Vector-borne disease risk indexes in spatially structured populations

Abstract

There are economic and physical limitations when applying prevention and control strategies for urban vector borne diseases. Consequently, there are increasing concerns and interest in designing efficient strategies and regulations that health agencies can follow in order to reduce the imminent impact of viruses like Dengue, Zika and Chikungunya. That includes fumigation, abatization, reducing the hatcheries, picking up trash, information campaigns. A basic question that arise when designing control strategies is about which and where these ones should focus. In other words, one would like to know whether preventing the contagion or decrease vector population, and in which area of the city, is more efficient. In this work, we propose risk indexes based on the idea of secondary cases from patch to patch. Thus, they take into account human mobility and indicate which patch has more chance to be a corridor for the spread of the disease and which is more vulnerable, i.e. more likely to have cases?. They can also indicate the neighborhood where hatchery control will reduce more the number of potential cases. In order to illustrate the usefulness of these indexes, we run a set of numerical simulations in a mathematical model that takes into account the urban mobility and the differences in population density among the areas of a city. If we label by i a particular neighborhood, the transmission risk index (TRi) measures the potential secondary cases caused by a host in that neighborhood. The vector transmission risk index (VTRi) measures the potential secondary cases caused by a vector. Finally, the vulnerability risk index (VRi) measures the potential secondary cases in the neighborhood. Transmission indexes can be used to give geographical priority to some neighborhoods when applying prevention and control measures. On the other hand, the vulnerability index can be useful to implement monitoring campaigns or public health investment.

Arbovirus Vectors of Epidemiological Concern in the Americas: A Scoping Review of Entomological Studies on Zika, Dengue and Chikungunya Virus Vectors

“…Liu-Helmersson et al [107] predicted an increase in diurnal temperature range and increased dengue epidemic potential under climate changes in cold, temperate and extremely hot climates where mean temperatures are far from 29 °C. Fitzgibbon et al [193] and Velasques-Castro et al [194] studied Ae. aegypti dynamics in relation to host spatial heterogeneity.…”

“…aegypti dynamics in relation to host spatial heterogeneity. Fitzgibbon et al [193] report that early host and vector heterogeneity significantly affect final epidemic size, and Velasquez-Castro et al [194] generated a dengue infection risk map, based on host dynamics.…”

Arbovirus vectors of epidemiological concern in the Americas: A scoping review of entomological studies on Zika, dengue and chikungunya virus vectors

“…Eleven studies modelled dengue transmission dynamics [88][89][90][91][92][93][94][95][96][97][98][99]. Lee et al [95] constructed a predictive model that accurately foresaw 75% of dengue outbreaks in Colombia.…”

“…Liu-Helmersson et al [96] predicted an increase in diurnal temperature range and increased dengue epidemic potential under climate changes in cold, temperate and extremely hot climates where mean temperatures are far from 29˚C. Velasques-Castro et al [97] studied Ae. aegypti dynamics in relation to host spatial heterogeneity and generated a dengue infection risk map, based on host dynamics.…”

Next-generation high-resolution vector-borne disease risk assessment

“…However, Aedes mosquitoes have resurfaced with an even greater spatial spread, accounting for locations with more than half the world's population. Insecticide resistance has led to the need for integrated vector control measures, which are too expensive to apply on a large scale [2], [8], leading to frequent disease outbreaks as shown in Table I. Precise spatial identification of epidemic risk can enable cost-effective control.…”