New Ebola virus disease outbreak in the Democratic Republic of the Congo: early response guidance
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)01950-6/fulltext?rss=yes
On Sept 4, 2025, in line with International Health Regulations (2005) requirements,1
the Minister of Health of the Democratic Republic of the Congo
officially declared a new Ebola virus disease outbreak in Kasai
province,2
affecting the health zone of Bulape. This new outbreak of Ebola virus
disease has occurred in a fragile context, regionally and globally, as
the Democratic Republic of the Congo is responding to an ongoing complex
humanitarian situation, as well as outbreaks of cholera, mpox, and
measles. The African region, as a whole, is adversely affected by the
current global financial and geopolitical challenges. These external
factors are likely to strain response measures in an already fragile
situation, making decisive, rapid response by all actors—regional and
international—of particular importance. Ebola
virus disease represents a major public health risk due to the
potential for international spread and high case-fatality rate, varying
between 25% and 90%.3
Experience of the Ebola virus disease outbreak of 2014–16 in west
Africa showed that, while the disease was initially assumed to occur
only in isolated areas of central Africa, spread from rural to urban
areas can occur, with substantial socioeconomic consequences.4
Both the experience of the Ebola virus disease outbreak in west Africa
and the COVID-19 pandemic show how rapidly the spread of a disease can
disrupt regional and global travel, trade, and other links.
The
Democratic Republic of the Congo has experienced 15 outbreaks of the
disease in the past five decades. The largest outbreak occurred in
August, 2018, in Nord Kivu and Ituri provinces (areas affected by armed
conflicts), with 3740 cases reported including 2287 deaths—a
case-fatality rate of 61%.
5The
fourth and fifth Ebola virus disease outbreaks in the Democratic
Republic of the Congo occurred in Mweka and Luebo in 2007 (264 cases
reported) and in 2009 (32 cases reported).
6
Kasai province is located in the south‑central part of the country, is
made up of 18 health zones, and is bordered by seven provinces (Kwilu,
Kwango, Sankuru, Tshuapa, Maindombe, Kasai Central, and Kasai Oriental)
and one country (Angola) (
appendix p 1).
On
Sept 4, 2025, the National Institute for Biomedical Research tested
three samples from patients meeting the case definition of acute
haemorrhagic fever, in
Bulape health zone (which comprises five health
areas),
Kasai province, which were found to be positive for Ebola virus (
Orthoebolavirus zairense).
7 As of Sept 14, 2025, 35 confirmed cases have been reported, including 16 deaths (case-fatality rate 45·7%).
8
Five health-care workers are among the confirmed cases.
The index case
is a 34-year-old pregnant woman who presented to the Bulape General
Reference Hospital on Aug 20, 2025, with acute haemorrhagic syndrome,
and died on Aug 25, 2025.
8
Bulape is so far the only health zone affected. The neighbouring health
zones of
Mweka, Kakenge, and Mushenge reported suspected cases, but
these all tested negative for Ebola virus.
On
Sept 2, 2025, following notification of suspected viral haemorrhagic
fever cases, the Democratic Republic of the Congo Ministry of Health and
WHO deployed the first rapid response team of experts, and shipped two
tonnes of medical supplies and a mobile diagnostic laboratory, to
Bulape
health zone and its neighbouring health zone of
Mweka in Kasai
province. The first rapid response teams reached Mweka on Sept 4, 2025,
and Bulape on Sept 5, 2025; these deployments were followed by those of
other partners such as UNICEF, Médecins sans Frontières, and The
Alliance for International Medical Action.
8On Sept 5, 2025, WHO graded the outbreak as a grade 3 public health emergency,
9
involving the WHO headquarters and Regional Office for Africa in
support to strengthen the country's outbreak response capacity. A
summary of the timeline of the outbreak, as of Sept 5, 2025, is shown in
the
appendix (p 7).
Vaccination of front-line health-care workers, contacts, and contacts of contacts started on Sept 13, 2025.
8The
current confirmed Ebola virus disease outbreak is occurring in a
province that shares borders with seven provinces and Angola. Tshikapa,
the capital city of Kasai, is accessible from the national capital,
Kinshasa, by air (two to three flights a week) and by 650 km of road.
Mweka is 278 km from Tshikapa and accessible only by road. The distance
between Mweka and Bulape is 27 km; poor road conditions make this a
journey of around 12 h. However, despite limited accessibility, there is
a high risk for the disease to spread outside Kasai province,
especially to neighbouring provinces and Angola. Preventing cross-border
spread requires urgent, rapid, and effective surveillance at points of
entry to Kasai province, as well as preparedness measures in
neighbouring areas.
Kasai
province has not experienced an Ebola virus disease outbreak for more
than 15 years. The consequent lack of experience in managing Ebola virus
disease outbreaks, coupled with a fragile health system, makes the
province poorly prepared to respond effectively to this epidemic. This
has been evidenced at the beginning of the outbreak by a shortage of
personal protective equipment for case management and safe burials, as
well as inadequate infection, prevention, and control measures.
Ring
vaccination for contacts, contacts of contacts, and front-line
health-care workers has been one of the response strategies implemented
in the last six Ebola virus disease outbreaks (in Equateur, Nord Kivu,
and Ituri provinces) and has proven effective. Fortunately, the country
had a stockpile of 2000 doses of the
Ervebo vaccine, which was
prepositioned in Kinshasa and quickly moved to Kasai.
8 It
is crucial that the Democratic Republic of the Congo Ministry of Health
and international partners rapidly control this Ebola virus disease
outbreak to prevent regional and international spread. Lessons learned
from response to previous disease outbreaks have shown that the
following are essential: (1) conduct a detailed outbreak investigation,
including retrospective active case finding back to early July, focusing
on health facilities and health areas with reported cases, as well as
contact tracing in Bulape and neighbouring health zones; (2) strengthen
infection, prevention, and control measures in all heath-care
facilities, in communities, and at points of entry in Bulape and
neighbouring health zones; (3) use experienced organisations, such as
Médecins Sans Frontières and The Alliance for International Medical
Action, for effective case management; (4) invest heavily in community
engagement to counter misinformation and prevent community resistance,
particularly against transfer of people with suspected infection to
treatment centres and against safe and dignified burials; leverage the
experience of the city of Beni during the tenth outbreak in setting up
local committees in each health area that include community leaders to
support outbreak response; (5) immediately start ring vaccination of
contacts, contacts of contacts, and front-line health-care workers; (6)
institute a data and modelling team to better inform decisions aimed at
improving the effectiveness of outbreak response, as was done during the
tenth outbreak; and (7) ensure that all response to the Ebola virus
disease outbreak strengthens affected health-care systems to
institutionalise outbreak preparedness and response measures.
This
Correspondence is intended to serve as an alert to the global
community. We must not forget the lessons learned from decades of
response to disease outbreaks and emergencies in the WHO African region,
and from the COVID-19 pandemic, namely, the importance of high-level
leadership, collaboration, and partnership.
