Epidemiologic risk of dengue and the role of human movement in an economically disadvantaged urban environment. Öffentlichkeit

Abstract

Dengue virus, the most prevalent mosquito-borne virus in the world, has been re-emerging and propagating in recent years across the world through increased host, pathogen, and vector interactions. The behavior of the host is integral to understanding dengue epidemiology and risk of exposure to the vector, Aedes aegypti. Because the vector moves relatively short distances and feeds during the day, movement patterns of humans may play an important role in disease propagation. The current study is an assessment of some of the contributions of human movement to transmission of dengue in the economically disadvantaged urban environment (EDUE) of Iquitos, Peru. Demographics of study participants as well as entomological indices at the household level were included in the analysis.

The current study drew on methods from the literature of time geography as well as novel metrics to quantify the study participants' "activity spaces." An activity space is defined by the locations visited and paths used. Activity space metrics as well as entomological and demographic variables were tested for significance in explaining rates of seroprevalence and seroincidence of dengue virus (DENV) using univariate logistic regression. Full multivariate
models for seroprevalence and seroincidence of DENV included both fixed effects (demographic, entomologic, and activity space variables) and random effects (individual participants and neighborhoods). These mixed-models were ranked using the Deviation Information Criterion (DIC) for model comparison.

The results of the study indicate that most movements are within 500 m of a house, which may be important in predicting risk and defining areas for control and surveillance. We conclude that there is no "best" model for explaining seroprevalence and seroincidence of DENV. Age of the participant and one measure of activity space, namely the sum of routinely visited locations' distance from home, were significant variables for DENV prevalence. Number of residents in house was significantly associated with dengue incidence and there were no significant variables explaining DENV-4 incidence. We discuss the limitations of the study as well as future directions and conclude that more studies are needed to explore the role of human movement in dengue propagation.

Table of Contents

Table of Contents
Introduction...1
Aims...5
Materials and methods...6

Study Area...6
Study Design...7
Data Management and Processing...10
Data Analysis...13

Results...15

Demographics and Human Movement Patterns...15
Ae. aegypti occurrence and DENV Infection Patterns...17
Determinants of Dengue Infection...18

Discussion...19
Limitations...23
Future Directions...25
References...26

Figures and Tables
Tables...29

Table 1. Summary of fixed and random effects...29
Table 2. Key demographic attributes...30
Table 3. Prevalence and Incidence by demographics...31
Table 4. Results of univariate logistic regression...32
Table 5. Summary of top 5 mixed-effects models for DENV prevalence...33
Table 6. Summary of top 5 mixed-effects models for DENV incidence...33
Table 7. Summary of top 5 mixed-effects models for DENV-4 incidence...33

Figures...34

Figure 1. Map of Iquitos, Peru and location of study areas...34
Figure 2. Illustration of spatial and non-spatial activity space metrics...35
Figures 4a) through e). Non-spatial human movement patterns...37
Figures 4f) through 4o). Spatial human movement patterns...38
Figure 5. Frequency and location types visited by neighborhood...39
Figure 7. Frequency of locations visited and distance from home...41
Figure 9. Frequency of "epi - locations" visited and distance from home...43
Figure 6. Routine locations visited by Maynas and Tupac Amaru residents...40
Figure 8. Map of routinely visited locations (RVLs)...42
Figure 10. Number of Dengue Virus Cases by Serotype and Month...44
Figure 11. Dengue Virus Isolates from Iquitos Clinics...45

About this Honors Thesis

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School	Emory College
Department	Environmental Studies
Degree	BS
Submission	Honors Thesis
Language	English
Research Field	Health Sciences, Public Health Environmental Sciences Health Sciences, Epidemiology
Stichwort	exposure human movement epidemiology dengue activity space
Committee Chair / Thesis Advisor	Kitron, Uriel, Emory University
Committee Members	Yandle, Tracy, Emory University Levy, Karen, Emory University

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