Program of Population Biology, Ecology and Evolution, Emory University, Atlanta, Georgia, United States of America.
Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, United States of America.
PLoS Comput Biol. 2021 Jan 19;17(1):e1008627. doi: 10.1371/journal.pcbi.1008627. eCollection 2021 Jan.
Heterogeneous exposure to mosquitoes determines an individual's contribution to vector-borne pathogen transmission. Particularly for dengue virus (DENV), there is a major difficulty in quantifying human-vector contacts due to the unknown coupled effect of key heterogeneities. To test the hypothesis that the reduction of human out-of-home mobility due to dengue illness will significantly influence population-level dynamics and the structure of DENV transmission chains, we extended an existing modeling framework to include social structure, disease-driven mobility reductions, and heterogeneous transmissibility from different infectious groups. Compared to a baseline model, naïve to human pre-symptomatic infectiousness and disease-driven mobility changes, a model including both parameters predicted an increase of 37% in the probability of a DENV outbreak occurring; a model including mobility change alone predicted a 15.5% increase compared to the baseline model. At the individual level, models including mobility change led to a reduction of the importance of out-of-home onward transmission (R, the fraction of secondary cases predicted to be generated by an individual) by symptomatic individuals (up to -62%) at the expense of an increase in the relevance of their home (up to +40%). An individual's positive contribution to R could be predicted by a GAM including a non-linear interaction between an individual's biting suitability and the number of mosquitoes in their home (>10 mosquitoes and 0.6 individual attractiveness significantly increased R). We conclude that the complex fabric of social relationships and differential behavioral response to dengue illness cause the fraction of symptomatic DENV infections to concentrate transmission in specific locations, whereas asymptomatic carriers (including individuals in their pre-symptomatic period) move the virus throughout the landscape. Our findings point to the difficulty of focusing vector control interventions reactively on the home of symptomatic individuals, as this approach will fail to contain virus propagation by visitors to their house and asymptomatic carriers.
蚊虫的异质暴露决定了个体对病媒传播病原体的贡献。特别是对于登革热病毒（DENV），由于未知的关键异质性的耦合效应，量化人际与病媒接触非常困难。为了检验由于登革热疾病导致人类非家居活动减少将显著影响人群动态和 DENV 传播链结构的假设，我们扩展了一个现有的建模框架，以包括社会结构、由疾病驱动的流动性减少以及来自不同感染群体的异质传染性。与对人类无症状感染性和疾病驱动的流动性变化一无所知的基线模型相比，包括这两个参数的模型预测 DENV 爆发的可能性增加了 37%；仅包括流动性变化的模型与基线模型相比，预测增加了 15.5%。在个体水平上，包括流动性变化的模型导致无症状个体（预测由个体产生的二次病例的比例）的向外传播（R）的重要性降低（高达-62%），而代价是其家庭的相关性增加（高达+40%）。通过包括个体的叮咬适宜性与家庭中蚊子数量之间的非线性相互作用的 GAM 可以预测个体对 R 的积极贡献（超过 10 只蚊子和 0.6 个体吸引力显著增加了 R）。我们的结论是，复杂的社会关系结构和对登革热疾病的不同行为反应导致有症状的 DENV 感染的比例集中在特定地点进行传播，而无症状携带者（包括处于无症状期的个体）则将病毒传播到整个景观。我们的研究结果表明，通过有针对性地对有症状个体的家庭进行病媒控制干预来控制病毒的难度，因为这种方法将无法阻止访客和无症状携带者对其房屋的病毒传播。
