Host outdoor exposure variability affects the transmission and spread of Zika virus: Insights for epidemic control

Abstract

BackgroundZika virus transmission dynamics in urban environments follow a complex spatiotemporal pattern that appears unpredictable and barely related to high mosquito density areas. In this context, human activity patterns likely have a major role in Zika transmission dynamics. This paper examines the effect of host variability in the amount of time spent outdoors on Zika epidemiology in an urban environment.Methodology/Principal findingsFirst, we performed a survey on time spent outdoors by residents of Miami-Dade County, Florida. Second, we analyzed both the survey and previously published national data on outdoors time in the U.S. to provide estimates of the distribution of the time spent outdoors. Third, we performed a computational modeling evaluation of Zika transmission dynamics, based on the time spent outdoors by each person. Our analysis reveals a strong heterogeneity of the host population in terms of time spent outdoors–data are well captured by skewed gamma distributions. Our model-based evaluation shows that in a heterogeneous population, Zika would cause a lower number of infections than in a more homogenous host population (up to 4-fold differences), but, at the same time, the epidemic would spread much faster. We estimated that in highly heterogeneous host populations the timing of the implementation of vector control measures is the major factor for limiting the number of Zika infections.Conclusions/SignificanceOur findings highlight the need of considering host variability in exposure time for managing mosquito-borne infections and call for the revision of the triggers for vector control strategies, which should integrate mosquito density data and human outdoor activity patterns in specific areas.

Cemeteries in Miami-Dade County, Florida are important areas to be targeted in mosquito management and control efforts

“…Furthermore, as in other occupations such as in the construction workforce, cemetery workers that are responsible for landscaping and general maintenance spent a disproportional amount of time outdoors and are, therefore, subjected to vector mosquito bites being at a higher risk of being exposed to arboviruses [57][58][59].…”

Fighting the Bite during Pandemics: Florida Mosquito Control District Capabilities during the COVID-19 crisis

“…There is no questions that mosquito-borne diseases pose a special challenge to public health practitioners and mosquito control districts [1][2][3], owing to their complex nature (biological transmission complexity) [4], and potential to transmit infectious agents that can lead to mosquito-borne diseases, such as malaria, dengue fever, chikungunya, Zika fever, and West Nile fever [5]. In Florida, Aedes and Culex continue to be major vector genera [6][7][8], with the State of Florida having been ground-zero for local transmission of Zika and Dengue viruses [9], and is in close proximity to Latin American where viruses such as Zika and dengue viruses are endemic [2,10].…”

Consensus and conflict among ecological forecasts of Zika virus outbreaks in the United States

“…Other potential explanations for the limited spread of Zika through the United States are more social or socioecological in nature. In developed countries, household exposure is often secondary to outdoor exposure for Aedes, and in Miami-Dade county, it has been suggested that heterogeneity in outdoor exposure could have produced a much smaller, faster epidemic 38 . Other plausible explanations include better access to health care, preemptive vector control as part of Zika preparedness efforts, and significant fine-scale heterogeneity limiting mosquito populations in well populated areas (a factor that some models can accommodate 39 , but niche models at the global scale do not).…”