Situation Report: Uganda Confirmed an Outbreak of a Rare Species of Ebola

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Uganda Declares an Ebola Outbreak

On September 20, 2022, the World Health Organization (WHO) and Ugandan health authorities declared an outbreak of Ebola virus disease (EVD), caused by the Sudan ebolavirus, in Uganda’s central Mubende district. The first confirmed patient was a 24-year-old man who presented with symptoms including high fever, diarrhea, and abdominal pain, and was vomiting blood. He later died. 

So far, seven cases, including the one death, have been confirmed. In addition, 43 contacts have been identified and 10 persons under investigation are being cared for at a hospital in Mubende.

The last reported outbreak of the Sudan ebolavirus in Uganda was in 2012. More recent outbreaks have been caused by the Zaire ebolavirus.  

Vaccines Don’t Protect Against Sudan Ebolavirus

While ring vaccination has been effective in controlling the spread of the Zaire ebolavirus in recent outbreaks in the Democratic Republic of the Congo and elsewhere, the two licensed Ebola vaccines do not offer protection against the Sudan ebolavirus. A vaccine produced by Johnson & Johnson may be effective but has yet to be specifically tested against this species (Sudan ebolavirus). However rapid case identification and early treatment of symptoms greatly increases the chances of survival and limits the spread of disease.

Learn more about the Ebola vaccine approved in the U.S. for preventing infection with the Zaire ebolavirus (CDC, https://emergency.cdc.gov/han/2022/han00477.asp, Accessed 9/22/2022).

One of Six Ebolavirus Species

The Sudan ebolavirus is one of six ebolavirus species (CDC, https://www.cdc.gov/vhf/ebola/about.html, Accessed 9/22/2022) and distinct from the Zaire ebolavirus, the species causing the recent outbreaks in the Democratic Republic of the Congo. Of the six species, four are known to cause disease in humans, and three have caused outbreaks (only one case has been documented as caused by the fourth species).

Ebolavirus Outbreaks in Africa

Zaire ebolavirus

Year	Country	Cases	Deaths	Case Fatality Rate
1976	Zaire (present day DRC)	318	280	88%
1994	Gabon	52	31	60%
1995	Zaire (present day DRC)	315	250	79%
1996	Gabon	60	45	75%
1996	Gabon	37	21	57%
2001	Republic of Congo	57	43	75%
2001	Gabon	65	53	82%
2002	Republic of Congo	143	128	90%
2003	Republic of Congo	35	29	83%
2007	DRC	264	187	71%
2008	DRC	32	15	47%
2014	DRC	66	49	74%
2014-2016	West Africa (multiple countries)	28,646	11,323	40%
2017	DRC	8	4	50%
2018-2020	DRC	54	33	61%
2018	DRC, Uganda	3,470	2,287	66%
2020	DRC	130	55	42%
2021	Guinea	23	12	52%
2021	DRC	12	6	50%
				65% (Avg.)

Sudan ebolavirus

Year	Country	Cases	Deaths	Case Fatality Rate
1976	Sudan (present day South Sudan)	284	151	53%
1979	Sudan (present day South Sudan)	34	22	65%
2000	Uganda	425	224	53%
2004	Sudan (present day South Sudan)	17	7	41%
2012	Uganda	6*	3*	50%*
2012	Uganda	11*	4*	36%*
				50% (Avg.)

Bundibugyo ebolavirus

Year	Country	Cases	Deaths	Case Fatality Rate
2007	Uganda	149	37	25%
2012	DRC	36*	13*	36%*
				30% (Avg.)

The National Emerging Special Pathogens Training and Education Center (NETEC) was stood up in the wake of the 2013-16 Ebola epidemic, which highlighted the need for rapid response and dissemination of information during an outbreak. NETEC remains prepared to support the global response to Ebola and other emerging special pathogens.