma dimidiata. The spraying program was performed in two rounds. After each round, we conducted entomological evaluation to compare the vector infestation level before and after spraying. A total of 66,200 and 44,683 houses were sprayed in the first and second spraying rounds, respectively. The entomological evaluation showed that the proportion of houses infested by T. dimidiata was reduced from 17.0% to 3.0% after the first spraying, which was statistically significant (P < 0.0001). However, the second spraying round did not demonstrate clear effectiveness. Space-time analysis revealed that reinfestation of T. dimidiata is more likely to occur in clusters where the pre-spray infestation level is high. Here we discuss how large-scale insecticide spraying is neither effective nor affordable when T. dimidiata is widely distributed at low infestation levels. Further challenges involve research on T. dimidiata reinfestation, diversification of vector control strategies, and implementation of sustainable vector surveillance.
authors.affiliation: School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan; Chagas Disease Control Project in Nicaragua, Japan International Cooperation Agency, Managua, Nicaragua; Department of Disease Prevention, Ministry of Health, Managua, Nicaragua; Fuji Environmental Service Inc., Saitama, Japan yoshiokakota@gmail.com.
authors.forename: Kota
authors.initials: K
authors.lastname: Yoshioka
authors.affiliation: School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan; Chagas Disease Control Project in Nicaragua, Japan International Cooperation Agency, Managua, Nicaragua; Department of Disease Prevention, Ministry of Health, Managua, Nicaragua; Fuji Environmental Service Inc., Saitama, Japan.
authors.forename: Jiro
authors.initials: J
authors.lastname: Nakamura
authors.affiliation: School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan; Chagas Disease Control Project in Nicaragua, Japan International Cooperation Agency, Managua, Nicaragua; Department of Disease Prevention, Ministry of Health, Managua, Nicaragua; Fuji Environmental Service Inc., Saitama, Japan.
authors.forename: Byron
authors.initials: B
authors.lastname: Pérez
authors.affiliation: School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan; Chagas Disease Control Project in Nicaragua, Japan International Cooperation Agency, Managua, Nicaragua; Department of Disease Prevention, Ministry of Health, Managua, Nicaragua; Fuji Environmental Service Inc., Saitama, Japan.
authors.forename: Doribel
authors.initials: D
authors.lastname: Tercero
authors.affiliation: School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan; Chagas Disease Control Project in Nicaragua, Japan International Cooperation Agency, Managua, Nicaragua; Department of Disease Prevention, Ministry of Health, Managua, Nicaragua; Fuji Environmental Service Inc., Saitama, Japan.
authors.forename: Lenin
authors.initials: L
authors.lastname: Pérez
authors.affiliation: School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan; Chagas Disease Control Project in Nicaragua, Japan International Cooperation Agency, Managua, Nicaragua; Department of Disease Prevention, Ministry of Health, Managua, Nicaragua; Fuji Environmental Service Inc., Saitama, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Tabaru
mesh_terms: D000818:Animals; D014355:Chagas Disease / Q000517:prevention & control*; D003365:Costs and Cost Analysis; D006798:Housing; D006801:Humans; D007300:Insect Control / Q000191:economics / Q000379:methods*; D007303:Insect Vectors / Q000469:parasitology; D007306:Insecticides / Q000191:economics; D009527:Nicaragua / Q000453:epidemiology; D015397:Program Evaluation; D014224:Triatoma / Q000469:parasitology
chemical_list: D007306:Insecticides