Dengue fever transmission between a construction site and its surrounding communities in China

Background Due to an increase in mosquito habitats and the lack facilities to carry out basic mosquito control, construction sites in China are more likely to experience secondary dengue fever infection after importation of an initial infection, which may then increase the number of infections in the neighboring communities and the chance of community transmission. The aim of this study was to investigate how to effectively reduce the transmission of dengue fever at construction sites and the neighboring communities. Methods The Susceptible-Exposed-Infectious/Asymptomatic-Recovered (SEIAR) model of human and SEI model of mosquitoes were developed to estimate the transmission of dengue virus between humans and mosquitoes within the construction site and within a neighboring community, as well between each of these. With the calibrated model, we further estimated the effectiveness of different intervention scenarios targeting at reducing the transmissibility at different locations (i.e. construction sites and community) with the total attack rate (TAR) and the duration of the outbreak (DO). Results A total of 102 construction site-related and 131 community-related cases of dengue fever were reported in our area of study. Without intervention, the number of cases related to the construction site and the community rose to 156 (TAR: 31.25%) and 10,796 (TAR: 21.59%), respectively. When the transmission route from mosquitoes to humans in the community was cut off, the number of community cases decreased to a minimum of 33 compared with other simulated scenarios (TAR: 0.068%, DO: 60 days). If the transmission route from infectious mosquitoes in the community and that from the construction site to susceptible people on the site were cut off at the same time, the number of cases on the construction site dropped to a minimum of 74 (TAR: 14.88%, DO: 66 days). Conclusions To control the outbreak of dengue fever effectively on both the construction site and in the community, interventions needed to be made both within the community and from the community to the construction site. If interventions only took place within the construction site, the number of cases on the construction site would not be reduced. Also, interventions implemented only within the construction site or between the construction site and the community would not lead to a reduction in the number of cases in the community.

Dengue fever transmission between construction site and its surrounding communities in China

Background: Due to more mosquito habitats and the lack of basic mosquito control facilities, construction sites are more likely to have secondary cases after case importation, which may increase the number of cases in the neighborhood community and the chance of community transmission. This study aims to investigate how to effectively reduce the dengue transmission in construction sites and the neighboring communities.Methods: Susceptible-Exposed-Infectious/Asymptomatic-Recovered (SEIAR) model of human and SEI model of mosquitoes were developed to estimate the transmission of dengue virus between human and mosquitoes within the construction site and within a neighboring community, as well between them. With the calibrated model, we further estimated the effectiveness of different intervention scenarios targeting at reducing the transmissibility at different locations (i.e. construction sites and community) with the total attack rate (TAR) and the duration of the outbreak (DO).Results: A total of 102 construction site-related and 131 community-related cases of dengue were reported in our study area. Without intervention, the cases related to the construction site and the community rose to 156 (TAR: 31.25%) and 10796 (TAR: 21.59%). When cutting off the transmission route from mosquitoes to human in the community, the community cases decreased to a minimum of 33 compared with other simulated scenarios (TAR: 0.068%, DO: 60 days). If the transmission route from infectious mosquitoes in the community, and from the construction site to susceptible people on the site, was cut off at the same time, the cases in the construction site dropped to a minimum of 74 (TAR: 14.88%, DO: 66 days).Conclusions: To control the outbreak effectively for both the construction site and the community, interventions needed to be taken within the community and from the community to the construction site. If interventions were only taken within the construction site, this could not reduce the number of cases on the construction site. If interventions were taken within the construction site or between the construction site and the community, this could not lead to a reduction in the number of cases in the community.

Dengue fever transmission between construction site and its surrounding communities in China

Background: Because of the urbanization and the lack of basic mosquito control facilities, constructions sites might increase the transmission risk of dengue. For example, the outbreak in Zhanjiang Prefecture, China, 2018, started at a construction site, then spread to surrounding communities. This study aims to investigate how to effectively reduce the dengue transmission risk related to construction sites.Methods: The study was based on an outbreak of dengue fever (DF) occurred in Zhanjiang Prefecture, Guangdong Province in 2018. We simulated the transmission of dengue virus between human and mosquitoes at the construction site and in the neighboring community separately, as well between them by assuming human movement between the construction site and the neighboring community. Susceptible-Exposed-Infectious/Asymptomatic-Recovered (SEIAR) model was used for the human, while SEI model was used for the mosquitoes. We obtained the transmissibility parameters by fitting the model to observed number of incident cases before local interventions started and the coefficient of determination (R2) was used to quantify the significance of the fit. We then evaluated the effectiveness of different intervention scenarios targeting at reducing the transmissibility between different human and mosquito subpopulations at different locations (i.e. construction sites and community) quantified by the total attack rate (TAR) and duration of the outbreak (DO).Results: A total of 467 cases of dengue fever were reported in Zhanjiang Prefecture in 2018, among which 102 were located at a construction site and 131 were located in the surrounding community. The values of R2 were 0.829 (P < 0.001) and 0.878 (P < 0.001) for the construction site and the community, respectively. The modelling outcome indicated that without interventions, the number of cases on the construction site would reach to 156, yielding a total attack rate (TAR) of 31.25% (95% confidence interval [CI]: 27.18%- 35.31%). In the community, the number of the cases would be much more than the reported data and up to 10796, yielding a TAR of 21.59% (95%CI: 21.23%- 21.95%). When the transmission route from mosquitoes to people is cut off in the community, the number of cases in the community would decrease to a minimum of 33 compared with other situations we simulated, yielding a TAR of 0.068% (95%CI: 0.05%- 0.09%) and a duration of outbreak (DO) of 60 days. When the transmission route from infectious mosquitoes in the community and the construction site to susceptible people on the construction site is cut off at the same time, the number of cases in the construction site would drop to a minimum of 74, yielding a TAR of 14.88% (95%CI: 11.76%- 18.00%) and a DO of 66 days.Conclusions: Construction sites may facilitate the dengue outbreaks into neighboring communities, SEIAR-SEI model can be efficiently applied to simulate outbreaks of dengue fever. Cutting off the transmission routes and properly controlling vectors in communities is an effective measure to control this disease.