DISEASE AND OUTBREAK CHARACTERISTICS
1. Ebola virus is a single-stranded RNA virus belonging to the Filoviridae family. The genus Ebolavirus is divided into six species (Zaire, Sudan, Taï Forest, Bundibugyo, Reston and Bombali). The Zaire, Sudan, Taï Forest and Bundibugyo species cause human disease, whereas Reston and Bombali viruses are non-pathogenic in human.
2. Following a change in the nomenclature and classification by the International Classification of Diseases (ICD-11) for filoviruses in May 2019, Ebola disease is now sub-categorised depending on the causative virus. Outbreaks of Ebola disease caused by Sudan virus (SUDV) are also known as Sudan Virus Disease (SVD) outbreak.
3. SUDV was first identified in southern Sudan in 1976 and has since been responsible for seven outbreaks (four in Uganda and three in Sudan). SVD (or Ebola disease caused by SUDV) is a severe, often fatal illness affecting humans with a Case Fatality Ratio (CFR) between 41-100% in past outbreaks. At present, there are no licensed vaccines or therapeutics for the prevention and treatment of SVD.
4. The current Ebola disease outbreak in Uganda was declared on 20 September 2022 and is associated with SUDV, according to genomic sequencing confirmation of the index case.
5. In the event of an importation, prompt recognition of suspected cases and infection control practices in healthcare institutions will mitigate the risks and prevent onward transmission.
6. Animal-to-human transmission may have occurred from close contact with contaminated tissues and bodily fluids of infected animals (ill or dead rainforest animals such as fruit bats, chimpanzees, gorillas, monkeys, forest antelope or porcupines). Human-to-human transmission can occur through direct contact with blood, other bodily fluids or secretions from an infected person, including corpses or through direct contact with environments that have been contaminated with an SVD patient’s bodily fluids.
7. The incubation period ranges from 2 to 21 days. People infected with SUDV cannot spread the disease until they develop symptoms, and they remain infectious as long as their blood contains the virus.
8. Symptoms of SVD are similar to the Ebola Virus Disease and can include sudden onset of fever, fatigue, muscle pain, headaches, sore throat, followed by vomiting, diarrhoea, rash, impaired kidney, liver functions and even internal and external bleeding.
9. The diagnosis of SVD can be difficult, as early non-specific manifestation of the disease may mimic other infectious diseases. As the signs and symptoms for SVD are varied and non-specific, doctors should be alert to any traveller from SVD-affected regions with a febrile illness and should always ask for a travel history.
10. SVD should be suspected in an individual with:
- Fever (>38°C) or current history of fever
- Onset of symptoms within 21 days of
i. travel history to an area with reported SVD activity or outbreak (currently in Uganda), OR
ii. has had exposure to a confirmed or suspect case of SVD.
11. All suspect cases of SVD should be notified to the Ministry of Health (MOH) immediately via the Surveillance Duty Officer. MOH will provide further instructions on the management of the cases, including transfer of suspected cases to the National Centre for Infectious Diseases (NCID) on a case-by-case basis. All confirmed cases will be managed at the High-Level Isolation Unit (HLIU) in NCID.
12. Diagnosis in acute infection is primarily by detection of SUDV by PCR in blood specimens. Diagnostic tests for SUDV should be performed only after discussion with MOH and the National Public Health Laboratory (NPHL) and 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.
13. There are no licensed vaccines or therapeutics for the prevention and treatment of SVD. The vaccine rVSV-ZEBOV (ERVEBO®), while approved to protect against the Zaire strain of Ebola, does not provide cross protection against SUDV infection.
14. The Johnson & Johnson (Janssen) vaccine, Zabdeno/Mvabea, has only been approved by the European Medicines Agency (EMA) against Zaire Ebola virus disease 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 Zaire ebolavirus and the second dose was designed to provide protection against other species of the virus, including Sudan. However, this multiantigen protection has not been demonstrated with clinical data. Even if the vaccine was tested and proved to be effective against SUDV, it would only provide protection some days after the second dose is administered. Studies are planned to evaluate its deployment for ring-vaccination in an outbreak setting.
15. In the absence of proven antivirals, supportive care remains the mainstay of treatment for SVD. 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.
16. Patients who are under investigation for SVD, and pending transfer to the HLIU in 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 case. Entry of non-essential staff to the patient’s room should be restricted, a register of all staff who enter the patient’s room should be maintained and visitors should not be allowed.
17. All staff who come into direct contact with a suspect or confirmed SVD 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)1 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); and
- Disposable fluid resistant boot covers (should extend up to knee-height).
18. As a precautionary measure, staff in contact with the case or their body fluids should be closely monitored (e.g. twice daily temperature monitoring), even if they wear the appropriate PPE.
19. Waste generated from suspect patients should be double bagged, sealed and disposed of by a licensed waste-contractor. Application of disinfectants should be preceded by cleaning. Disinfectants should not be sprayed. Cleaning should always be carried out from “clean” areas to “dirty” areas, in order to avoid contaminant transfer. In general, environment surfaces should be cleaned and disinfected using 5,000 ppm sodium hypochlorite. However, when the surface is contaminated with blood, other body fluids, secretions or excretions spill, 10,000 ppm sodium hypochlorite is to be used.
20. Contacts of persons with SVD or healthcare workers with unprotected exposure to an infected patient or their body fluids are at risk of acquiring disease. Such exposures include exposure of mucous membranes or broken skin to blood/body fluids (including respiratory secretions), without the proper PPE, or needle stick injury.
21. In the case of exposure to an infected person, exposed persons should immediately seek advice from an Infectious Diseases physician and report the exposure to MOH. Close contacts will be contact traced by MOH and appropriately followed up (e.g., quarantine, phone surveillance or self-monitoring). Contacts may also be referred to NCID for assessment.
22. Detailed infection control measures for SVD 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)”.
1 Enhanced PPE is designated for those with direct patient care/contact. Many hospital staff will thus not need to follow the enhanced PPE recommendation. In such cases, hospitals’ own protocol should be followed.