Ebola, first identified in 1976 in southern Sudan and Democratic Republic of Congo, primarily affects remote villages in Central and West Africa. Case fatality ratio (CFR) is around 50%, and ranges from 25% and 90%.

The most recent outbreak was confirmed by the Ministry of Health of Uganda on 30 January 2025 and was associated with Sudan species of the Orthoebolavirus, commonly known as the Sudan virus (SUDV). On 26 April 2025, Ugandan health authorities declared the end of the outbreak, after no new cases had been reported in the 42 days following the negative test result of the last confirmed case on 14 March 2025. The outbreak had a total of 14 reported cases (12 confirmed, two probable cases) and four reported deaths (two confirmed, two probable cases).

Pathogen(s)

Orthoebolaviruses are a single-stranded RNA virus belonging to the Filoviridae family. The genus Orthoebolavirus is divided into six species:

Zaire/Ebola virus (EBOV)
Sudan virus (SUDV)
Bundibugyo virus
Taï Forest virus
Reston virus (non-pathogenic in human)
Bombali virus (non-pathogenic in human)

It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts.

Transmission

Transmission can occur through direct contact with:

Blood, body fluids or secretions of infected persons
Tissues or body fluids of infected animals
Contaminated objects

Incubation period: Typically 5 to 15 days; range is 2 to 21 days.

Infectious period: Infected individuals are not contagious during the incubation period and become infectious once they begin to develop symptoms. They remain infectious as long as the virus is present in the blood. Ebola virus can also persist in semen of survivors and be transmitted sexually after recovery. Pregnant women who get acute Ebola and recover may still carry the virus in breastmilk, or in pregnancy related fluids and tissues.

Clinical features

Initial symptoms include:

Sudden onset of fever
Weakness
Muscle pain
Joint pain
Headache
Sore throat

This can be followed by:

Vomiting
Diarrhoea
Rash
Stomach pain
Red eyes
Impaired kidney and liver function
Internal and external bleeding

Risk factors

Risk factors include:

Unprotected exposure to blood and body fluids or secretions from infected or deceased patients (including in labs, burials or funerals), or infected animals
Direct contact with environments contaminated with a patient’s infectious body fluids

Diagnosis

Diagnosis in acute infection is primarily by detection of EBOV or SUDV by polymerase chain reaction (PCR) in blood specimens.

Diagnostic tests for EBOV or SUDV (including virus isolation) should be performed only after consultation with MOH and the National Public Health Laboratory (NPHL). Samples can be sent to NPHL for diagnosis. NPHL will provide laboratory support and guidelines for testing, including protocols for specimen transport, testing and reporting.

Treatment and management

The vaccine rVSV-ZEBOV, while approved to protect against Ebola caused by EBOV virus, does not provide cross protection against infection caused by SUDV.

The Ad26.ZEBOV/MVA-BN-Filo vaccine has only been approved by the European Medicines Agency (EMA) against EBOV and has not been tested against SUDV. This vaccine is administered on a two-dose schedule and requires 56 days between the two doses. The first dose provides protection against the EBOV and the second dose was designed to provide protection against other species of the virus, including SUDV. However, this multiantigen protection has not been demonstrated with clinical data. Studies are planned to evaluate its deployment for ring-vaccination in an outbreak setting.

For all types of Ebola, supportive care remains as the mainstay treatment. This includes diagnosis and treatment of concomitant infections such as malaria or bacterial infections in febrile returning travellers, management of fluids and electrolytes, blood product support for haemorrhage, and support for multi-organ dysfunction, including renal replacement therapy if needed.

Precaution, prevention, and control

General advice

All staff who come into direct contact with a suspected or confirmed EVD case or their body fluids, including (but not limited to) healthcare workers, persons responsible for transporting patients (e.g., ambulance staff), and cleaners should apply extra infection control measures and wear enhanced personal protective equipment (PPE) comprising of:

Disposable fluid-resistant hood to cover the head and neck areas (staff with long hair may wish to use head cover prior to wearing hood)
Eye protection gear (e.g., disposable downward face shields secured at forehead or goggles)
Fluid-repellent N95 mask
Inner and outer disposable fluid-resistant (AAMI 4) gown (should extend to below knee)
12-inch double nitrile or latex gloves certified for healthcare use (extended cuffs should reach up to mid forearm)
Disposable fluid resistant boot covers (should extend up to knee-height)

Patients who are under investigation for EVD, and pending transfer to the High-Level Isolation Unit (HILU) at the National Centre for Infectious Diseases (NCID), should be isolated in a negative pressure room minimally, and be placed on strict contact and respiratory precautions.

Only essential staff who have been pre-identified and trained in the donning and removal of PPE should attend to the patient. Staff attending to suspect Ebola cases should be closely monitored (e.g. twice daily temperature monitoring), even if they wear the appropriate PPE. Entry of non-essential staff to the patient’s room should be restricted, and a register of all staff who enter the patient’s room should be maintained and visitors should not be allowed.

Persons with skin or mucousal exposure to body fluids from a suspect Ebola case should immediately wash the affected skin surfaces with soap and water. Mucous membranes (e.g. conjunctiva) should be irrigated with copious amounts of water or eyewash solution. Exposed persons should immediately seek advice from an Infectious Diseases physician and report the exposure to MOH.

MOH will conduct contact tracing for close contacts and take appropriate follow-up actions, such as quarantine, phone surveillance, or self-monitoring. Contacts may also be referred to NCID for assessment.

Detailed infection control measures for EVD can be found in Annex A of MOH Circular 35/2019 titled “Guidance on Infection Control For Ebola Virus Disease (EVD) in Hospitals, dated 6 November 2014 (VERSION 2)”.

Notification

EVD is an emerging infectious disease and is legally notifiable in Singapore. Suspected cases will be transferred to NCID on a case-by-case basis. All confirmed EVD/SVD cases will be managed at the High-Level Isolation Unit (HLIU) in NCID.

Who should notify:

Medical Practitioners
Laboratories

When to notify:

On clinical suspicion

Suspect case definition:

Any individual with fever (>38◦C) or current history of fever AND has had exposure to a confirmed or suspect case of EVD, or the body fluids (i.e. blood, urine, faeces, tissues, laboratory cultures) within the past 21 days.

On laboratory confirmation of positive PCR or virus isolation

How to notify:

Please refer to the Infectious Disease Notification for more information.

Notification timeline:

Immediately

Resources

Get EVD situation updates from the World Health Organization (WHO).

Get Sudan Virus Disease situation updates from the WHO.