Effect of a safe and dignified burial intervention on Ebola virus transmission in the eastern Democratic Republic of the Congo, 2018-19: a propensity score analysis.

Abstract

Safe and dignified burial (SDB) is a pillar of the response to epidemics of Ebola virus disease and other diseases caused by pathogens transmissible through contact with corpses. A large epidemic of Ebola virus disease affected eastern DR Congo during 2018-20, throughout which the DR Congo Red Cross and local authorities, with support from the International Federation of Red Cross and Red Crescent Societies, provided SDB services. We aimed to estimate the effect of SDB performance on the transmission of Ebola virus during this epidemic. For this quasi-experimental propensity score analysis, we retrospectively approximated intervention randomisation conditions by grouping geographical-time observations on the basis of their similarity in terms of potential confounder variables representing epidemiological surveillance, vaccination coverage, insecurity, and infrastructure. We computed two transmission outcomes by health zone and week: the change in Ebola virus disease incidence over adjacent 2-week time windows and the effective reproduction number. We modelled the association between the proportions of timely (same-day) and successful (involving a secured body, environmental disinfection, and safe burial) SDBs (as exposures) and either transmission outcome while adjusting for potential confounding by combining variables identified through a directed acyclic graph into propensity scores that help to group observations, in order to approach randomised trial conditions. SDB timeliness and successfulness were associated with respective reductions of 7% (95% CI -6 to 18) and 40% (22 to 54) in incidence across adjacent time windows, and with decreases in the log reproduction number (linear coefficient -0·39 [95% CI -0·81 to 0·03] and -0·45 [-0·74 to -0·16]). A dose-response relationship with SDB successfulness was apparent for both transmission outcomes. Transmission decreased below the epidemic extinction thresholds when more than around 40% of SDBs were successful. The SDB service was associated with a substantial and plausibly causal reduction in the transmission of Ebola virus during the 2018-19 epidemic in eastern DR Congo. This intervention should be considered whenever exposure to corpses contributes to epidemic propagation. Elrha's Research for Health in Humanitarian Crises Programme. For the French translation of the abstract see Supplementary Materials section.