Epidemiology of Sudan Ebolavirus Disease Cases in Uganda, January-April, 2025.
Abstract
Background
On January 30, 2025, the Ministry of Health, Uganda (MoH), announced an outbreak of Sudan ebolavirus disease (SVD). We describe the epidemiological characteristics and transmission dynamics of the SVD outbreak in Uganda during January-April, 2025.
Methods
SVD cases were identified using MoH case definitions and were classified as confirmed if positive on RT-qPCR or probable if an SVD-related death was reported with epidemiological linkage but without laboratory confirmation. Cases were identified through contact tracing, community and health facility alerts, and active search. Data were collected using a standard SVD case investigation form, including demographics, exposures and outcome. The effective reproductive number (Rt) was estimated using the EpiEstim package in R.
Results
Fourteen cases were identified between January 30 and April 25, 2025: 12 (86%) were confirmed and 2 (14%) were probable; and 5 (36%) were health workers. The mean (range) age was 27 (0-50) years. Four cases died, a case fatality rate (CFR) of 29% (4/14). Most exposures were household (9[64%]) followed by healthcare-associated exposures (3[21%]). The index case was a health worker who died of a febrile illness 11 days after symptom onset, and postmortem samples returned positive for SUDV on the same day. A total of 534 contacts were monitored; of these, 454 (85%) were quarantined. Ten cases were known contacts; no secondary transmission occurred among these cases. The estimated Rt (interquartile range) was 1.1 (0.83-1.35).
Conclusion
The outbreak had a low CFR and a low Rt, possibly due to early detection and swift identification, quarantine, and close monitoring of contacts.