Geostatistical Modelling and Prediction of Rift Valley Fever Seroprevalence Among Livestock in Uganda 公开

Telford, Carson (Spring 2021)

Permanent URL: https://etd.library.emory.edu/concern/etds/rr171z49r?locale=zh
Published

Abstract

Background: Rift Valley Fever (RVF) is a mosquito-borne viral hemorrhagic fever endemic to countries throughout the African continent. Uganda is bordered by three endemic countries (Kenya, Tanzania, and South Sudan), and outbreak investigations indicate the undetected circulation of the virus among both humans and livestock. 

Methods: To determine the extent of viral circulation within the country, sampling for antibodies to RVF was carried out among herds of domesticated livestock across 28 districts in Uganda. Environmental variables were evaluated to determine their associations with RVF seroprevalence, and a final geostatistical model was fit to determine covariate and covariance parameters using model-based geostatistics. Model parameters were used to estimate RVF seroprevalence across the country for the year 2017. A map was also produced visualizing the probability that RVF seroprevalence exceeded 15% in each prediction location.

Results: Variables resulting in the best fit to sampling data of RVF seroprevalence included distance to the nearest river, distance to aquatic vegetation, standard deviation of enhanced vegetation index (EVI) over time, percent change in the standard deviation of EVI, and percent change in population density. Predicted RVF seroprevalence was highest in the Northwestern quadrant of the country, along with smaller regions in the South near the border of Rwanda and Tanzania, and in the East near the border of Kenya and North of Lake Victoria. There was high probability that RVF seroprevalence exceeded 15% in areas of high predicted seroprevalence, and low probability that RVF seroprevalence exceeded 15% in most locations in the Northeastern and Southwestern quadrants of the country.

Conclusion: Elevated RVF seroprevalence was strongly associated with proximity to water and high variability in vegetation. Variables representing change over time in population density and variation in vegetation suggest a strong correlation between increased viral circulation and anthropogenic environmental change. These results highlight specific locations in which future disease sampling and surveillance efforts should be prioritized to mitigate the risk of future RVF outbreaks.  

Table of Contents

Abstract …………………………………………………………………...………..…… 1

Introduction …………………………………………………………...………………… 2

Methods ……………………………………………………………...………………..… 5

Results ………………………………………………………………………………….. 12

Discussion ……………………………………………………………………………… 14

Conclusion ……………………………………………………………………………... 20

References …………………………………………………………………………….... 21

Figures ………………………………………………………………………………….. 27

Tables …………………………………………………………………………………... 32

About this Master's Thesis

Rights statement
  • Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.
School
Department
Subfield / Discipline
Degree
Submission
Language
  • English
Research Field
关键词
Committee Chair / Thesis Advisor
Committee Members
Partnering Agencies
最新修改

Primary PDF

Supplemental Files