Citation

Wannier SR, Worden L, Hoff NA, Amezcua E, Selo B, Sinai C, Mossoko M, Njoloko B, Okitolonda-Wemakoy E, Mbala-Kingebeni P, Ahuka-Mundeke S, Muyembe-Tamfum JJ, Richardson ET, Rutherford GW, Jones JH, Lietman TM, Rimoin AW, Porco TC, Kelly JD. Epidemics 2019; ePub(ePub): 100353.

Affiliation

Francis I. Proctor Foundation for Research in Ophthalmology, San Francisco, University of California, CA, USA; Department of Epidemiology and Biostatistics, School of Medicine, University of California, San Francisco, San Francisco, CA, USA. Electronic address: dan.kelly@ucsf.edu.

Copyright

(Copyright © 2019, Elsevier Publishing)

DOI

10.1016/j.epidem.2019.100353

PMID

31378584

Abstract

INTRODUCTION: As of April 2019, the current Ebola virus disease (EVD) outbreak in the Democratic Republic of the Congo (DRC) is occurring in a longstanding conflict zone and has become the second largest EVD outbreak in history. It is suspected that after violent events occur, EVD transmission will increase; however, empirical studies to understand the impact of violence on transmission are lacking. Here, we use spatial and temporal trends of EVD case counts to compare transmission rates between health zones that have versus have not experienced recent violent events during the outbreak.

METHODS: We collected daily EVD case counts from DRC Ministry of Health. A time-varying indicator of recent violence in each health zone was derived from events documented in the WHO situation reports. We used the Wallinga-Teunis technique to estimate the reproduction number R for each case by day per zone in the 2018-2019 outbreak. We fit an exponentially decaying curve to estimates of R overall and by health zone, for comparison to past outbreaks.

RESULTS: As of 16 April 2019, the mean overall R for the entire outbreak was 1.11. We found evidence of an increase in the estimated transmission rates in health zones with recently reported violent events versus those without (p = 0.008). The average R was estimated as between 0.61 and 0.86 in regions not affected by recent violent events, and between 1.01 and 1.07 in zones affected by violent events within the last 21 days, leading to an increase in R between 0.17 and 0.53. Within zones with recent violent events, the mean estimated quenching rate was lower than for all past outbreaks except the 2013-2016 West African outbreak.

CONCLUSION: The difference in the estimated transmission rates between zones affected by recent violent events suggests that violent events are contributing to increased transmission and the ongoing nature of this outbreak.

Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.

Language: en

Keywords

Africa; Democratic Republic of Congo; Ebola virus disease; Geospatial; Mathematical modeling; Outbreak