Coordination among neighbors improves the efficacy of Zika control despite economic costs

Abstract

21Background 22 Emerging mosquito-borne viruses like Zika, dengue, and chikungunya pose a major threat to 23 public health, especially in low-income regions of Central and South America, southeast Asia, 24 and the Caribbean. Outbreaks of these diseases are likely to have long-term social and economic 25 consequences due to Zika-induced congenital microcephaly and other complications. Larval 26 control of the container-inhabiting mosquitoes that transmit these infections is an important tool 27 for mitigating outbreaks. However, metapopulation theory suggests that spatiotemporally uneven 28 larvicide treatment can impede control effectiveness, as recolonization compensates for mortality 29 within patches. Coordinating the timing of treatment among patches could therefore substantially 30 improve epidemic control, but we must also consider economic constraints, since coordination 31 may have costs that divert resources from treatment. 32 Methodology/Principle Findings 33To inform practical disease management strategies, we ask how coordination among neighbors 34 in the timing of mosquito control efforts influences the size of a mosquito-borne infectious 35 disease outbreak under the realistic assumption that coordination has costs. Using an 36 SIR/metapopulation model of mosquito and disease dynamics, we examine whether larvicide 37 treatment triggered by surveillance information from neighboring patches reduces human 38 infections when incorporating coordination costs. We examine how different types of 39 coordination costs and different surveillance methods jointly influence the effectiveness of larval 40 control. We find that the effect of coordination depends on both costs and the type of 41 surveillance used to inform treatment. With epidemiological surveillance, coordination improves 3 42 disease outcomes, even when costly. With demographic surveillance, coordination either 43 improves or hampers disease control, depending on the type of costs and surveillance sensitivity. 44 Conclusions/Significance 45 Our results suggest coordination among neighbors can improve management of mosquito-borne 46 epidemics under many, but not all, assumptions about costs. Therefore, estimating coordination 47 costs is an important step for most effectively applying metapopulation theory to strategies for 48 managing outbreaks of mosquito-borne viral infections. 49 Author Summary 50 Mosquito-borne viruses, such as Zika, are an urgent public health threat, particularly in tropical, 51 low-income regions. Vector control, the main strategy for combatting outbreaks, can be 52 challenging because the urban-adapted, container-breeding mosquitoes that transmit these 53 viruses often exhibit metapopulation dynamics, where mortality in one population is 54 compensated by migration from neighboring populations. The timing and spatial distribution of 55 vector control efforts can therefore have a large impact on their efficacy. Using a model of virus 56 transmission and vector population dynamics, we demonstrate that local mosquito c...